TRANSPORTATION MARKINGS:  A  STUDY IN COMMUNICATION
MONOGRAPH SERIES
VOLUME I  FIRST STUDIES IN TRANSPORTATION MARKINGS: 
PARTS A-D, First Edition (Foundations, A First Study  in
Transportation Markings: The U.S., International
Transportation Markings: Floating Fixed Marine]
University Press of America,  1981
Second Impression, Mount Angel Abbey,  1993
PART A, FOUNDATIONS
Second Edition, Revised Enlarged,
Mount Angel Abbey  1991
PART B, A FIRST STUDY IN TRANSPORTATION MARKINGS: THE U.S.
Second Edition, Revised Enlarged,
Mount Angel Abbey 1992
PARTS C D, INTERNATIONAL MARINE AIDS TO NAVIGATION
Second Edition, Revised,
Mount Angel Abbey,  1988
VOLUME II  FURTHER STUDIES IN TRANSPORTATION MARKINGS: 
PART E, INTERNATIONAL TRAFFIC CONTROL DEVICES,
First Edition,
Mount Angel Abbey, 1984
PART F, INTERNATIONAL RAILWAY SIGNALS,
First Edition,
Mount Angel Abbey,  1991
PART G, INTERNATIONAL AERONAUTICAL AIDS TO NAVIGATION,
First Edition,
Mount Angel Abbey, 1994
PART H, A COMPREHENSIVE CLASSIFICATION OF TRANSPORTATION MARKINGS
Projected
VOLUME III  DATA BASE OF TRANSPORTATION MARKING PHENOMENA: 
PART I, "Rolodex" Format PART  J, Computer Format
Projected
TRANSPORTATION MARKINGS: A STUDY IN
COMMUNICATION MONOGRAPH SERIES
VOLUME II FURTHER STUDIES IN
TRANSPORTATION MARKINGS
PART G
INTERNATIONAL AERONAUTICAL NAVIGATION AIDS
Brian Clearman
Mount Angel Abbey
1994
Dedicated to the Memory of
LDC, 1928-1992
Copyright (c) 1994 by Mount Angel Abbey
at Saint Benedict, Oregon 97373
All Rights Reserved
Library of Congress Cataloging-in-Publication Data
Ciearman, Brian.
International aeronautical navigation aids / Brian Clearsan.
p. cm. -- (Transportation markings . v. 2) (Further studies
in transportation markings : pt.  GI
Includes bibliographical references (p. 1 and indexes.
ISBN 0-918941-08-3
1. Airports--Traffic control--Display systems. 2. Traffic signs
and signals. 3. Aids to air navigation. I. Title. II. Series.
Clearaan, Brian. Transportation markings , v. 2. III. Series.
CIearman, Brian. Further studies in transportation markings :  pt.
G.
TAl245.C56 1984 vol. 2. pt. G
(TL725.3.547]
629042 s--dc20
(629.121 94-14557
CIP
Note: the LC # preassigned to this monograph is different
than the one printed in the CIP data sheet. The preassigned
S is 94-076173
TABLE OF CONTENTS
Preface vii
Acknowledgments viii
Abbreviations .
33 AERONAUTICAL NAVIGATION AIDS: INTRODUCTION 
EARLY DEVELOPMENTS
A Introduction
1 Terminology, The Nature of
Aero Transportation Markings 
Methodological Concerns . 1
2 Aeronautical Nov Aids: Physical
Properties Semiotics . 9
34
B History of Aero Nav Aids
1 Introduction Early Aviation
Developments .
2 Early History of Aero Aids,
1919-1937.
3 Development of Aero Aids,
1938-1943.
4 Final Developments Before ICAO,
1944-1950.
THE CLASSIFICATION
A Main Classification
1 Introduction
2 Main Classification.
3 Explanatory Notes .
B Variant Classification
1 Classification.
2 Explanatory Notes .
C Pictorial Representations
1 Illustrations .
2 Explanatory Notes
16
20
32
37
49
51
54
60
63
72
78
iii
35 LIGHTED AERO NAVIGATION AIDS
A Approach Lighting
1 85
2 Equipment. 87
3 Messages . 89
B Final Approach Lighting
1 92
2 Messages . 93
3 Equipment. 99
36
C Runway Taxiway Lighting
1 Background, Terminology 
Functions.
2 Inset Lights .
3 Elevated Lights
4 Messages for Inset  Elevated
Lights .
D Beacons Obstruction Lighting
1
2 Beacons .
3 Obstruction Lights .  
4 Messages for Beacons Obstruction
Lights . 
PARTIALLY-LIGHTED UNLIGHTED AERO
NAVIGATION AIDS
A, Signs Markings
1 Introduction to Chapter 36 .
2 Signs: Types Messages . 
3 Markings: Types Messages .
B Indicators, Markers, Obstruction
Markings Restricted Use Markings
1 Indicators: Types Messages .
2 Markers: Types Mesages.
3 Obstruction Markings: Types 
Messages .
4 Restricted Use  Area Visual
Aids
101
102
105
107
112
113
115
118
121
123
124
129
130
134
136
iv
37 AERO ELECTRONIC NAVIGATION AIDS
A Fully Integrated Systems
1 Chapter 37: Overview 
Changes . 139
2 Instrument Land  ing Systems 142
3 Microwave Landing Systems . 145
B Independent Partially Integrated
Aids
1 VOR, TACAN, VORTAC DME.  148
2 Beacons Multi-mode Radio
Aids. 151
APPENDIX: COMPARATIVE REVIEW OF ICAO AERO
NAV AIDS, 1949-1991. 159
BIBLIOGRAPHY . 169
INDICES:
i General Index . 191
ii Index of Types of Aids
and Systems 193
iii Index of Names: Personal,
Corporate Organizational 207
V
C
N -
PREFACE
Volume II of the TRANSPORTATION MARKINGS: A
STUDY IN COMMUNICATION MONOGRAPH SERIES
continues the studies began in Volume I, Parts
A-D. The earlier volume reviewed communication
concepts - especially those of semiotics and of
the role in transportation markings (Part A) -
and it presented a survey of surface, air, and
marine markings in the U.S. (Part B). The first
volume ended with an examination of one segment
of international transportation markings: marine
aids to navigation ( Parts C D). Parts C D
were revised and republished as a separate unit
in 1988 under the title of International Marine
Aids to Navigation.  A major revision of Part A,
Foundations, has also been completed. The
revision includes an enlargment and revamping of
semiotic considerations, an addition of material
on electromagentic and acoustical processes with
their role in transportation markings, and an
addition of material on design and trans-
portation markings. Part B has also undergone
revision including a major expansion of the
classifications.
Volume II continues the international
studies begun with Parts C D. There are four
intended parts for the second volume:
International Traffic Control Devices  (Part E),
published in 1984; International Railway Signals
(Part F) published in 1991; Aero- nautical
Navigation Aids  (Part G), the focus of the
present study; and A Comprehensive
Classification of International Transportation
Markings  (Part H), projected.
The present monograph examines currently
employed radio and visual aero aids.
vii
Officially-sanctioned aids - as presented in
International Civil Aviation Organization (ICAO)
and augmented by North Atlantic Treaty
Organization (NATO), U.S. and other sources -
provides much of the foundation of the study.
This format is true of the other monographs in
the Series as well. Classification continues
its vital role for the studies. A subchapter on
aero history is also vital to the monograph.
The monograph views radio aids and visual
aids as a single, unified subject. That may
run counter to the many who view radio aids as
navigation aids,  and visual aids as airport/
airfield/visual/ground aids. Few, in fact,
speak of a single field of aero safety devices
no matter what terminology is employed. The
problem of a split is mirrored in the lack of an
agreed upon overarching term. The use of "aero
navigation aids" by the writer may lead to
confusion and to irritation by those seeing two
disciplines or one discipline with two
semiautonomous aspects. Yet some unified
designation was necessary if one perceives a
single field.
ACKNOWLEDGEMENTS
To Abbot Peter Eberle and the Monks of Mount
Angel
To those who assisted in the production of the
monograph: Mark Parker OSB, proofreading; Justin
Hertz OSB, computer assistance; Pius Harding and
his staff at the print shop, covers and
supplies.
viii
To many libraries that rendered aid: Air
University Library in Alabama; the University of
California, Davis Libraries; the University of
California, Berkeley Libraries especially
Catherine Cortelyou and her colleagues at the
Institute of Transportation Studies Library;
Congress; Humboldt County Library, especially
Lena, the inter-library loan person in Eureka
and Joy Moore in McKinleyville; International
Civil Aviation Association Library, Montreal;
Mount Angel Abbey Library, especially Darlene
Strand, inter-library loan coordinator; Oregon
State University Library; Portland State
University Libraries; University of Oregon
Libraries; University of Washington Libraries.
To many manufacturing concerns that supplied
information: Airflo Instruments, Glastonbury CN;
Thorn Europhane, Paris; Cegelec, Paris;
Crouse-Hinds, Windsor Locks CT; EG, Salem, MA;
Hughey Philips, Sind Valley, CA; TWR, Houston,
TX; Ameriel, Atlanta; Siemens, Braunsweig,
Germany; Godfrey Engineering, Tampa, FL; ITT
Avionics, Nutley, NJ; Jacquith Industries,
Syracuse, NY; Mannairco, Mansfield, OH; Nautel,
Tantallon, NS, Canada; Slo-Idman Oy, Mantsala,
Finland; Omnipol/Tesla, Praha; Ulmer
Aeronautique, Paris; ADB, Zaventem, Belgium;
Unitron International, Atlanta; Danaid,
Copenhagen; Toshiba, Tokyo; Valley Illuminators,
Tukwila, WA; Westinghouse Electric, Cleveland;
General Electric, Hendersonville, NC; Sepco,
Windsor Locks, CT; Sylvania, Electric Products,
Ipswich, MA; Tull Aviation, Armonk, NY;
Multi-Electric, Chicago; Devore, Alburquerque;
Wilcox, Kansas City, MO.
To many governmental aviation organizations that
rendered assistance: Civil Aviation Authority,
ix
Canberra, Australia; Regie der Luchtwegen,
Zaventem, Belgium; Transport Canada, Ottawa,
Canada; Civil  Aviation Administration,
Copenhagen, Denmark; Aviation Civile, Paris,
France; Deutsche Flugscherung, Offenbach,
Germany; Aeronautica Civil,  Mexico; NATO,
Brussels; Luftfartsverket, Oslo, Norway; Civil
Aviation Authority, Singapore; Aviacian Civil,
Madrid, Spain; Civil Aviation Administration,
Norkopping, Sweden; Federal Office of Civil
Aviation, Bern, Switzerland; Civil  Aviation
Administration, Taipei, Taiwan; National Air
Transport Services, United Kingdom; Federal
Aviation Administration, Department of
Transportation, and Department of Defense, U.S.
To individuals and organizations that helped in
various ways: European Organisation for the
Safety of Air Navigation (Eurocontrol),
Brussels; Senator Mark Hatfield; David Page 
History of Air Navigation Group, London;
National Archives, Seattle Washington, D.C.;
B.A.J. Clark and the Aeronautical Research Labs,
Melbourne.
ABBREVIATIONS
Journals 
AIM Airman Information Manual
AIP Aeronautical Information Publication
(published by many nations)
AI Airports International
AW Aviation Week
LD Literary Digest
SA Scientific  American
SNL Science  News Letter
Organizations 
AACI Airports Internationale d
Eclairage/International
Commission on Illumination
CAA Civil Aviation Authority or
Administration (various nations
use either term)
CAB Civil Aeronautics Board, U.S.
CIE Commission Internationale
DOT Dept of Transportation, US. also
USDOT
DOD Dept of Defense, U.S.
FAA Federal Aviation Administration, U.S.
ICAO International Civil Aviation
Organization, Montreal
IES Iluminating Engineering Society
IHB International Hydrographic Bureau
MOD Ministry of Defense, U.K.
NATO North Atlantic Treaty Organization
PICAO Provisional ICAO
Technical Terms: Radio Aids 
ADF Automatic Distance Finding
AM Amplitude Modulation
BCM Back Course Marker
DME Distance Measuring Equipment
DVOR Doppler VOR
FM Frequency Modulation
GHz Gigahertz
GPS Global Positioning System
Hz Hertz
ILS Instrument Landing System
IM Inner Marker
KHz Kilohertz
LF Low Frequency
MF Medium Frequency
xi
MHz Megahertz
MLS Microwave Landing System
MM Middle Marker
NDB Nondirectional Beacon
OM Outer Marker
SBA Stanard Beam Approach
TVOR Terminal VOR
UHF Ultra High Frequency
VHF Very High Frequency
VOR VHF Omndirectional Range
VORTAC VOR TACAN
Technical Terms: Visual Aids 
AAI Angle of Approach Indicator
AOE Alignment of Elements
ALSF Approach Lighting with Sequenced
Flashers
APAPI Abbreviated PAPI
AT-VASI Abbreviated T-VASI
AVASI Abbreviated VASI
CD Capicitator Discharge
CHAPI (nothing: CH or Cegelec)
DBGA Double Bar Ground Aid
FLOLS Fresnel Lens Optical Landing System
GAIL Glide Angle Indicator Lights
GPI Glide Path Indicator
GVGI Generic Visual Glideslope Indicator
GVDI Generic Visual Descent Indicator
HAPI Helicopter Approach Precision Indicator
MALSR Medium Approach Lighting with RAIL
MDLA Mirror Deck Landing Aid
PAPI Precision Approach Path Indicator
PAR Parabolic Aluminized Reflector
PCOLA Pulse Coded Optical Landing Aid
PLASI Pulse Landing Approach Slope Indicator
PVG Precision Visual Glideslope
POMOLA Poor Man Optical Landing Aid
xi i
RAIL Runway Alignment Indicator Lights
REIL Runway End Indicator Lights
RILS Runway Indicator Lights
RTIL Runway Threshold Indicator Lights
RT-VASI Reduced T-VASI
SAVASI Simplified Abbreviated VASI
SSALR Simplified Short Approach Lights with
RAIL
SSALSF Simplified Short Approach Lights with
Sequenced Flashers
TDZ Touchdown Zone
TLLAS Two-light Landing Approach System
T-PASI Tactical Portable Approach Slope
Indicator
T-VASI Tee-VASI
TVG T-Visual Glide Slope
VAPI Visual Approach Path Indicator
VASI Visual Approach Slope Indicator
VGPI Visual Glide Path Indicator
General Terms
ATC Air Traffic Control
IFR Instrument Flight Rules
NPR Nonprecision Instrument Rules
PIR Precision Instrument Rules
VFR Visual Flight Rules
TISRP This Is Source for Remainder of
Paragraph(s)
CHAPTER THIRTY-THREE
AERONAUTICAL NAVIGATION AIDS:
INTRODUCTION EARLY DEVELOPMENT
33A Introduction
33A1 Terminology, The Nature of Aeronautical
Transportation Markings 
Methodological Considerations
A basic term for the totality of
aeronautical transportation markings proves to
be a problem though a smaller one than for
railway transportation markings which lacks any
over-arching term. By contrast, marine and road
transportation markings each have such a term:
marine aids to navigation for the former, and
traffic control devices for the latter.
It may be possible to employ aids to
navigation since many aero aids bear some
resemblence to marine aids and because both
share some electronic aids. Admittedly, that
use of the term would be an atypical use of it
and would undoubtedly create confusion. A 1947
tome entitled Radar Aids to Navigation  did,
however, clearly include both marine and aero
navigation aids (ed. by Hall; see especially
essay by Buck, Ch 2). The most likely term
would be navigation aids since that can
encompass both radio and visual portions. AIM -
in older editions - employs that term though
seemingly no other publication employs it (FAA
1973, Table of Contents). ICAO employs "visual
aids for navigation" and "radio navigation aids"
(ICAO Annex 10 1985 TC; Annex 14 1990, TC).
1
U.S. AIP uses "aerodrome lighting and marking"
and "navigational aids" and "radio navigation
aids" (FAA AIP 1991, TC). Manufacturers use
various terms including airport lighting
(Crouse-Hinds 1992); aviation lighting (ADB
1991); airport ground lighting equipment
(Cegelec 1992); and airfield lighting (Idman
ud). To be sure, those terms encompass only
visual aids.
This compiler employed visual and radio
navigation aids in a letter to the
standardization agency of NATO but they were
unable to understand my reference. NATO prefers
to speak of airfield lighting and marking
(Wilson 1993). Navigational aids has a
different meaning for NATO.  A  U. S. Navy essay
also employs the term airfield lighting (Naval
Facilities 1981). RAE also employs airfield
lighting (RAE Smith 1988). Field in his
International Air Traffic Control speaks of
navigational aids having two definitions:
"ground-based" aids and "airborne" aids (Field
1985, 26). Airborne equipment is employed to
make use of ground aids. A third meaning refers
to airborne equipment that takes in data from
sattelites and natural bodies. Field appears to
accept my definition as well as that of NATO.
Navigation aids seems appropriate for this study
and is, in fact, the only adequate term for the
entire scope of aero transportation markings.
Business Week  (11-11-44, 76) speaks of "air
navigational aids" presumably for all forms but
that is clearly a dated source.
The special nature (or special features of
the nature) of aeronautical navigation aids
includes several features: 1) all other modes of
transportation have nineteenth century
2
antecedents; 2) many of the elements of the
color code and accompanying meanings were in
place before aero aids; 3) the technology of
signal glass and quality control of glass
manufacture had been established by the advent
of aero aids; 4) and many elements of
transportation equipment were substantially
developed. It can also be noted that while
conventional airplanes are a primary focus of
the study other forms of aviation including
helicopters, STOL and V/STOL craft are not
excluded.
In addition, an international character was
established early for aviation. This was
brought about by propensity of aviation to
transcend national boundaries, by the need for
trans-nation safety aids, and by the involvment
of a few nations in pioneer aviation development
whose work quickly spilled over the bounds of
those states.
The international character and the place of
a single agency looms up larger for aviation
aids than for any of the other three transport
modes. A fully-developed and relatively modern
system of navigation aids did not occur until
after ICAO came into existence; though, to be
sure, substantial work on many of the
foundations was underway. This is not a case
where international efforts came after a long
span of development and in which historical and
factors of national inertia precluded a well-
thought out international stance. ICAO monitors
national divergencies through periodic
supplements to the aerodrome agreement.
Differences, however, are relatively limited and
a general agreement on aids exists (see
Supplements to Annexes 10, 14).
3
By comparison, traffic control devices did
not reach substantial convergence until the 1968
UN conference (UN 1969). National and regional
customs, over more than fifty years, reduced
that convergence and a residue of divergence
produces a lingering tension. A somewhat
similar situation is found in marine aids to
navigation though that divergence, within a
recently crafted convergence, is more notable.
The national focus of railway signals has
substantially blocked a meaningful international
system; admittedly, an international dimension
to railway safety aids is less essential than it
is for aero aids.
An aura of the western nations permeates
aeronautical navigation aids and a substantial
part of that aura is from the U.S. This may
appear to be a regretable and unfortunate
chauvinism. If a world of diverse and numerous
nation-states had existed in and around 1900
then a different cast to international
transportation markings would presumably exist.
But the fact of many colonies and subordinated
nations, the possession of much of the advanced
technology, communication and transportation
systems by a few nations brought about safety
aids influenced and shaped by a few nations in
the West. Even though many aero aids are
relatively new, the long-enduring dominance of
aviation by the US and a few European states
laid the foundations for a system of aids that
continues to be greatly influenced by those same
few nations.
Previous remarks on ICAO indicate the place
of ICAO, as well as its publications, in the
methodology of this study. Among the plethora
of ICAO publications three are primary for this
4
study: Aeronautical Telecommunications  (Annex
10),  Aerodromes  (Annex 14), and Aerodrome
Design Manual  (Part 4, Visual Aids). Current
editions are of greatest importance though past
editions have been consulted especially for
historical matters. The methodology, though
substantially based on ICAO, also includes works
of NATO and the U.S. FAA. Selected national
publications also have a role as do a variety of
manufacturing publications.
The methodology is a relatively simple one:
a classification has been constructed using the
aforementioned publications. This classi-
fication forms the basis of the study out of
which descriptions of the types of markings and
their messages is formulated. Historical
vignettes of aero aids constitutes an outgrowth
of the classification and the descriptive
treatments.
The lack of a central source of data for the
railway signal study required basing that study
on the individual systems and which, in turn,
required determining which systems were
significant in size as well as those that were
diminutive. Statistics, therefore, occupied a
key position in that study. The core statistic
for that study consisted of rail lines mileage/
kilometers. While admittedly an imperfect tool
for determining signal usage it did afford a
means to know which railway systems were more
likely to have substantial signal systems and
those less likely. Statistics play a less
central role for aero aids. Yet knowing the
nations that handle large numbers of passengers,
cargo and mail - even knowing the length of air
routes - can provide an indicator of nations
heavily involved in aero aids. The figures  will
5
indicate that a small number of nations dominate
the various categories of aviation and
statistical compilations. Air route distances
was once a common statistic in aviation but that
statistic has become much less common as it does
not indicate if substantial usage of given
routes has taken place.
Sources of statistics include the ICAO
annual report, UN Statistical Yearbook
(1989/1990),  Europa Year Book  (1986), The World
in Figures  (1988) , International  Marketing Data
and Statistics  (1993), European Marketing Data 
Statistics  (1993), and New Book of World
Rankings  (1991). The most important source is
that of ICAO with augmentation from other
sources  (ICAO Journal 1990 1992).
It is possible to present a plethora of
figures detailing not only numbers of
passengers, amounts of cargo and mail, distances
traveled as well as more sophisticated
indicators that combine passenger, cargo, and
distance travel into passenger miles and
kilometers and cargo miles and kilometers. That
level of detail is not warranted here. In fact
a calculation that combines passengers, cargo,
and mail and distance will be the primary
indicator employed here: tonne-kilometers This
figure, not found in many sources (but it is
employed by ICAO and also by the UN), considers
total weight of an aircraft (including the
passengersbaggage ) and distance traveled. A
tonne-km (or mile-km) is the weight of one ton
carried one mile (CAB 1977; also ICAO Lexicon).
It is the first indicator presented by ICAO. A
second indicator, the number of airports, is
given by World Book of Rankings and that too
seems important in gaining an idea of numbers of
6
aero aids and their diversity and
sophistication.
There are approximately 190 nation-states at
the present time. These include some
micro-states as well as fledging nations wracked
by the carnage of conflict that may never
achieve an independent existence. ICAO includes
164 in its membership rolls (ICAO Journal Annual
Report TISRP). The 1992 figures speak of the
Russian Federation which seemingly includes the
former Soviet Union; the full range of new
nations are not included. Quite possibly Russia
alone generates most of the aviation activity.
ICAO gives details on 90 of the 164. The 90
nations are responsible for over 99% of the
tonne-km total. 31 nations have at least one
million tonne-km; this constitutes some 93% of
the total tonne-km and those nations have
received more attention in this study.
Five nations have nearly two-thirds of the
tonne-kms: the U.S. (36.2%), Russian Federation
(9.9%), Japan and U.K. (each 9.9%), Germany
(3.7% ) and France (3.6%). A second group have
11% of tonne-km: Australia and Singapore (2.3%
each), Canada and The Netherlands (2.2% each)
and South Korea (2%). The first two groups have
slightly over 75% of global tonne-km.
Two other groups totalling 20 nations
contribute 17% of the tonne-kms. Brazil, Italy,
China, Spain, Switzerland, Thailand and
Scandinavia (Denmark, Norway and Swedish have a
joint airline: Scandinavian Air Service or SAS)
have 1.0 to 1.6% each of the total. Malayasia,
Saudi Arabia, India, Indonesia, Mexico, Israel,
New Zealand, Philippines, Gulf States (Bahrain,
Oman, Qatar, United Arab Emirates), Pakistan,
7
Belgium, South Africa and Argentina have .5 to
1.0% each of the total. One final entry may be
noted: Air Afrique, though a smaller operation,
represents ten west-central and west African
states (Benin, Burkina Faso, Central African
Republic, Chad, Congo, Ivory Coast, Mauritania,
Niger, Senegal and Togo) known as the Yaounde
Treaty States.
The New Book of World Rankings provides
statistics on airports with scheduled services.
The first ten nations have just over half of the
world airports with scheduled services. The
U.S. has 21% of the total and Australia has 11%.
Papua New Guinea has some 4.5% though it does
not rank high in other statistics. Brazil,
India and Indonesia have from slightly less to
slightly over 2.5% each of the total. Colombia
and China have 2% each and Mexico and France
1.8% each. Other nations with more than 25
airports include Japan and Argentina (1.7%
each); Canada (1.6%); USSR (1.3%) and The
Philippines (1.1%). Norway, U.K. and Venezuela
have 1.0% each. Italy, New Zealand, South
Africa, Sweden, Madagascar, Malayasia, French
Polynesia, Ethiopia, Germany, Greece and Spain
hae .7 to .9% each of the total. 70% of the
nations included in the earlier statistics are
also represented here. Papua New Guinea,
Madagascar and French Polynesia are not included
in the early statistics but Ethiopia is so
listed and ranks 53rd. Colombia at 32 and
Venezuela at 34 are very close to ranking on
both lists. For that reason Columbia and
Venezuela are added to the major aviation
nations for this study but not Papua New Guinea,
Madagascar or French Polynesia.
8
ICAO has received an uneven response to
queries about compliance/non-compliance with its
standards for aero aids. This can be seen in
the Supplements where only a minority of member-
nations respond. The attempt to gain
information from nations active in aviation has
had a similar fate. Slightly under 50% of those
nations responded to requests for data. More
positively, some 80% of the very active nations
(the first ten) responded. The information
received ranged from miniscule to massive.
The statistical study has proven to be of
value though often in ways not directly germane
to the original intent of the survey. It has
helped to confirm the markedly high level of
consensus in international aero aids. It has
also highlighted the terminology conundrum:
requests for visual and radio aid data
frequently resulted in radio information only.
This supports the view  expressed earlier that
for many persons in aviation the term navigation
aids means only radio aids even if one sought
visual aids material as well. One correspondent
even assigned visual and radio aids to the field
of avionics which can be far removed from both
visual and radio aids.
33A2 Aeronautical Navigation Aids: Physical
Properties Semiotics
There are several basic tools that can be
employed to study transportation markings:
1) Semiotics studies messages and their meanings
and that proves fruitful for the entire
Monograph Series. 2) Communication theory goes
beyond semiotics by including the physical
dimension of the communication process. See
9
Foundations  (Part A, 2nd ed) in this Series for
further information).
3) "Semiotics of the Object": Roland Barthes
(Barthes 1988, 180-184) crafted what he termed
the "Semiotics of the Object" which focussed on
objects not considered to be semiotical in
intent. That approach is important for
transportation markings not only because it can
encompass all dimensions of transportation
markings but also because Barthe saw the
semiotic of the object within a framework of the
symbolic and of taxonomy. Both elements are
vital to transportation markings.
4) Technology and Physical Properties.
While the studies are not technological
treatises they do include technology and
especially the descriptive treatment of physical
properties. Physical properties treats of the
technology as it creates and frames the means
through which messages are composed and emitted.
It goes beyond the concerns of physical
processes in communication theory and also goes
beyond Barthe semiotics of the object.
In this monograph only a terse treatment of
these several topics can be employed. Those
topics will center on semiotics - and especially
aspects most vital to markings, and on physical
properties (but without a formal review of
communication theory, the semiotics of the
object or technology). The topic of
classification is taken up in Chapter 34.
This introduction to semiotics and physical
properties may be overly long for the
accompanying treatment. The length is prompted
by a review of introductory materials in Part F.
10
That review revealed that while all these topics
are included they lacked the necessary
coordinating linkage. These present comments
are intended to be a contribution to the entire
Monograph Series. Chapter 1 of  Foundations
takes up these matters in more detail. The
Prolegomena of that study may also be consulted.
Semiotics can be briefly defined as the
study of signs in whatever form. Only one phase
of semiotics, that of semiosis or sign process
needs to be discussed here.  Foundations offers
a longer review of semiotics as well as
providing information on sources. Two
dimensions of semiosis, sign and signification,
are of particular importance here.
Sign, in a semiotic sense, can be viewed as
the visual aspect that a transportation marking
(or other semiotic sign) displays. In some
transportation markings, such as unlighted
signs, the semiotic sign and the physical
dimension of the marking are virtually fused
together into one unit while in other markings
the message and physical properties can be more
readily separated. Signification can be
regarded as the meaning that a message conveys;
for example, a fixed green light signifies, or
has the meaning of, "proceed" in traffic
signals; green has more atypical meanings with
aero threshold or taxiway centerline uses.
It may be noted that semiotic professionals
may prefer physical sign, form or designator in
place of sign, and they may further prefer
message/meaning or designatum in place of
signification (Givon 1990).
11
It proved to be a relatively simple task to
describe railway signals in semiotic terms. For
example, the term "aspect" in railway jargon
equalled sign, and the term "indication" denoted
signification. Railway signals with its
changing colors and other symbols and
accompanying messages fitted well with semiotic
concepts. (see also  International Railway
Signals,  Part F).
Aero navigation aids can be viewed in a
semiotics framework but it is more complex and
less easily grasped since, paradoxically, its
simpler caste is elusive and less immediately
displays the dimension of meaning. Instead of a
single unit displaying a color (the sign) with
its meaning (signification) one is confronted
with (in many instances) rank upon rank of fixed
lights emitting a steady burning and never
changing message. Instead of a unit saying,
"caution" or "proceed" or "halt" one is presnted
with  a row of single color and unblinking
lights. For example,  a pattern of blue lights
for a taxiway consists of dozens of lamps and
they never do anything other than display that
fixed blue indication. What do they signify?
They denote the bounds of the taxiway lane which
are the spatial limits of safe navigation after
a plane arrives.
Marine aids to navigation employs many
channel markers; which, though somewhat similar
in function to aero aids, bear marked
differences. Each marine aid has an identity in
itself, each aid identifies a location as well
as forming a segment of a pattern of markings,
and each can be more precisely defined
semiotically than aero counterparts. Aero aids
therefore display a semiotic notion but in a
12
different configuration than many other
transportation markings. Interrelationships are
more important and individuality is less so.
This is less true of obstruction and some
approach aids but it is true of most other aero
navigation aids.
The physical properties of aeronautical
navigation aids include the specific medium they
adopt, the actual configuration of the aid, and
the nature of the message that the aid is
capable of producing and displaying. The
technology of the aid is included though more in
a descriptive manner than in an explicitly
technological fashion in this study.
Mediums refer to how the aid produces and
emits the message. The basic mediums are the
visual, the electronic, and the acoustical.
Both the visual and electronic have major roles
for aero aids. Electronic impulses take on a
visual and/or acoustical form in the aircraft-
borne receiver. Acoustical is not found with
aero aids otherwise (though there is a curious
acoustical signal that appeared briefly in the
1930s; see page 28). The visual medium contains
all-lighted, partially-lighted, and unlighted
variants.
The fully-lighted variant is relatively
small since only approach and related lights are
in use around the clock. Partially-lighted has
a somewhat different meaning for aero than it
does for marine. Partially-lighted for marine
indicates an aid with explicitly day and night
dimensions. But with aero aids it refers to a
light-only aid that functions only at night and
in limited visibility. Pavement markings, a
separate aid, often furnish the day dimension.
13
Signs are a point of confusion since they often
have a lighted dimension, though not always,
which places them within both unlighted and
partially-lighted categories.
Partially-lighted signs adds an additional
variant meaning to that phrase. Unlighted aids
are largely in the form of markers and markings;
obstruction aids are also included in that
category. There is a marked degree of
uniformity in the mediums. Unlike railway
signals a given form of aid varies little from
airport to airport or from manufacturer. The
physical differences in manufacture are quite
limited since standards are precise in their
requirements. What differences there are
pertain to intensity (high, medium, low) and to
direction (unidirectional, bidirectional and
omnidirectional).
There is a narrow and uncertain line between
the physical properties of aero aids and the
semiotics of aero aids. Signs and markings
closely integrate the physical and symbolic but
for many lighted aids it is possible to
distinguish between physical and semiotic.
However, the nature of the message capability of
a transportation marking partakes of both
dimensions. The nature of the message that an
aid can produce ties together the physical and
semiotic meanings of aero aids. Since the
nature of the message is tied more closely to
the physical that topic is attached to physical
properties aspect of the coverage.
The nature of the message concept is first
found in Volume I, Part A, 1st edition. It is
reproduced here to provide both context and
linkage for aero aids. It is reproduced here to
14
provide a context for aeronautical messages.
Many aero aids messages are similar to those of
marine aids: a message that is single and
unvarying. This is in contrast to many rail and
road signals which provide a variety of
messages. But the message configurations are
more complex than those two examples. The basic
construct of message capability natures has this
pattern:
1. Multiple capability that permits Changing
Message/Multiple Message (C3M);
2. Message capability that permits only
Changing Message/Single Message (CMSM);
3. Message capability that includes an
Unchanging Message but with Multiple Messages
(U3M);
4. Message capability that is restricted to
Unchanging Message and Single Message (UMSM).
The fourth form (UMSM) includes the
following sub-categories:
I. Programmable Transportation Markings.
II. Unitary Markings include several variants:
A. Single and unchanging message;
B. Intermediate which permits one of
several predictable versions;
C. Individual which includes markings for
whom few, if any, predictions can be made.
Most, perhaps nearly all, aeronautical
navigation aids are UMSM. Most of these are
within the II.A. sub-category. Some signs and
pavement markings are within II.B. and a limited
number may be within II.C. Stop and Clearance
Bars are in all likelihood part of the first
category, Changing Message/Multiple Message
(C3M).
15
33B History of Aero Navigation Aids
33B1 Introduction Early Aviation Developments
This study focusses on current aeronautical
aids. It is not a history of aviation or even
of aero aids. However, aviation seems to be a
virgin field in many respects; written materials
that exist for marine, road and rail may not
exist for aero studies. For example, a variety
of historical studies exist for traffic control
devices (Sessions 1970 and Mueller 1970 among
others have written extensively on that topic).
Yet comparable studies are not available for
aeronautical stuidies.
In the 1970s I attempted to find information
on taxiway lights. My sources included primary
ones such as Charles Douglas, formerly of the
National Bureau of Standards, who was involved
in aero lighting in its earlier period. Other
materials included people still living and
technical information. Elimination of Douglas,
other living resources and hard-to-find
materials would have had the end result of
little available information on taxiway lights.
More recently David Page (History of Air Navi-
gation Group of The Royal Institute of Navi-
gation, U.K.) has indicated that while they are
studying the history of navigation (and radio
aids to a degree) they have not studied visual
aids and have few clues to that history (Page
1993). Remarkably, even though that group is in
close proximity to the subject of aero aids they
have encountered little information on it.
Therefore this subchapter will endeavor to
offer a sketch of some seminal events in
aviation history and of the development of aero
16
aids. A half-chapter cannot be definitive but
at least an outline of the subject can be given.
This may suggest to a reader that a general
history of aero aids is very much needed.
Chapter 33B will consider three themes:
aviation developments and aero aids to 1937
(33B2), a segment which stops at a seemingly
arbitrary point but a point that actually
encompasses a plausible period of development;
aero aids 1938-1943 (3383), a short selection
that includes numerous significant events;
1944-1950, a period that includes the early
years of PICAO/ICAO and vibrant with aero aids
developments (33B4). 33B4 also includs
international cooperation before 1944, and an
epilogue on approach lighting after 1950 because
so many foundational developments fall outside
the time frame of this segment.
The airplane became a reality in 1903 in
North Carolina. Even though some time was to
pass before the airplane could be seen as a
practical machine, it was not that many more
years before the airplane became relatively
commonplace with both passenger and mail
services available (Gibbs-Smith 1985, 94).
Passenger services began in Italy during
World War I and several other passenger
operations were established in Europe before
World War I ended (Warner, 1938, 34-35).
Regular passenger service did not begin in the
U.S. until 1927 (Taneja 1987, 2).
Several flights transversed the Atlantic in
1919 including a non-stop flight; this marks the
expansion of flight beyond continental bounds
(Gibbs-Smith 1985, 181). The 1920s is very much
17
and the airway spanned the continent before 1926
ended. Great aerial lighthouses were
established in Europe but they were few in
number and any form of systematic lighted route
was unheard of. However, Europe was well ahead
of the U.S. in radio aids and established
frequent radio units providing direction finding
capabilities for aero navigation.
Before 1939 nearly all of the world had been
reached by aeronautical transportation. Between
1931 and 1935 the British Empire and Common-
wealth had been stitched together by air:
Central Africa in 1931, South Africa in 1935,
East Asia in 1933, Australia in 1935.  Air
service between Belgium and the Congo were
established in 1935. And French Indo-Chinese
air service began in  1938.  Pacific aviation was
established in 1935 and 1936 from the U.S. The
rugged terrain of South America proved to be an
impetus for developing aviation and a variety of
carriers offered service either to restricted or
continental areas of the continent.
Areas that were developed relatively late
included Canada and the North Atlantic.
Aviation was certainly present in Canada but
trans-continental service did not begin until
1938 (Davies 1989, 169; Finch 1938, 21; see also
Follett). But the thinness of the population,
proximity of most residents to the U.S. and its
aviation system, and extensive rail networks
mitigated against early continental
developments. The North Atlantic was the last
principal region to experience regular air
service. Distance and state of aircraft
development precluded early development of that
route. It was only on the eve of World War II
that regular passenger service was begun. And
it ended within a few weeks not to recommence
until after the war.
18
a pioneer era for aeronautics yet both
experimental flights and even regularly
scheduled services began in that time. KLM
began service to what was then termed the Dutch
East Indies in 1924 (Finch 1938, 159). Air
France reached South America in 1927 and 1928
through a multi-phase process via Natal in west
Africa. Aptly named Imperial Airways (U.K.)
reached India in 1929 (Finch 1938, 19). An
experimental flight from California landed in
Australia in 1928 (Finch 1938, 199-200).
But these flights were not at night.
Imperial Airways, for example, took nearly a
week to reach India in the earliest period of
flight and the route was flown in segments and
only in daylight hours (Harper 1930, 141).
Night flying took place in Europe but only in
the summer and in northern latitudes where
darkness was very limited in that season. some
experimental nights flights also took place
(Warner 1937, 27). Saint Exupery describes
night mail flights in South America made without
navigation aids but it is not clear how
extensive that practice proved to be (Saint
Exupery 1942).
Night flying as a regular event took place
only in the U.S. during the 1920s and that was
exceptional even in the 1930s. Warner views the
lighted airway system of the U.S. as the
greatest contribution to aeronautical operations
by the U.S. (Warner 1937, 26-29 TISRP). The
U.S. Army established the world first lighted
airway (with regular, scheduled flights) in 1921
in Ohio. The Post Office took over that route
and expanded it from Chicago to Cheyenne in 1923
and regular  air mail service began in the
following year. New York was included in 1925
19
33B2 Early Development of Visual Aids
Aero lighting of the 1920s and 1930s was
markedly simple. The controlling image of that
early phase of lighting for many people may
center on early airway beacons whether a great
aerial lighthouse in Europe or the vast system
of beacons strung across American prairie and
mountain. However, many of the lights were far
more prosaic and oft times they were boundary
lights.
The boundary light, as the name implies,
outlined the total landing area of an airport.
It did not delineate approach channels, runways
or taxiways (Wood 1940, 311; Duke 1927, 122).
Despite what it "did not delineate" the boundary
light is the probable precursor of many
contemporary forms of lights including
threshold, runway and taxiway.  LD spoke of
"border lights" in 1926 and these were
presumably the same form of light (Lighting the
Night Mail, 7-31-26, 18).
Standardization of messages did not reach
contemporary levels but some general statements
can be made. U.S. forms were white in color
(though in 1929 the Dept. of Commerce provided
for either white or yellow lights; Aids to
Better ... . 1929, 127) while red remained in
considerable use for many other nations (Black
1929, 160). But exceptions exist: St John
Sprigg speaks of amber (a saturated form of
yellow) and Finch notes the use of international
orange (St John Sprigg 1934, 109; Finch 1938,
20
28). Lights could be either fixed or flashing
though fixed was more common (Black 1929, 160).
Even at an early date it was recognized that
some approaches to an airfield were superior to
others and this recognition led to use of green
lights, known as range lights, within the line
of boundary lights for recommended approaches
(Black 1929, 16). One source (The Lighting of
Airports, 1928, 104-105) speaks of these lights
as approach lights. However they bear little
resemblance to approach lighting. What they do
resemble are threshold lights. Later on green
not only designated the best approach but the
importance of a given runway at an airport. The
importance of a runway was denoted by the number
of green lights (2, 3 or 4) (Wood 1940,
311-312).
The spacing of boundary lights varied from
200 to 300 feet. 300 feet became the maximum
permitted spacing in the U.S. (Black 1929, 160;
Duke 1927, 122; Wood 1940, 311; Whitnah 1966,
35). Some boundary lights were equipped with
red globes. These lights denoted hazards near
the landing area and supplemented standard
obstruction lights. Contemporary lights
infrequently have a day dimension but that was
not the case at an earlier time. Boundary
lights were equipped with a cone-shaped object
of sheet metal and painted to denote a message
corresponding to the night message. Two yellow
bands intersected by a single black band denote
a regular boundary light. Range lights
displayed vertical chrome yellow and white
stripes (Aids to Better ... . 1929, 127).
Presumably boundary lights were fixed though
one journal article described a flashing
boundary light. Quite possibly that never went
21
beyond an experimental stage (Flasher Lights .
. 1934, 38).
The impression that specific colors have
certain meanings has long persisted. For
example, yellow means caution, green denotes
proceed, red indicates danger. But only the
color red has long had the message associated
with it (the color termed ruby may well be
within the red spectrum. Some older sources use
the term but not more recent ones. An article
in AC mentions ruby for obstruction lights;
Lighting in . 1928, 104). This is very much
exemplified by obstruction lights: they are red
in all nations and at all times. White strobe
lights represents a recent exception; an
obstruction light at Chicago was also white
(Oea 1958, 105). Possible confusion over
colors and meanings that may be found with
boundary lights and even with beacons is absent
with obstructions lights.
Early obstruction lights were to be found in
both fixed and flashing forms. Many were
incandescent though some neon forms were
employed (if CAA reference to a gaseous form
indicates neon; CAA 1941, 16-21). Boundary
light sometimes included mention of obstruction
lights. One 1929 source describes that form of
obstruction light in detail and further notes
that the cone was painted in red and white
vertical stripes (Aids to Better ... . 1929,
127). There are numerous references to
obstruction lighting; two older sources are
Harper 1930, 128 and St. John Sprigg 1934, 109.
Lb refers to "red guard-lights but  presumably
the same form of light was meant (Lighting the
Night Mail, 1926, 18).
22
Beacons are the most visible element in
early aviation developments. Light sources for
beacons included incandescent, acetylene,
electric arc and neon forms. Incandescent and
acetylene were the most common forms in use.
Few beacon lights were of a fixed character;
most either rotated or flashed. In most
instances larger beacons were of the rotating
form (Black 1929, 152; Lighting in . 1928,
105; see also numerous journal articles and
treaties on early aviation). LD notes a great
beacon that pointed skyward and so rotated that
an enormous circle was created that could be
seen 50 miles (Night Mail, 1923, 17).
U.S. Airway beacons were of two types
(Komons 1978, 135-136 TISRP). The first and
older one displayed a single-direction 24" lamp.
The lamp rotated a white message. The tower was
constructed on a concrete slab in an arrow shape
with a black edged yellow pattern. There were
course lights as well on the tower. One faced
toward the next tower while the other faced
toward the previous tower. Two successive
towers displayed red lights; the third tower
displayed a green light denoting an intermediate
landing field. The course lights flashed
according to a Morse code characteristic
denoting a number from one to nine. The numbers
represented the position of the tower in a
one-hundred mile segment of the airway.
A new light was introduced in 1931 Komons
1978, 135-136; see also Airway Beacons, SA,
12-32, 323). This was a double-ended lamp with
clear and colored flashes; these were either red
or green according to the position of the beacon
on the airway. Course lights were no longer
needed. This beacon was a standard for U.S.
23
aero lighting; the lamp revolved six times per
minute (FAA 1980). The code beacon was
introduced in the early 1930s (Breckenridge
1955, 9; sources are abundant for many topics
but  the code beacon has been seemingly
overlooked and source materials are limited).
This beacon performed a variety of functions and
continues in use to the present day. It served
not only as a code beacon (displaying Morse code
characteristics) but also as an auxiliary beacon
and hazard beacon. Its role as a hazard beacon
is the present primary function of that beacon.
A variety of auxiliary beacons were employed
as well. These included a routing beacon which
was similar to marine lanterns (The Night Mail
in Reality 1923, 16-17). This beacon was placed
at regular intervals between the main beacons.
But it was seemingly employed for only a few
years. A range lantern was also employed in
hard to reach localities (Komons 1978, 137).
The range beacon had a second purpose as well.
In rugged terrain, where a beacon might not be
seen at any distance, the range lantern was
employed between the main beacons.
Komons (1978, 134-135) notes that the
essential notion of aerial lighting originated
with marine aids to navigation; this fact
influenced the placement of the Airways Division
in the Lighthouse Bureau. But marine and aero
navigation do not represent identical situations
and U.S. airway lighting diverged from marine
practices. But in Europe aerial lighting
closely imitated that of marine lighting.
Europeans created literal aerial lighthouses of
massive power. Intermediate landing fields were
absent as well as evenly spaced airway beacons.
24
The European approach is exemplified by the
Dijon aerial lighthouse built in 1923 (The
Aerial Lighthouse 1923, 400 TISRPS). This
single light marked the Paris-Algiers aero
route. The Dijon light was 10 meters/33 feet
high. It contained two groups of lenses which
faced opposite directions. Each group of arc
lamps produced a one billion candlepower beam
which constitutes an incredibly powerful light.
But instead of a well-marked path from Paris to
Algiers the aviator had this single, vast optic
for guidance.
A somewhat smaller beacon was produced by
AGA. This was presumably of less power and
seemingly a manufactured beacon in contrast to
the the Dijon light. But it too was also an
aerial lighthouse and one that bore a striking
resemblance to marine lighthouses. The AGA
beacon comprized a revolving lamp and lens
within a glass lantern house. However, it did
not have the precise focus of the U.S. beacons.
Goldstrom notes that there are three forms
of beacons: aerodrome, "flashing beacons near
large centers" and the long-distance forms
(Dijon and Valerian). There is seemingly few
other references to the flashing beacons that
Goldstrom mentions (Goldstrom 1930, 144).
Aerodrome beacons in Europe and Australia,
were often of a neon form (see Parnell 
Boughton  1988, 153,  on Australian developments).
Some observers were of the view that red neon
lights were especially fog-piercing (Caldwell
1930, 316-317;  other sources for this topic
include Black 1929, 162-163; Harper 1930, 127).
Others claimed instead that any form of red was
fog piercing. A third view suggested that neon
25
red was more effective because of longer wave
length. white can be seen further than any
color and it is not clear how red, neon or
otherwise, was superior to white in fog.
Norvell notes that red and yellow are better in
fog not because of their longer wave length but
because fog creates more of a halo effect around
shorter wave lengths of, for example, blue and
green, which in turn creates glare near the
light source (Norvell 1940, 116). Westinghouse
produced a sodium light in 1939 that pierced fog
more effectively as compared to incandescent
light. It is not clear whether it was the form
of light or the fact that the sodium lights were
amber (saturated yellow) tht constituted the
improved visibility (Sodium Lights ... . 1939
(Sept): 158.
Wind indicators, both wind cones and wind
tees, were an early feature of aviation. The
characteristic shapes of wind indicators is
virtually unchanged over 60 or more years.
Oea notes that presence of an unspecified form
of wind indicator at Hounslow in 1920 (Oea
1958, 105). Wind cones were in use in 1929 and
probably for some years before (Black 1929,
116). Wind cones were often lighted; the
lighting providing a substitute for daylight
rather than as a message in itself.
Wind tees are more frequently mentioned in
the literature. They were equipped with green
lamps outlining the "T" shape which is the
contemporary practice as well (Duke 1927,
122-123). Lighting for wind tees, in contrast
to wind cones, is part of the message. Wind
tees may have lost their official status, at
least in the U.S., but they continue to be
manufactured and employed and the shape and
26
lighting are unvaried from that earlier period.
See Lighting of Airports 1928 on this topic.
The full panopoly of aero signs and markings
did not exist at an earlier day. Signage and
pavement markings (lines, words, numbers) were
substantially absent. Nonetheless, there were
markings in great abundance of some types.
There was a great concern to paint the names of
towns on roofs during the 1920s as is attested
by the literature (see for example, Air Markers
1923, 58; Young 1928, 127-192; Making the Air
Safe for Everybody 1923, 58; Airmarking for
Cities 1927, 307; Airmarkers, Time,  1936, 48).
Distance and directional arrows sometimes
accompanied the name of the town. Lighting,
either by floodlighting or by creating words
with individual lamps, was sometimes employed.
Names of towns were painted at airports as well.
Letters were frequently in chrome-yellow on a
black background (Young 1928, 127).
Circle markers were to be found both in
North America and in Europe. These markers, as
much as a 100 feet in diameter, marked the
location of airports. Smaller circle markers
sometimes denoted runways (Greif 1979, 12-13).
White seems to be the predominant color for the
various markings. The day dimension (which
could appropriately employ the marine term,
daymark) of boundary lights is considered in the
treatment of boundary lights. And the material
on airway beacons includes mention of
accompanying directional arrows. Harvey notes
the use of "homemade boundary markers in the
early post World War I era and these were also
in white; lights were added to some of these
markers at a later time (Harvey 1941, 84).
27
Visual aids, though prominent, did not make
up all the navigation aids before World War II.
Aero radio aids were introduced early in the
century and soon manifested several forms.
Radio aids included approach aids, non-
directional beacons, guidance aids and rotating
beacons.
Floodlights are not included in this study
since they are more akin to sunlight than to
aids to navigation. The status of ceiling
lights is less clear. These lights illuminated
the cloud cover and its heights. They are
possibly a form of navigation aid (The Lighting
of ... . 1928, 106).
Probably the most unusual aero aid was the
"sonic marker beacon". It might be seen as the
aviation equivalent of a marine acoustical or
fog signal. Its role was similar to radio
marker beacons. In theory the pilot would hear
the first beacon when past the 500 foot point
before the boundary of the airport. After
entering a middle area the pilot would hear a
second sonic beacon. It was developed by
General Electric and underwent tests in 1933.
Little evidence of this unusual aid is in the
literature (Sonic Marker Beacon 1923, 32). The
vagaries of acoustical signals would seem to
quickly eliminate such an aid for aero purposes.
An early form of the rotating beacon was
produced by the Telefunken Company in 1907.
This beacon contained 32 aerials (one for each
point of the compass) grouped around a central
aerial. A complete transmission began with a
starting message from the central aerial with
each of the other aerials transmitting in turn.
Position was determined by measuring the
28
transmissions, beginning with the central
signal, and continuing until the signals reached
the zenith of power; the most powerful signal
indicated the aircraft position. The
Telefunken beacon is regarded as the predecessor
of all rotating beacons since it was ground
based rather than airborne thereby permitting
unlimited use of the beacon, and because the
quality of transmissions was unaffected by
airborne equipment (Kendal 1990, 315). The U.S.
began work on a rotating beacon in 1936. This
and other work resulted eventually in the VOR or
VHF Omni Range aid (Kendal  1990, 320-321).
The Course Setter of Otto Scheller (Lorenz
Company) produced a means of determining an
aircraft course with one radio unit; this too
was in 1907 (Kendall 1990, 321). The unit two
aerials each transmitting a letter: "A" by one
and "N" by the other. If "on the beam" the
aircraft received a steady hum of the merger of
the two letters. But if off course then "A" or
"N" was received. Further tests were conducted
but aircraft aerial problems terminated the
development of the course setter. However, it
serves as a forerunner of other guidance aids.
Early radio beacons developed by Marconi
developed a "wireless lighthouse" or radiobeacon
in 1916. They were primarily marine in focus
though some aero use of the radio beacon
occurred (Kendall 1990, 318).
The U.S. Post Office experimented with radio
navigation aids in 1919 and 1920. They created
a directive beacon employing a spark transmitter
over the Chicago-New York route. The experiment
was short lived but the U.S. Army continued work
on radio navigation and eventually played a role
29
in the development of the radio range (Komons
1978, 153-154).
The Radio Range is based on the work of
Scheller. The Scheller form transmitted
interlocking signals from aerials producing
. figure-of-eight patterns. This created  four
ranges or tracks. The patent for this aid was
filed in 1916. In 1924 the U.S. produced the
radio range based on the earlier work. It was a
MF unit and became standard U.S. radio aid until
VOR in the 1950s (Kendal 1990, 319). Grover,
however, lists it as  a LF/MF frequency aid
(Grover 1957 41). Much of the practical
development and application was during the years
1928-1931. The transmission was a Morse code
one of A (._) and N (Kayton 1990, 229; see
also Komons 1978, 155-161; Hall 1947, 44-45).
The Radio Range provided information on
direction along the range but not the actual
position of the aircraft. Marker beacons were
added that provided that information. The
transmissions were fan-shaped along the track
and cone-shaped at the the station itself
(Grover 1957, 41). The messages were received
in the aircraft in both lighted and aural forms
(Kayton 1990, 229).
A fuller development of the Course Setter
known as the Standard Beam (SBA) created an
airfield approach system. SBA was widely
employed in U.K. until ILS superseded it. The
unit provided azimuth and location information
through the employment of marker beacons thereby
assisting aircraft in their landing approach
(Kendal 1990, 321).
30
Bellini-Tosci in 1907 created an early
version of the ground based direction finder
(DF). A fuller development resulted in a major
system of aids that was the standard aid for
European navigation until VOR. During World War
I both U.K. and Germany established stations
along their respective coasts; stations were
also established at airports. The system had
shortcomings for nighttime use and a different
aerial system known as the Adcock was
substituted (Kendal 1990, 324-325).
Early work on ILS began in the 1920s and
1930s in the U.S. Work began in 1919 and one
system had been tested by 1929. VHF range was
found to be the best frequency in 1931. The
three current elements of glide path, localizer
and marker beacons were determined early in ILS
development. Conflicting ideas slowed
development of ILS until the early 1940s (Wilson
1979, 127-128).
31
33B3 Development of Aero Navigation Aids,
1938-43
The complexity of runway and taxiway lights
and accompanying lights of current airports
contrasts sharply with airport lighting in the
1920s and much of the 1930s. There was a single
form of lighting for most airports in that era:
boundary lights. The range lights that were in
use constituted an integral component of
boundary lights.
Gradually other forms of lighting were
added: these included runway edge and threshold
lights. Lights not only included cone shaped
boundary type lights but semiflush lights, and
lights on pedestals. There were high intensity
lights as well as low intensity forms. Lights
known as strip lights joined boundary and runway
lights.
Airport lighting developments become
confusing since boundary lights did not vanish
to be replaced by other forms. Boundary lights
continued in use while other forms were added
on. During a transitional period the various
forms overlapped with one another and perhaps
were not far from contradicting one another on
occasion.
Despite the multiple forms of lights in use
during that time, it may not be far fetched to
suggest that boundary lights are the basis of
many airport lighting forms. Boundary lights
began as a macro state outlining the entire
landing area and evolved to micro forms
delineating a precisely formed runway. Range
lights evolved into threshold lights. And in
situations where red lights existed (Australia
32
for one) in the line of boundary lights they
became runway end lights. Runway lighting
standards in about 1940 consisted of contact
lights spaced 200apart with 1000of yellow
lights from the threshold point followed by
3000of white lights (Norvell 1940, 116).
There is, however, no simple evolutionary
process. Old forms and new forms became
intermingled. Yet boundary lights can be seen
as the antecedent, as an evolving core to the
developments that followed.
Taxiway lighting is a relatively recent
development. Early airports were simple affairs
with boundary lights and, frequently,
floodlights. Runway lighting was generally
absent and taxiway lighting was fully absent.
Douglas of NBS states that taxiway lights did
not exist before September of 1938 but they were
in use by 1941 or 1942. An 1946 U.S. publi-
cation from the Army-Navy-Civil Committee
established what may be the first standard for
taxiway lights (Army-Navy-Civil Committee 1946;
also Navy 1946).
Taxiway lights were blue in color. Taxiway
edge lights were initially semi-flush in
character though some elevated models for snow
areas were in use. Reflector delineators were
also provided (Navy 1946, 10-11).
The original approach lights consisted of
neon lights in a short row installed to the left
of the runway. The neon lights were of greater
intensity than other airport lights and this
greater brightness led to a proposal to use them
day and night. Up to that time airports lights
were in use only at night. Tests at Nantucket
33
and at Indianapolis found that approach lights
were of value during foggy periods during the
day. Two rows of lights were preferred to the
current single row. A form of light known as.
the Bartow light was employed during World War
II in Alaska and had two rows of lights. But
the lights were weaker than the test patterns
and were of limited value. It is not known
precisely when approach lights were employed and
there is a double problem of experimental work
and official status. The exact beginnings of
approach lighting has not been located by this
writer. Wood makes mention of this form of
lighting in 1940. Breckinridge speaks of
approach light early in the 1935-1945 decade.
References for approach lighting include CAA
Pushes ... . 1950,  47; Kroger 1948, 21-22; CAA
1941, 16; Breckinridge 1955, 15-16; Airport
Lighting System 1939, 375; Wood 1940, 312;
Glidden 1946, 194.
Final approach glideslope indicators
development occurred largely outside this time.
However, one form was developed by Royal Air
Force (which later developed PAPI). This early
indicator which was a optical projector ground
aid was a three-color system displaying green to
a pilot on the glideslope, a red warning if too
low and an amber message if too high. Most
later indicators are two color systems but some
three-color types are in use (Clark Antonenko
1993, 51;  Clark Gordon 1981, 1) .
Runway lights, as distinct from boundary
lights, began between 1936 and 1939
(Breckinridge 1955, 13, 15-16; Wood 1940, 312).
These lights known as contact lights of the
marker type ( so named since "they do not
attempt to light the surface of the runway.
34
Instead they direct their light toward the
incoming pilot ... ." (Norvell 1940, 44) were
originally of a semi-flush design. Quite early
in their development they displayed two colors:
amber or yellow for the lights at the beginning
of the runway, the first 1000 feet, and white
beyond that point. Threshold lights, presumably
a descendent of boundary range lights, were
green. Red lights for runway ends were employed
at an eary date in Australia; red was also
employed for wrong-direction warnings already in
1939 (Parnell 1988, 153).
Beacons continued on in a similar pattern to
the earlier period. Some newer forms were added
for smaller airports and cold-weather usage but
they did not essentially alter the existing
forms. Breckinridge speaks of the wind-tee as
coming into use during this time period but
older sources clearly indicate its use in the
1920s (Breckinridge 1955, 14).
Radio aids did not vary greatly from the
earlier period. Radio ranges, marker beacons,
and direction finding units continued in use.
Work toward what became VHF Omni Range (VOR) was
well underway however. In the U.S. experiments
with VHF began in 1937 and an actual change from
MF to VHF commenced in 1940 but war requirements
ended the project. The old radio range was a
four-course arrangement and early VHF was a
two-course system. But research developed a
omni-range VHF system in 1943. But it was not
until the early 1950s that VOR became a reality.
Principal reference for this coverage is Kendal
1990.
During 1939 and 1940 various ILS systems
were tested. A system developed by
35
International Telephone Development Company
(ITD) eventually was selected. A great deal of
wrangling between civil and military aviation
interests slowed the project and the start of
World War II largely ended the project during
the war. A few civil airports and some military
airports did have the system during the war
(Wilson 1979, 127-129; also Kayton 1990, 237;
and Kendal 1990).
36
33B4 Final Development of Aero Aids Before ICAO
Standards, 1944-1950
Approach lighting has undergone only limited
change for the last quarter century and much
longer for some key concepts. This is true for
lights, messages and equipment. This is
remarkable both in regards to other aids and to
the turbulent history of approach lights. Many
airport have undergone design and technological
changes over four decades, and some new aids
have been added but approach lighting has been
largely unscathed.
Two qualifying statements need to be made
regarding approach lighting and its coverage in
this segment. Even though general agreement was
reached early in the 1950s on approach lighting
it was not until the late 1960s that the U.S.
government approved and implemented what been
substantially agreed upon long before. Pre-ICAO
aero aids coverage ends in about 1950 since by
then ample standards have been prepared and
implemented. But approach lighting was somewhat
slower in development and because of the
tardiness of the most active aviation nation,
the U.S. For that reason an epilogue has been
added to this segment on more recent events in
approach lighting.
The United Kingdom developed its approach
lighting system in the 1940s and that system is
sustantially the same today. By contrast the
U.S. has experienced multiple and contradictory
developments in its first years of development.
Even a cursory sketch of that development
borders on the incredible. This treatment is
37
disproportionately centered on the U.S. because
so much of the turmoil took place there.
The source materials for approach lights
part of this segment overlap and interweave with
one another; therefore the sources are grouped
together here: Kroger, 1948, 18-25; New  Lighted
. 1948, 374; Wilson 1979, 236-241; Lights
for Landing 1958, 58. And a long series of
articles in Aviation Week:  Approach Lights
5-8-50, 46-47; Lights Squabble 5-2-49, 14; New
Policy 11-20-50, 55; Slopeline Light ....
12-6-48, 15; ALPA-Recommended . 3-7-49, 40;
CAA Pushes 6-19-50, 47-49; Moore, 12-11-50,
46-52; CAA Tests ... . 7-49, 43.
Indianapolis was the site of many  early
(1945) experiments including Bartow lights,
centerline lights, and "angled approach"
systems. Arcata was perhaps more notable  with
the passge of time. In 1948 the U.S. was close
to approving the Slopeline Approach Light
system. That system consisted of two rows of
lights having the shape of a funnel with the
narrow end near the runway threshold. The light
units making up the rows were at a 45 degree
angle and each consisted of 10 sealed beam
lamps. When a pilot was on course the two rows
of lights displayed two lineal strips of light.
But when off course the lights took on the
appearance of a slanting picket fence. Height
and position of the plane could be determined by
the direction and slant of the light units. In
1948, as approval seemed near at hand, the CAA
was both preparing specifications and bids for
the slopeline system and preparing for further
tests for a centerline approach system that
airline pilots preferred to the slopeline.
38
In 1949 ALPA  strongly criticized the CAA's
testing program at the Arcata Airport
(McKinleyville, CA). A key criticism concerned
the much  greater intensity of slopeline lights
in the test than that of the corresponding
centerline lights being tested. In the spring
of 1949 the slopeline system was approved. And
in the spring of 1950 the slopeline system was
given high grades for its performance; however
the evaluating agency was the CAA  who had a
vested interest in a system that they created.
But the approval had little meaning since ALPA
did not relent in its opposition. In addition,
U.K. and France were not enamored of it, and
over 50% of U.S. airports were unable to use the
slopeline system. The CAA reverted to a 1947
arrangement of a single row of lights to the
left of the extended centerline. This was
accomplished by placing the slopeline lights in
a true horizontal plane. But that attempt at a
solution did not succeed.
In 1950 IATA,  after a thorough study,
approved the single-row centerline system which
led to a U.S. centerline system but only after
many years. This was the form favored by U.K.
and various aviation groups for quite some
years. An older version sponsored by  ALPA
lacked condenser discharge lamps but a newer one
contained flashing lights and that has remained
a constant feature over the years. The older
U.K. Calvert system also underwent change: the
five transverse bars were reduced to three bars.
Further complexities were created by various
manufacturers through their diverse designs.
Westinghouse designed neon fixtures and flashing
strobe lights for approach lighting as separate
units (Westinghouse flashing lights were filled
39
with krpton gas and created a flash of as much
as 3.3 billion cp; Sylvania were of xenon gas;
Brightest Lights 1949, 127; see also Centerline
Tests 1950, 50). While Sylvania combined both
in a single fixture. AGA created a funnel
shaped system of steady-burning neon fixtures in
contrast to CAA  funnel system or slopeline
system which displayed groups of sealed beam
lamps; groupings of such lamps continue to be
used in approach lighting. Line Material/Bartow
system created groups dual sealed beam lights in
two lines with four rows of fixtures for the
outermost thousand feet then three rows for the
next segment followed by two and ending with a
single row near the threshold line. The left
line of lights displayed green lights and the
right side red lights; this suggests the pattern
employed in marine channels.
During the time of the experiments at Arcata
and other places, the Aeronautical Board
(members from CAA, CAB, Air Force, Navy, ALPA,
and ATA)  established an approach lighting system
(Army Air Force/Navy/Civil Landing Aids
Experiment Station 1949, 96-153). This system
called for a row of red lights left of the
extended centerline. It is not clear from the
literature how long this system was to be in use
since other experiments were also in progress.
Military airports were to have two rows of
lights: one to be red and one to be orange.
Runway lights were originally semi-flush but
these were gradually phased out in favor of
elevated lights. By 1948 a diverse group of
elevated lights were available for runway
lighting. Bartow and Line-Material promoted a
narrow and "controllable beam" light fixture
while most other makers focussed on high
40
powered, wide beam units that had the side
effects of glare and a halo effect. Kroger
notes that L-M centered on agility through the
controllable beam while the others centered on
using brute force through high intensity beams
(Kroger 1948, 18, 21). Eventually semi-flush
lights were to be reintroduced for inpavement
usage. Runway lights were white in color and
were of several intensities. References for
runway lights include Brightest Lights 1949,
127, New High Intensity Light 1947, 167;
Breckenridge 1955, 13-14, 16; Pilot Guide,
1944, 76, and the already mentioned Kroger.
Other light concerns included threshold and
TDZ areas. ALPA approach lighting schema of
1949 gave a prominent role to threshold lights.
And IATA recommended special threshold lighting
in 1950. TDZ lighting was included in the
Arcata plan for 1949. Slope ... 1948, 16,
Brightest Lights 1949, 127, ALPA ... 1949, 40,
and Moore 1950, 52 are the sources for this
topic.
Radio aids did not follow altogether new
directions in this time. The U.S, radio ranges
continued though they were first threatened and
then overtaken by the VOR system (Wilson 1979,
217-235 TISRP). The CAA was well along withOR
development by 1944 but it was not until 1950
that the first unit was online. The war effort
slowed down considerably the development and
application of the omniranges. By 1952 nearly
400 VOR installations were in service. The ILS
concept existed well into the early 1930s. But
the war again delayed its use. A lengthly
controversy with the military retarded the
acceptance and installation of ILS but
eventually the ILS with its several components
41
dominated the approach phase of air navigation.
DME development gradually moved to joint status
with VOR by 1951.
International cooperation is rooted in the
ealry days of aviation. The first major
conference was held in Paris in 1910 and
resulted in an early air law code. Aviation
concerns were included at the Paris Peace
Conference in 1919. Aviation concerns were
assigned to a Aviation Commission (whose origins
are found in the Inter-Allied Aviation
Committee, 1917) (European ICAO).
This early cooperation led to the
International Air Convention (officially termed
the "Convention on the Regulation of Aerial
Navigation", 1919) which eventually would be
ratified by nearly forty nations (European ICAO;
Hudson, 1931, 359-360ff TISRP). This was the
first full-scale convention on aero naviga-
tion; though the Paris Peace Conference included
provisions on navigation. But the Convention
seemingly gave scant attention to navigation
aids. There are references to radio communi-
cation but seemingly these had little to do with
radio navigation aids. A single reference to
visual aids is found in the Convention (Chapter
IX, Article 35 (b)). A series of Protocols
between 1920 and 1929 does not approach visual
aids either. It is conceivable that ICAN went
beyond the specific provisions of Convention and
Protocols and addressed visual aids more
thoroughly. A listing of other agreements (up
to 1930) do not indicate evidence of an
inclusion of navigation aids either. The
agreements in question included both general
participation and bipartite forms (List of
International Agreements ...).
42
The Convention dealt with all aspects of
civil aviation and led to the establishment of
the International Commission for Air Navigation
(ICAN). The Commission added a Secretariat in
Paris and after the creation of ICAO the offices
of the Secretariat housed the European quarters
of ICAO for nearly two decades (European ICAO,
"ICAO Forty Years of Air Navigation in
Europe").
An event of greater significance for
aviation and aero navigation aids is the
establishment of the International Civil
Aviation Organization (ICAO) and its predecessor
the Provisional Civil Aviation Organization and
the International Civil Aviation Conference in
the 1940s. The U.S., upon requests from U.K.
and Canadian governments, called for an inter-
national conference in September of 1944 that
lead to the formation of PICAO/ICAO. Principal
sources included Henry Ladd Smith 1950 and
Proceedings of the International Civil Aviation
Conference.
The conference began on November 1, 1944 and
ended on December 7 of that year. A great deal
of disagreement between the participants,
specifically between the U.K. and U.S. occurred;
some of which became acrimonious. Progress was
virtually nonexistent for weeks. On December 2,
an Air Transit agreement was signed and that
signalled the end of paralysis: within five days
several other documents were completed. These
included Appendix I, Interim Agreement on
International Civil Aviation; Appendix II,
Convention on International Civil Aviation;
Appendix III, International Air Service Transit
Agreement; Appendix IV, International Air
Transport Agreement. Appendix V included 12
43
technical annexes which were to become part of
the Convention at a later date.
Most significant was the International
Convention on International Civil Aviation.
Provisions included air transport, navigation,
technical matters and included provisions for
setting up ICAO. Three years were available for
ratification. In the meantime work continued
under the Interim Agreement on International
Civil Aviation which had established PICAO. In
many ways  the agreement was similar to the
Convention but narrower in scope. The major
event after the ending of the Conference was the
revision of Appendix V including navigation
aids. PICAO had an interim assembly, interim
council, three principal committees and a
secretariat. In 1946 PICAO adopted U.S. radio
standards as its own. ICAO began existence in
its own right in 1947.
ICAO includes 15 annexes to the Convention
on International Civil Aviation. Those
important for this study are Annex 10,
Aeronautical Telecommunications, and Annex 14,
Aerodromes. The appendix of this study takes up
a review of navigation aids and their changes
from the late 1940s to the present.
Epilogue
U.K. had a centerline approach system in the
1940s known as Calvert (E.S. Calvert was
principal scientific officer at the Royal
Aircraft Establishment; worked on centerline and
crossbar lights, also taxiway lighting and
runway markings; see Four Honored 1951, 19).
ICAO came to an agreement in 1952 on a
centerline system and established a standard for
44
that system. Work on centerline systems was
well underway in the U.S. in the early 1950s
including much of the design work and necessary
equipment. But it was not until the late 1960s
that the U.S. had an officially agreed upon and
functioning approach light systems. A truly
incredible misadventure marked every stage of
fumbling U.S. efforts. Older French system
consisted of a left-hand row of lights 100
offset of the centerline (CAA Withdraws 1950,
15)
In 1951 it was noted that U.K. had long had
a centerline system and U.S. pilots favored that
approach. Tests of ideas took place over and
over again. In 1951 the tests were at Patuxent
Naval Air Station. International conferences
twice took place during 1951. The problem was
four-sided: U.S. Air Force, U.S. Navy, CAA and
the civil airline pilots. CAA had already given
up slopeline and waited agreement from the other
three groups. Navy still wanted slopeline while
the pilots wanted centerline. The Air Force
forbad any centerline for the first 1000 feet
from the end of the runway; they would allow an
extension of red runway edge lights within that
zone. It was thought possible that order out of
chaos might be achieved during 1951; similar
optimistic statements were repeatedly made over
the years. A compromise seemed possible with
centerline at civil airports and a modified
version at Air Force facilities. This imbroglio
blocked international acceptance of an approach
light system (New Hope ... . 1951, 16).
In 1952 the situation was unchanged. More
evaluation resulted in strong pilot support for
centerline and dissent from the military. CAA
remained indecisive even though the evaluation
45
of pilots was conducted by the CAA. ICAO was
due to take up the centerline question in 1952.
Nothing had changed from previous evaluations,
testing, and attempts at reaching agreement
(Pilots, ATA . 1952, 75-76).
According to AW, technical representatives
agreed on centerline at ICAO 1952 though the
general membership had yet to vote. Supposedly
the U.S. military withdrew opposition to
centerline approach yet the impasse went on.
Though ICAO sources indicate that a standard for
approach lighting was adopted in that year
(Centerline Lights . 1952, 14; Airports
1953, 23).
1955 led to no agreement but it did lead to
more tests. This time at McGhee-Tyson air base
at Knoxville TN. It was thought that the
stalemate could be resolved. A 3000 foot
centerline system was the focus of the tests.
Both centerline and one of 3000 foot length
recur in the literature year after year as often
as reports of no agreement occur (USAF, CAA Test
. 1955, 131).
In 1956 an approach light system known as
"U.S. National Standard Configuration  was
installed at Idlewild Airport. It had a single
cross bar and was inferior to the later March
experiment. Strobe lights were a prominent
feature of this system (termed Electronic Flash
Approach System or EFAS). The National Standard
consisted of two patterns in 1955: "A" with a
3000centerline and "B" with a 2000centerline
(USAF, CAA Test ... ." 1955, 131).
More tests were conducted in 1957. These
took place at March Air Force Base in
46
California. Much of the focus was on flashing
strobe lights though the tests were important
for a more basic matter: USAF finally permitted
centerline lights close to the end of the
runway. This seemingly opened the way to
approval of a centerline system. The March
tests also included the curious red approach
edge lights which gives the inner 1000 feet a
three-pronged appearance. The March
configuration increased usage of cross-bars
(termed roll-bars at that time) (Christian 1956,
96-97). Two components to this lighting system:
Sylvania Strobeacons and "Elfaka Flush
Lighting"; the latter consisted of concrete
boxes with metal grids set into the runway
pavement with Sylvania or GE lamps set inside.
These units were also employed for threshold
lighting (older threshold units were fewer in
number and more difficult to identify) (USAF
Pilots ...  1957, 117). The Dutch firm Elfaka
approach contrasted with a British idea
utilizing a iron hood over an inset light
fixture (CAA Will Test 1956, 34).
Captain R.C. Robson, in a column known as
"Cockpit Viewpoint", spoke on "The Same Old
Story" in February of 1959. A friend and 64
others had died in the crash of a Lockheed
Electric shortly before. Robson thought that
pilot error would be the official version of the
cause but he blamed inadequate visual aids and
in particular an adequate approach light system.
1959: the issue is not yet settled (Robson 1959,
43).
IES Lighting Handbook  in 1966 spoke of
approach lighting systems and of "standard
approach lighting configuration." The standard
system was a centerline system with one cross
47
bar and it could exhibit flashing lights. But
it does not appear to have been an officially
sanctioned and agreed upon system though it was
substantially closer to that state (IES 1966,
21-7 to 21-9). By the 1972 edition approach
lighting in the U.S. had taken on its familiar
and current appearance (IES 1972, 21-6 to 21-9).
FAA documents suggest 1969 was the beginning of
an official documented system though alterations
were on occasion made (FAA 1969; FAA 1974).
48
CHAPTER 34
THE CLASSIFICATION
34A Main Classification Explanatory Notes
34A1 Introduction
The main classification is largely based on
publications of ICAO. The accompanying variant
classification in Ch 34B will include variants
of markings in the main classification, and
markings from other standards (FAA and NATO
augmented by national and manufacturers
resources). The classification has been easier
to construct and less complex than that of
International Railway Signals  (Part F) since
that study was built up from many sources as
railway signals - contrary to aero aids - lacked
an over-arching central source of information.
There is a danger in saying that Part G
classification is simple and easy of construc-
tion since such an attitude can lull one into
overlooking variant and nuanced forms. Even the
forms that are included do not include requisite
details and qualifications. Those omissions are
addressed by explanatory notes and the variant
classification.
The classification of Part B, (2nd ed)
truncated some forms of navigation aids when
those aids shared a common lamp apparatus. For
example, Medium Intensity Runway Edge and
Threshold/end and Taxiway lights employ the same
fixture (#3232 in that classification). While
49
that approach has some merit (it recognizes that
a single form of marking may have multiple
functions) it is questionable in that a specific
form of marking has - to employ a biological
term - both physiological and morphological
dimensions. One apparatus, when used for
different functions, is not identical. The
message is not the same, and the means for
creating and projecting that message has to be
at variance. Therefore, in this classification,
separate entities serving different functions
with nearly identical physical equipment will  be
regarded as separate in the main classification.
Classification nomenclature can be an
unwieldly and cumbersome process: it is nearly
impossible to fully root out errors and
oversimplifications. That can be seen very
clearly in the meaning of "partially-lighted"
when applied to marine aids to navigation, and
aero navigation aids. Partially-lighted follows
the literal meaning for marine aids: an aid
partly-lighted and partly unlighted. For
example, a harbor light has both a lamp
apparatus but it also has a daymark; both are
essential though the light may eclipse the day
portion.
But for many aero aids there is no day
portion (obstruction aids are an exception) that
is an integral part of the marking. Aero lights
are complete in themselves, and nearby markers,
pavement markings and signs are separate aids.
Partially-lighted therefore means a light
burning part of the time instead of an aid
displaying both a lighted and unlighted aspects.
The explanatory notes are relatively brief
for this classification. The presence of a
primary source reduced the need for extensive
50
notes as was the case with Part F which lacked
such a source. The variant classification and
its note (Ch 34B) and Chs 35-37 augment the
material of Ch 34A.
34A2 Main Classification
31 All-lighted
310 Approach Lights
3100 High Intensity Unidirectional
Elevated Lights
3101 Medium Intensity Omnidirectional
Elevated Lights
3102 Capicitator-discharge Lights
3103 Helicopter Approach Lights
311 Final Approach Indicators
3110 VASIS
3111 3-Bar VASIS
3112 T-VASIS
3113 PAPI
3114 HAPI-PLASI
32 Partially-lighted
320 Runway Inset (Inpavment) Lights
3200 Threshold Identification Lights
3201 Edge Lights
3202 Threshold Lights
3203 End Lights
3204 Centerline Lights
3205 Touchdown Zone Lights
321 Taxiway Inset (Inpavement) Lights
3210 Taxiway Centerline-straight Lights
3211 Taxiway Centerline-curved Lights
3212 Taxiway Centerline-intersection
Lights
322 Runway Taxiway Elevated Lighting
3220 Runway Edge Light
3221 Runway Threshold Light
3222 Runway End Light
3223 Taxiway Edge Light
51
3 224  Holding Position Light
3225  Stop Bar Lights
3226  Stopway Lights
3 227  Clearance Bar Lights
3228 Helicopter Final Approach 
Take-off Area Lights (Edge)
3229 Helicopter Touchdown Lift-
off Area Lighting Systems (Edge)
323 Beacons
3230  Aerodrome
3231  Identification
3232  Heliport
324 Obstruction Lighting
3240  Low Intensity
3241 Medium Intensity
3242  High Intensity
325  Indicators
3250  Wind Indicators
3251  Landing Direction Indicators
326  Parking Docking Aids
3 260  Aircraft Stand Manouevring Guidance
Lights
3261 Visual Docking Guidance System
Special Dual Classification For Signs:
32 Partially-Lighted  33 Unlighted Aids
325/330  Illuminated
Non-illuminated Signs
3250/3300  Mandatory Instruction Signs
3251/3301  Information Signs
3252/3302  Aerodrome Identification Signs
3253/3303  Aircraft Stand Identification
Sign
326  Helicopter Colocated Aids
3260 Aiming Lights Markings
33  Unlighted Navigation Aids
330  Runway Markings
3 3 00  Runway Designation Marking
52
330 1  Runway Centre Line Marking
3302  Threshold Marking
3303  Fixed Distance Marking
3304 Touchdown Zone Marking
3305  Runway Side Stripes
331 Taxiway Other Markings
33 1 0  Taxiway Centerline Marking
33 1 1  Taxiway-Holding Position Marking
33 1 2  Taxiway Intersection Marking
33 1 3  VOR Aerodrome Check-Point Marking
3314 Aircraft Markings
3315  Apron Safety Lines
332  Helicopter Markings  Markers
3320 Winching Area Markings
332 1  Identification Marking
3322  Mass Marking
3323  FATO Marking/Markers
3324  TD Markings
3325  Heliport Name Marking
3326  Helideck Marking
3327  Taxiway Markings
3328  Air Taxiway Markers
333  Markers
3330  Unpaved Edge Markers
3331  Stopway Edge Markers
3332  Snow-covered Runway Edge Markers
3333  Taxiway Edge Markers
3334  Taxiway Centre Line Markers
3335  Unpaved Taxiway Edge Markers
3336  Boundary Markers
334  Obstruction Markings
3340 Patterns
3341 Sphericals
3342  Flags
34  Electronic Navigation Aids
340 Fully-Integrated Systems
3400 Localizer, ILS
3401  Glide Path, ILS
3402  Marker Beacons, ILS
53
3403 Azimuth Station, MLS
3404 Elevation Station, MLS
3405 Distance Measuring Equipment (DME),
MLS
341 Independent Partially-Integrated
Aids
3410 VOR
3411 DME
3412 Loran-A
3413 Consul
3414 Non-Directional Beacon (NDB)
3415 En-route VHF Marker Beacon
34A3 Explanatory Notes
31, All-lighted. Approach and Final
Approach lights are on at all hours. They are
not partially-lighted aids in contrast with most
aero navigation aids. Approach lights, 310, are
in three forms: 3100, unidirectional high
intensity form light; 3101, omnidirectional
medium intensity light; and 3102, the
capicitator- discharge flashing light which
carries out several functions.
Approach lighting is something of a problem
in that ICAO does not speak of high intensity
unidirectional and medium intensity omni-
directional fixtures for approach lighting.
Yet, according to ADB, Thorn and Slo-Idman those
characteristics are found with  ICAO sanctioned
approach lighting and therefore they are
included in the classification.
Final Approach Indicators 311, encompass a
variety of lights with overlapping functions
and divergent names that include several key
words: indicator, visual, slope, path, descent,
glidepath, glideslope. Many of these are found
54
in the Variant Classification. A core element
is the VASI or Visual Approach Slope Indicator,
3110, which is becoming obsolescent; only the
parent form is in this classification. The
T-VASIS is included in Main rather than in
Variant because it follows a substantially
different primary coding principle and yet
retains official status for ICAO.
PLASI, or Pulse Light Approach Slope
Indicator, is a U.S. developed aid that has
nevertheless found employment in a variety of
nations (FAA 1988 A/C 150/5345-52; see also
Devore 1991). So far, it is not included for
ICAO approved aerodrome operations. But a
version, HAPI-PLASI, 3112, has been so approved
by ICAO. It is a variant of HELI-PLASI a
configuration of PLASI. The other PLASI forms
are in the variant classification since they
lack ICAO status.
32, Partially-Lighted. This has a somewhat
different meaning than in marine aids. Aero
lights of this form lack a day dimension; the
day indication is a separate aid. There are six
divisions in 32: inset (runway,and taxiway),
elevated, beacons, obstruction lights, wind
indicators, and parking and docking aids
(lighted signs are handled separately)
The classification is simple to the point of
the basic divisions of types of lights, but then
complexity develops: landing aids, runway lights
and taxiway lights encompass a variety of
functions but many of the lights are very
similar and some forms are identical. Since
this classification focusses on the physical
rather than on messages the point of
differentiation will be that of the physical.
Since landing aids are related to runway
55
functions they are part of runway categories.
There are many forms of inpavement (inset)
lights so that taxiway and runway forms have
been placed in separate though adjoining
categories. Elevated forms are fewer and
therefore runway and taxiway lights are united.
Categories of aviation (Category I, II, III)
and light intensity (which is, to some degree, a
reflection of category) affect the light
equipment of 320, 321 and 322 but not this
classification. The variant classification and
Chapter 35 will include the factors of category
and intensity.
ICAO offers many substantial information on
approach and final approach lights. But
material on beacons, by contrast, tends toward
the sparse and restricted to salient points
only. ICAO speaks of a single beacon but in
practice there are higher and lower intensities
and designs are affected by this fact. But a
single category is sufficient for Main. As a
result a wide latitude in beacons forms, -
especially aerodrome beacons, 3230 - is
possible. At least two manufacturers have
produced a beacon in the shape of a square box
and the beacon of another manufacturer bears a
resemblance to a giant alarm clock. This
latitude restricts this classification, and also
that of the variant classification as well since
the classification becomes either vague or
burdened with minutiae. The identification
beacon, 3231, is closely related to the old U.S.
code beacon and that design is agreed upon by
various makers to a considerable degree. The
design of the heliport beacon, 3232,
demonstrates the same consensus among
manufacturers.
56
Obstruction lighting, 324, judging by trade
literature shares points of design. The simple
low intensity form, 3240, appears to be of a
nearly universal shape. Medium intensity, 3232,
follows the code or identification beacon form
or a newer capicitator-discharge design which
appears similar to many river and harbor light
design. High intensity, 3233 forms are similar
in design which is that of a shallow metal box
displaying linear flash lamps.
322, Inset Lights. ICAO employs the terms
inset or surface lights. U.S. practice termed
these semi-flush at one time but has changed
that to inpavement lights. NATO employs inset
but also includes semi-flush and even blister
lights. Ulmer Aeronautique presents a curious
form known as "semi-buried" ("semi-encraste")
which have the shape of the inset form but are
slightly above ground. Ulmer refers to inset
forms as the buried or encastre form. Inset is
retained as a second term in the main
classification. Pollock speaks of full-flush
and semi-flush (Pollock 1990, 38). ITTE adds a
nuanced meaning by referring to lights placed in
the runway (but not along the edges) as
in-runway lights (ITTE 1962).
"Indicators" is a common term for aero aids
though it can prove to be a difficult one to
define. It often refers to aids that have a
precise nature and aids requiring a precise
response. For example, final approach
indicators, a fully-lighted aid, requires a very
precise and narrowly focussed response from an
aircraft pilot. This segment, however, refers
to aids that are not fully-lighted and may not
be lighted at all. There is a problem of
classification for these indicators, 325, since
one element can be either lighted or unlighted
57
though more often it is lighted while the other
element can be lighted or unlighted with the
unlighted version a fairly common form. The
former refers to the wind indicator, 3250, and
the latter refers to the landing direction
indicator, 3251. The situation is akin to that
of signs. For this classification both are
listed as partially-lighted aids though an
unlighted version can not be ruled out.
326, Visual Parking Docking Guidance
systems includes two very different systems and
both are included in the main classification.
3260, Aircraft Stand Manoeuvring Guidance
Lights, 3260, display standard inset taxiway
ways. Visual Docking Guidance System, 3261,
displays alphanumeric and graphic symbols. They
are included together since they have similar
functions. VDGS is also present in the variant
classification.
32/33, Special Dual Classification. In an
attempt to resolve the issue of signs that are
sometimes partially-lighted and sometimes
fully-unlighted a dual approach is proposed here
that resides on/crosses the boundary between
partially-lighted and unlighted. This
acknowledges the special situation engendered by
signs but does not try to resolve it by deciding
which are partially-lighted, which are
unlighted, which can be either or both.
Non-sign markings are of four general types.
The first type, Markings, 330/331  are, to a
substantial degree in a paint medium. The
markings frequently display stripe and band
configurations; though some are in alphanumeric
forms. Traffic control devices pavement
markings are closely allied to these aids.
Markers, 333, are multidimensional and most have
58
a vertical aspect. The one exception is that of
Taxiway Centerline Markers, 3324, which are
low-level aids jutting only slightly above the
surface. Helicopter markings markers, 332, is
a relatively small area yet a complex one. Some
abbreviated and conflated categories have been
included for this general classification.
Obstruction Markings, 333, include both one
dimension and multi-dimensional forms are in
use. These diverse aids are connected by a
shared function: denoting obstacles to
navigation. Some are in a paint medium while
others take on the form of spheres or flags.
34, Electronic Navigation Aids. This
classification centers on individual
transportation markings. However, many
electronic aids are parts of systems and the
individual aids are subsumed under the system
identity: ILS and MLS. ILS encompasses
traditionally name aids, 3400, 3401, and 3402.
However, ICAO includes MLS functions rather than
names of aids; this also the practice of
manufacturers. Some sources give the specific
names including Pierre Condom  (Interavia  1985,
879-881). MLS aids are designated 3403, 3404,
and 3405.
Independent and Partially-integrated aids
includes a diverse group of radio aids.
Loran-A, 3412, and Consul, 3413, are marine
both in foundation and in sponsorship but they
are included here because of inclusion by ICAO.
NDB, 3414, and the En-route VHF Marker Beacon,
3415, are airport aids as well. These specific
versions are away from the airport area and can
be regarded as separate aids since they have
divergent functions.
59
34B Variant Classification Explanatory Notes
34B1 Variant Classification
31 All-Lighted
310 Approach Lights 311 Final Approach
Lights
.1 Light Fixtures/Functions/Systems: Approach
Final Approach
.10 Approach Light Equipment
.100 High Intensity Unidirectional
Lamp (Halogen)
.101 High Intensity Unidirectional
Lamp (Par 56)
.102 Medium Intensity Omnidirectional
Elevated Lamp (Halogen)
.103 Medium Intensity Omnidirectional
Elevated Lamp (PAR 38)
.104 Low Intensity Omnidirectional
Elevated Lamp (Halogen)
.105 Omnidirectional Flashing Lamp
.106 Unidirectional Flashing Lamp
.11 Flashing Lights By Function
.110 Runway Threshold Identification
Lights (RAILS)
.111 Runway End Identification Lights
(REILS) Omnidirectional
.112 Runway End Indentification Lights
(RAILS) Unidirectional
.113 Runway Identification Lights
(RILS)
.114 Runway Alignment Identification
Lights (RAILS)
60
.12 Approach Lighting Systems: ICAO NATO
.120 Simple Approach, ICAO
.121 Precision, Category I
.122 Precision, Categories II III
.123 Type I, NATO
.124 Type II, NATO
.125 Simplified Type, NATO
.13 Approach Lighting Systems: U.S. FAA
.130 ALSF-I
.131 ALSF-II
.132 SSALSF
.133 SSALR
.134 ODAL
.135 MALSR
.136 MALSF
.14 Final Approach Equipment:
Color Coding:
.140 APAPI (2-Color/1 Proj)
.141 H-PAPI (2-Color/1 Proj)
.142 Mini-PAPI (2-Color/lProj)
.143 AVASIS (2-Color/2 Proj;
4 versions;)
.144 SAVASIS (2-Color/2 Proj)
.145 3-Bar AVASIS (2-Color/2 Proj)
.146 CHAPI (Tri-Color/1 Proj)
.147 Glide Path Indicator (Tri-
Color/1 Proj)
.148 T-PASI (Tri-Color/1 Proj)
.15 Final Approach Equipment: Pattern,
Pulse Alignment Coding
.150 AT-VASIS (Pattern)
.151 PLASI (Pulse)
.152 HELI-PLASI (Pulse)
.153 HAPI-PLASI (Pulse)
.154 Optical Localizer
.155 (Alignment of Elements,
Partially-lighted)
61
32 Partially-Lighted
321 322  Runway Taxiway Lights; 323 Beacons;
324 Obstruction Lights; 325  Indicators
.2 Light Fixtures: Selected
.20 Taxiway Inset (Inpavement) Lights
.200 Straight Sections Caution Bars
(Other than Category III)
(Bi/Uni)
.201  Straight Sections Caution Bars
(Category III) (Bi/Uni)
.202  Intersections (Other than
Category III) (Bi/Uni)
.203 Intersections (Category III)
(Omni)
.21 Elevated Lights
.210 Runway Edge (VFR)
.211 Runway Edge (NP IFR)
.212  Runway Edge (P IFR)
.213 Threshold/End (VFR)
.2 14  Threshold/End (NP IFR)
.2 15  Threshold/End (P IFR)
.22  Beacon Lights
.220 Medium Intensity
.221 High Intensity
.23  Obstruction Lighting,
.230  Incandescent Bulb/External Lens -
Low Intensity (L.I.)
.231 Incandescent Bulb/Internal Lens -
L .I.
.232  Mercury Bulb/External Lens - L.I.
.233  Neon Tube/No Lens - L.I.
.234  Fresnel Double Drum Lens - Medium
Intensity
.235 Multi-Cold Cathode Tubes 
Reflectors - M.I.
.236 Strobe Light, Helical - M.T.
62
.237 Strobe
M .I.
Light, Linear Flashtube
.238 Strobe
Double
Light,
Unit -
Linear Flashtube
M.I.
.24 Docking Systems
.240 Numeric, Signal Graphic form
.241 Alpha, Signal Graphic form
3. Vertiport Lighting Markings
.300 Identification Beacon
.301 FATO Lighting
.302 TLOF Lighting
.303 Identification Markings
.304 TLOF Markings
.305 FATO Markings
34B2 Explanatory Notes
Approach Lighting proves to be an especially
complex subject. There are many configurations
and possible variations for ICAO alone and
differences outside of ICAO can be even more
extensive. The variant classification is
intended to focus on physical differences in
equipment. Yet approach lighting equipment can
frequently be similar though great differences
in configurations and terminology can be
present. For those reasons this variant
classification takes up approach lighting
apparatus that may differ by terminology or use
even if not by physical characteristics. Much
of the variant classification is given over to
approach lighting. That coverage is divided
into .10, Lamps and  lampholders; .11, flashing
lights by function; .12 approach lighting
systems for ICAO and NATO; and .13 approach
lighting systems for the U.S.
The many light units (lamp and lampholder)
at an airport represent only a few kinds of
-
-
63
light fixtures. And the differences in light
units may often not be that significant.
Nonetheless the various forms of fixtures, types
of lamps, functions and systems are all included
here. ICAO technical specifications are less
detailed than national specifications since they
encompass broad requirements and they center on
characteristics of fixture and lamps and on
colorimetry expectations. Therefore, the
catalogues of manufacturers have had a role in
this coverage since they translate ICAO
standards into concrete descriptions and images.
This is true for all forms of aero lights and
not merely approach forms.
RTIL (110) and REIL (111) (and presumably
RIL, 112, as well) belong together. They are
flashing lights flanking the threshold lights.
But ICAO places RTIL with runway related lights
while the FAA places REIL with approach
lighting; NATO RILs also appear to be with
approach lighting. RAILS (113) are flashing
lights situated below the starting point of
Medium Intensity Approach Lighting systems in
the U.S. RTILS are unidirectional only but
REILS and RAILS can be omnidirectional as well.
All of these lights, some unidirectional, some
omnidirectional are closely allied though use
and designation may create a contrary
impression.
Approach lighting systems are closely
integrated systems choreographed according to
structured rules. The various systems are
included in this variant classification because
they have great bearing on the physical
apparatus and because a fuller comprehension of
the apparatus and messages can be gained through
knowledge of the systems. Segment .12 includes
ICAO and NATO forms. NATO and ICAO each have
64
three forms and they bear strong resemblance to
one another.
ICAO Precision Category II III (124) has
two possible configurations: barettes (light
bars) or individual light fixtures. When the
later is employed there is a triangular shape
created since the various rows of light fixtures
decrease toward the runway threshold while
barettes have the same number of lights in each
row. The barette form seems far more common.
U.S. FAA, .13, approach light systems may
seem at sharp variance with ICAO and NATO
systems. However, the variation may not be all
that much. All of the systems are centerline in
form and bear considerable resemblance toward
one another. The names and acronym do project
distinctly different images. U.S. Medium
Approach Lighting System (MALS) is similar to
Category I rather than the ICAO simplified
system. There is in fact no comparable U.S.
system to the simplified system. Halogen lamps
are commonplace in many systems though PAR 56
continue to find considerable use. PAR 38
continues to dominate in the U.S.
The coverage of final approach indicators is
at variance with the usual Explanatory Notes
format. There are many forms of these
indicators. In many instances no longer employed
forms contribute greatly to currently employed
forms. Indicator forms, both new and old, exist
under a thick covering of acronyms that have
become interwoven with the indicators. Final
approach indicators are divided into two
segments: .14 for color coded forms (individual
forms are marked for number of colors and number
of projects), and .15 for pulse, pattern and
alignment forms. A description of the workings
65
of various glide slope indicators is to be found
in Cook review of landing aids development
(Cook 1960, 108-110).  Some case can be made for
Slopeline to be considered as an indicator. See
Approach Light Systems 1950, 46-47.
Two-Color and Single Projector units include
PAPI, APAPI and H-PAPI. PAPI is assigned to the
Main Classification. APAPI, .150, (first A in
APAPI designates Abbreviated) has two light
units instead of four and displays three
messages instead of five: too low, correct path
or high (PAPI has two low messages: quite low
and slightly low and two high messages: quite
high and slightly high). H-PAPI, 151, has the
messages of APAPI but in a different
configuration: the light units are at the end of
the landing area flanking the centerline instead
of alongside the runway area.
Two Color and Multiple Projectors include
VASIS, AVASIS, SAVASIS, 3-Bar VASIS and 3-BAR
AVASIS. VASIS is in Main as well as 3-Bar
AVASIS (ICAO includes that aid with VASIS and
PAPI as principal forms of final approach
indicators). AVASIS, .142, forms are on one
side of the runway and have from two groups of
one light each to two groups of three lights
each. U. S. configurations for VASIS  are at
variance with those of ICAO. The U.S. standard
patterns more adequately conform to AVASIS
standards while variant patterns include both
VASIS and AVASIS forms. SAVASIS, .143, appears
to be closely allied to an ICAO two fixture
AVASIS of reduced power. 3-Bar  AVASIS is
designed as .144.
Tri-color aids provide a degree of
uncertainty: one can speak in generic terms or
resort to specific terms which are brand names
66
or nearly so. T-PASI, .148, (Danaid) and Glide
Path Indicator, .147, (Cegelec) are single
projector and single unit aids. CHAPI, .146,
(Crouse-Hinds) is a single projector but
multiple unit operation. The first two display
colors of yellow, green and red. CHAPI displays
white, green and red indications. All three
have precision optics.
Pattern Coding consists of T-VASIS and the
variant form of AT-VASIS, .150. T-VASIS is
found in Main. TVG (T-Visual Glide Slope) was
the Australian name but ICAO designated it as
T-VASIS. It retains official standing unlike
VASIS. RT-VASIS or Reduced T-VASIS was an
attempt to reduce the system to six boxes on one
side of the runway (AT-VASIS has ten boxes on
one side) but that attempt was not successful.
Pulse Coding offers an alternate to PAPI
though for more restricted usage. ICAO has not
approved it for aerodromes but one version is
approved for heliports; that formed is termed
HAPI by ICAO and HAPI-PLASI, .153, by Devore
Aviation the sole manufacturer. An earlier
version, HELI-PLASI, .152, displays white/
green/red messages while HAPI-PLASI has
yellow/green/red messages. The core form at
present is that of PLASI, .151, (Devore
Aviation). Glide Angle Indicator Light (GAIL)
and Visual Approach Path Indicator (VAPI) are
older pulse code aids.
Alignment Coding, .154, has had a long
history in final approach indicators. Possibly
the only such system in use is that of GLISSADA
from Russia. An Alignment of Elements system is
a day system that can be enhanced for night use
with lights. AOE is therefore either a
partially-lighted or unlighted system and apart
67
from fully-lighted forms. MDLA (Mirror Deck
Landing Aid) is an older form of alignment
coding. FLOS (Lens Optical Landing System),
Poor Man Optical Landing Aid (POMOLA) and
Double Bar Ground Aid (DBGA) are variants or
derivatives of MDLA.
There are other many forms of final approach
indicators. Some are largely terminological
phenomena, some are variant forms, yet others
are defunct forms while still others have
contributed features to newer and extant forms.
Visual Glide Path Indicators (VGPI) and Angle of
Approach Indicators (AAI) contributed to TVG
which eventually was termed VASI. What has been
termed Tri-Color VASI is a generic term rather
than specially a VASI system; it encompasses the
three-color, single projector aids (GPI, etc).
Terms such as Pulse Code Optical Landing
Aids (PCOLA) Optical Projector Ground Aids, and
Generic Visual Descent Indicators (GVDI) are
overarching terms more than specific indicator
form. GVDI is the FAA designation for indi-
cators for general aviation and includes VASI
(two projectors) and PLASI forms (one
projector).
ICAO refers to different situations for
runway and taxiway lighting (curves, straight
sections, exits) but does not mention various
types of lighting to meet those needs. Neither
does NATO whose coverage is similar to that of
ICAO. The U.S., in marked contrast, has a great
mass of detail on variant forms of runway and
taxiway lighting. For that reason the coverage
for runway and taxiway, and these notes, focus
on the U.S. situation. Not all forms of runway
and taxiway lighting requires inclusion in this
classification since some forms lack significant
68
variant types. Taxiway inpavement lights are
listed under .20 and elevated lights (runway,
and threshold/end are designated as .21.
Obstruction lighting has three levels of
operation with a variety of types of apparatus
for each level. National standards may narrow
the range of design but ICAO standards are
directed more at optical capabilities than the
physical design of the device with the end
result of light units of diverse appearances.
The variant classification now encounters a
problem: if the classification is predicated on
optical abilities then it obscures the physical
designs but predicating the classification on
the ingenuity of manufacturers can result in a
bewildering range of designs. The variant
classification has attempted to answer this
dilemma by incorporating key elements of optics
and designs augmented by appropriate notes. All
obstruction lights are subsumed under .23.
The American model of the basic fixed, low
intensity obstruction light varies little from
maker to maker: its overall dimensions are often
little more than 5" in diameter and 7" in
overall length (including lampholder), it is of
glass and has a Fresnel type of lens as part of
the globe; there is usually no dome over the
lens. This model employs an incandescent globe.
European makers frequently offer this model or
one similar. But they also offer many other and
distinctly different forms as well. Some models
are somewhat similar with more muted changes: an
egg-shaped globe instead of one that is
cylindrical or a clear dome over the lens or a
partial lens. The basic form is designated as
.230; an internal lens form becomes .231. And a
form with partial lens and mercury lamp is
listed as .232. Differences in shape of the
69
globe or lens were not deemed sufficient to
warrant a separate number.
Many European forms are radically different.
These are often employ neon tubing (a form of
cold cathode tubing), they may be elongated,
often without any lens, they may even be
attached directly to a power line. Some forms
have a similar glass dome surrounding the neon
tubing. Mercury lamps have also been employed
in some instances. All of the neon obstruction
lights are listed under .233 though further
differentiation may be justifed.
Medium Intensity forms traditionally have
employed what is frequently termed the code
beacon: a double cylindrical drum in the Fresnel
mode with an incandescent bulb for each part of
the drum lens. This unit, designated as .234,
in red, continues to find considerable use in
many parts of the world. But other forms of
medium intensity have been developed. These are
frequently strobe lights with  helical flashlamps
and are very similar to marine aids to
navigation lights. They are omnidirectional
with a white flash tube. Cegelec has produced
an additional medium intensity form: a unit
utilizing neon tubes, .235, coupled with
anodized reflectors;
A new form of medium intensity obstruction
light, .237, uses multiple linear flash tubes
with reflectors creating omnidirectional
coverage. The older flashtube light, .236,
employs a singular helical flash tube for
achieving omnidirectional coverage.  A variant
form, .238, has two sets of linear
bulbs/reflectors with a double cover: one part
clear and one part red. This approach
eliminates a separate traditional red beacon for
70
night use. High intensity beacons are all of
the strobe lamp variety and do not require
coverage in the variant classification.
Beacons for airport indentification project
an uncertain image since they perform a role
from through different designs and equipment.
In a brief study the only distinction may be
between medium intensity, .220, and high
intensity, .221. The high intensity forms,
whatever the design employed, are found at major
airports and display powerful lights. Medium
intensity units, with a variant form at
heliports, are somewhat smaller in design and
power. Many medium intensity forms have two or
three separate lights in one unit while high
intensity have a single and integral apparatus.
Docking systems are elsewhere included with
Runway and Taxiway forms due to functional
similarities. But they remain a separate entity
in equipment. One form, .240, employs numbers,
standard signal lamps and graphic symbols but no
words while the other, .241, omits number forms
but includes words in conjunction with signal
lamps and graphic symbols.
Vertiport Lighting and Marking is included
here because it originates with U.S. FAA not
ICAO. The classification presents only the
general forms of these aids. Ashford Wright
1992, 470-473).
71
L
34C Pictorial Representations
34C1 Illustrations
Inset Forms
72
 
0 0 0- 
Approach & Final Approach Forms
73
Beacon & Obstructions Light Forms
74
Runway and Taxiway Light Forms
75
rn
MOMOM
Kin
17-1 ww.
VOR  116.3  1 4T VOR 116  31,
147
NO ENTRY
ARCATA
Signs and Markings
77
34C2 Explanatory Notes
Instantly recognized aero aid forms are
probably the exception not the rule. This is due
to several factors: international standards
which are less detailed than national standards,
changes in optics, expansion computer
technology, and new developments in plastic,
glass and metal. Hence the illustrations in
34C1 and these Notes can only be representa-
tive within restricted bounds. Older forms were
often identical or at least substantially
similar, but this is now less often the case.
The Notes cannot cover all cases because of the
brevity of the study. Nonetheless, Chapter 34C
presents a preliminary illustrated introduction
to the topic of aero aids.
Inset forms can be divided into three types:
omnidirectional, bidirectional and uni-
directional. Omnidirectional types are
represented by two forms: a simple form with a
clear glass center (top left, graphic
representation; see Idoman, Cegelec, ADB, among
others) that radiates light in all directions
and a more substantial form (top left,
Crouse-Hinds) that can bear up under weight and
which throws light energy from a segmented lens.
Multiport lens continue to be common from
European (ADB, Idoman) manufacturers though less
so in the U.S. Only one of the manufacturers
represented in this study offers a triple-port
light (upper left central). That is Thorn
Europhane and the light is employed for approach
and threshold lights. Doubleport lens are
commonplace and may be either bidirectional or
unidirectional (left lower central). They may,
depending on maker and function, be shallow or
78
deep units; they may also be wide or narrow.
Two illustrations display singleport units. One
is offset and that seemingly is found only with
with Crouse-Hinds (right upper center). The
wide yet shallow unit (bottom right) represents
lens openings that may be on the edge of the
housing as well as those set in slightly from
the edge (patterned on Crouse-Hinds inset
light). The remaining unit (bottom left) is
designed for taxiway lighting on curves has been
modelled on Idman.
The double-ended rotating beacon (left upper
center) marked many airports for many years but
has been superseded by a variety of forms
(patterned after ADB form, right upper center).
The illustrations partly represent those forms.
Some makers have produced a beacon that revolves
and has a nearly square shape. This has
approved by ICAO. Both ICAO and FAA approve of
a lower intensity beacon (left center) that has
two or more light units in a single apparatus.
One U.S. maker (Crouse-Hinds, top left) has
produced a beacon bearing a visual resemblence
to an alarm clock and one has produced a
somewhat more conventional design for higher
intensity needs in the U.S.
Obstruction lighting for many years centered
on two forms of beacons: the code beacon (bottom
right) and the small fixed incandescent light
(bottom center). Both forms continue in use and
are found in many nations. The illustration of
the simple, fixed light is a double unit. Other
forms have been added. Some of these are strobe
lights and have found nearly universal usage.
They include both high intensity (right center)
and medium intensity (lower center) forms.
Europeans have been especially inventive with
79
obstruction lighting; many of these involve neon
tubing. A common form is elongated with
spherical tubing (left of lower left center,
ADB) and one form (bottom left) is directly tied
to overhead power lines. An egg-shaped form has
been included because of its distinctive shape
(left lower center, Cegelec). It can include
either incadenscent or flourescent energy
source. Forms not pictured included a medium
intensity unit that displays circular neon tubes
and a cylindrical form with  linear neon tubes.
One manufacturer has created a medium intensity
strobe unit (EG) containing both red and white
lights.
Many older elevated lights were either
cylindrical (top left, from Westinghouse a
former major aids maker) or a more complex shape
centering on a Fresnel lens. More and more
variant forms are in use and many display some
form of dome. The illustrations include the
formerly widely employed high intensity light
unit. This continues in use in some systems
(according to Crouse-Hinds) and some makers (for
example Crouse-Hinds and Thorn Europhane)
continue to make it. The short cylinder form is
more common for high intensity use now (top
right, Godfrey Engineering). Some forms are a
true cylinder (for example, ADB) though the one
illustrated has a curved top. Others are closer
to a dome form. Some makers offer separate
fixtures for low/medium intensity use though
others have a single elevated fixture that
contains various options in color filters and
light source wattages.
The center rows displays three more
contemporary designs for medium intensity. They
include a true dome (left lower center, Tesla)
80
two variant domes (left upper center, Idman;
right upper center, ADB) and one that hestiates
between dome and cylinder forms (right lower
center, Cegelec). A variation of (dark image)
is high intensity. Cegelic uses dome designs
for all forms of elevated lights. The bottom
light is a taxiway holding position or stopway
light Crouse-Hinds). A second form bears a
strong resemblance to a standard traffic signal
(ADE) .
Approach light units may be similar in
appearance whether halogen or PAR forms. None-
theless, a representation of each form (left
top, EG, right top, Cegelec) is included.
Simple approach light systems utilize omni-
directional fixtures. Some of these are elon-
gated cylinders while others display shorter,
more squat cylinders; the form included is of
the former type (left upper center, ADB).
Flashing lights are either omnidirectional or
unidirection; (upper center, Multi-Electric,
right upper center, Godfrey). The unidirec-
tional model clearly displays both light and
strobe unit. Other forms can have variant
forms.
Final approach indicators picture include
(front view only) VASI (left lower center,
stylized graphic representation), PAPI (left
lower center), PLASI (right lower center,
partially stylized representation and one
three-color form (left bottom stylized
representation based on Danaid). T-VASIS is
similar in frontal appearance to that of VASIS
and is not included. Because light units are
inside the housings these representations
portray less of the aid than is true of most
other aid representations.
81
Signs, Markings, and Markers represents a
large and diverse field. Markings can become
meaningless when viewed in small segments.
Therefore markings are omitted from the pictures
but they are represented in their larger context
of an airport operation in Chapter 36.
Signs represent three major categories.
Mandatory instruction signs are represented by a
No Entry sign. Information signs are
represented by a VOR check point sign in two
forms: light letters on a dark background for a
day-use sign and black letters on a letter
background for an illumination version. The
aerodrome identification sign is obviously not
according to scale since the letters need to be
at least 3 meters high (107 inches).
Obstruction markings are represented by both
larger and smaller objects. Taxiway edge
markers are represented by a elongated marker; a
second form consisting of a cylinder on short
mast is found in Part B. The triangular shaped
object in lower left hand corner serves both as
unpaved runway edge and boundary markers.
The upper right hand corner contains a
typical wind come with illumination. A landing
direction indicator is found in the left lower
center position. To the right of that is a wind
tee. This is not found in ICAO and is no longer
standard in FAA but they continue in use and
various manufacturers continue to offer them.
ICAO was the source of most of these
illustrations. FAA supplied wind cone and wind
tee. And the taxiway edge marker was influenced
by ADB.
82
Electronic aids are less significant in a
visual mode but they are to a muted degree
present in that perspective. The left images
are of a VOR, Glide Slope and Marker Beacon/
Compass Locator facilities within ILS. The
center and right representations are of one form
of localizer, glide slope and marker beacon
facilities within MLS. Tull Aviation
substantially influenced the MLS images.
83
CHAPTER THIRTY-FIVE
LIGHTED AERONAUTICAL NAVIGATION AIDS
35A Approach Lights
35A1 Introduction
Pre-landing lighted aero aids include two
forms: approach lights and final approach
indicators. They can be studied as separate
entities though they are obviously related.
This subchapter focusses on approach lights
while 35B takes up final approach indicators.
The character of many aero lights (fixed or
flashing, color, intensity, direction of beam)
substantially defines many aero aids. The
configuration is important though it often
completes what was established by the character
of the light. For example, runway edge lights
display a specific pattern but the color and
other factors shape that configuration.
Approach lighting seems to reverse the
process: the complex and diverse configurations
themselves substantially establish the
environment of these aids. The colors are
important but they almost appear subsumed into
patterns; patterns which are beyond simple and
unvarying rows of lights.
The following segment will take up the
equipment for these aids. Messages, including
configurations, occupy a second section.
ICAO publications are vital to this
discussion though they do not give substantial
information on the equipment. Operational
85
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Simple Approach Category 11 / 111 inner 300m


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01 011 o9 0 9 of  4  0 0 41 4 4
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41 4 o 4 09 4  o] o]  0
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standards (including those of NATO, and the U.S.
FAA), manufacturer literature, and other
sources provide vital supplements.
35A2 Approach Light Equipment
Approach light systems have many components.
The components can be reduced to a elementary
bifurcation: fixed lights and flashing lights.
Fixed lights, for ICAO, have in turn two major
divisions: high intensity lamp units employing
standard PAR lamps or halogen lamps, and lower
powered omnidirectional light units  for simple
approach systems. Halogen cycle lamps is the
general name for a lamp family known by many
names including quartz, quartz-iodine or
tungsten-halogen lamps. They are incandescent
lamps using iodine or bromine as a fill gas.
They render colors well, and provide a high
intensity of light from a limited source. PAR
lamps or parabolic aluminized reflector lamps
are in two segments: the reflector is molded and
coated with aluminum. The lens is also molded
and imprinted with the desired pattern. The
filament is precisely positioned into the lamp
so it is at the central point. The lens is then
welded onto the reflector base (Lindsey 1991,
43, 41).  Some systems, including that of the
U.S., have a medium intensity unidirectional
approach system instead of the omnidirectional
simplified system of ICAO (FAA 1974, Chs 1-7).
Flashing lights (capacitor discharge; older
sources frequently speak of condenser discharge)
are of a single type performing a variety of
functions.
The principal light unit is a unidirectional
light displaying a Halogen or PAR 56 lamp. Some
systems with unidirectional medium intensity
87
systems may employ a PAR 38. The housing is
quite likely to be aluminum with stainless steel
hardware. Necessary color filters are also part
of the unit. The support for this light can be
of several forms: a short coupling with base
plate; a section of conduit; or a frangible mast
possibly set on a multi-dimensional framework.
Some approach lights are of the inset form.
These are similar to other inset lights; color
conforms to that of approach lighting.
There can be several intensity levels for
approach lighting. There are levels both for
daylight and night operations since approach
lighting is a fully-lighted aero navigation aid.
FAA also has abbreviated forms of approach
lighting for better visibility conditions. The
short form exists for high intensity (Category
II/III versions). ADB includes mention of
abbreviated forms though seemingly ICAO does
not. ICAO (Attachment A, ICAO 1990) includes
intensities but in more general terms than other
sources (FAA 1974, 16).
The second principal form of approach
lighting is that of the capacitor discharge
light. This light can have one several
functions. The most common type uses a PAR 56
discharge light within a housing similar to that
employed by other PAR 56 lamps. The lamp unit
is accompanied by a supply cabinet containing
controls, timer, flasher trigger, and power
supply. There are both both omni- and
unidirectional forms. There is also an inset
form of the discharge lamp.
There are other uses of flashing lamps
though they are more commonly associated with
FAA than ICAO. Lead-in Lights are listed  in
88
ICAO but the information in the Aerodrome Manual
is a reprint of U.S. (ICAO 1983, 4-65/66). This
light is employed where there is an uncertain or
hazardous route to the airport. The lights may
follow a curved, straight or irregular route.
The flashing light in question is a capacitor
discharge light.
ICAO speaks of a Runway Threshold Identi-
fication Light (RTIL) which is also flashing.
These are identical with Runway End Identi-
fication Light (REIL) though the later is
associated with approach lighting rather than
runway lighting (FAA 1974, 3-4). Some REIL
units are omni-directional. Omni-directional
lights make up one form of approach lighting
system under that name. Some REILs are also
omnidirectional. ICAO seemingly does not employ
omnidirectional flashing lights except for
obstacle lighting. Flashing lights are
frequently are attached to the supply cabinet
which is, in turn, attached to a base plate by a
coupling (See Multi-Electric, Godfrey, ADB 
other manufacturers).
35A3 Messages for Approach Lights
From one vantage point messages are
extremely simple for approach lighting: they are
either red (where side rows exist) and white
lights (centerline) are flashing or steady
burning (red are all steady burning). The
simplicity  ends there as well. Configurations,
levels of aviation  operations, variable
intensity levels combine to create a complex
situation. But a complex situation that upon
examination reveals clearly established patterns
(ICAO 1990, 48-51, TIRSPS).
89
Category II and III are in effect a single
level of operation; Category I is a simpler
level. Category I approach lighting is 900m in
length. The length is divided into three equal
segments of 300m. At the end of the first third
a crossbar runs across the extended centerline
of lights (if individual light units instead of
barrettes or light bars are employed there are
other crossbars at 150, 450, 600 and 750m). The
crossbar is 30m in length with the lights 1-4m
apart. The centerline lights are 30 m apart and
are fixed in character with variable white
color. One light per group for inner 300m, two
in middle 300m and three for outer 300m. If
barrettes are used instead they are accompanied
by flashing lights for all three segments. The
barrettes are 4m in length.
Category II/Category III configuration is
also 900m in length. There are crossbars at
150m and 300m from the threshold. Barrettes are
employed for the inner 300m; barrettes appear to
be first choice for middle and outer 300m
segments though two-light and three-light
patterns are acceptable as an substitute.
Flashing lights accompany middle and outer
barrettes. There are obviously many points of
similarities with Category The most notable
difference is the existence of a row of fixed
red lights flanking the innermost 270m of
centerline lights. The rows are comprised of
barrettes.
The simple approach light system is 420m in
length. There is a crossbar 300m from the
threshold which is either 18m or 30m in length.
Spacing of centerline lights is 60m. Either
individual lights or barrettes may be employed.
The lights are fixed and of a color that can be
90
distinguished from other nearby lights.
Sequenced flashing lights can be added for the
outer part.
Flashing messages for sequenced flashing
lights for ICAO are 120 flashes per minute; FAA
and some manufacturers have flash rates from
60-120 per minute (FAA 1974, 16-17). ICAO does
not mention intensity levels for flashing lights
though ADB  and U.S. sources do. Flash
intensities can be a single level or three
levels. Multiple levels are required if
flashing lights are to be employed during times
of greater visibility. The color is that of a
"xenon discharge lamp" ( FAA  1981, 4) which is
within the range of color known as variable
white. This color is termed "aviation variable
white by ICAO  and "variable-source white by U.S.
Standards, Breckinridge 1967, 48).
91
35B Final Approach Indicators
35B1 Introduction
With other forms of aero aids a single form
of light can sometimes be used to perform a
variety of functions (various runway and taxiway
lights provide examples of shared fixtures for
multiple purposes). Final approach lights
represent the reverse situation: a single
function is performed by a wide assortment of
lights. This requires a complex explanation
situation both for the historical development of
these aids and for the present aids. A vignette
of their history is found in Chapter 33B; this
coverage focusses on equipment and messages.
Clark Gordon (1981) and Clark Antonenko
(1993) have written important essays on final
approach indicators.
Messages will  be considered first since more
sense can be made of the diverse apparatus after
some understanding of purpose and messages is
achieved. There are so many different versions
of these indicators that an attempt at a master
listing has been compiled. This is found in the
Variant Classification: current forms in the
actual classification and past forms in the
explanatory notes.
The purpose of these indicators (whose
titles often include combinations of certain key
words: slope, path, descent, indicator) is to
provide descent information for an airplane
approaching a runway. The many kinds of
indicators have a core element in common: they
denote whether the angle of approach is on
course or too high or too low. They may also
92
distinguish between very low and slightly low
and between very high and slightly high.
3582 Messages for Final Approach Indicators
This coverage of messages for final approach
indicators has two dimensions: a review of the
range of signal coding forms, and the actual
messsage configurations of the indicators.
Clark and Gordon (1981, 5-6) provides a
comprehensive over review of signal coding.
Signal coding can be initially divided into
primary and secondary coding. Primary coding is
the most important, and may possibly be the only
form of coding. Secondary coding, when present,
supplements or augments the primary coding.
There are as many as eight forms of coding
in current use; variant forms may also be
employed. The various codings may be primary in
some instances and secondary in others. This
coverage has been greatly influenced by Gordon
and Clark (1981). These include "directional
shielding" though that term does not appear to
fully describe a coding situation in which the
message is partly lighted and partly dark (such
as a harbor light) or wherein the light is seen
only if the pilot and aircraft are in a specific
location in relation to the indicator (for
example, T-VASIS).
A second form is intensity coding in which
various directions have correspondingly
different intensities of light. These include
T-VASIS (TVG in Australia but renamed T-VASIS by
ICAO) and one type of Red/White VASIS employed
that approach. Flash coding is a third form
(PUSincorporates flashes or pulses though
color is also present). Pattern coding, a
93
fourth form, is associated with shape and symbol
as one form (T-VASIS noted for use of pattern).
A fifth form is that of position coding which
Clark and Gordon see as part of Pattern coding.
Alignment coding, the sixth form, is primary
coding for several older forms (Slopeline, MDLA,
FLULS, PVG, Glissada) and presumably pertains to
Alignment of Elements mentioned in U.S. sources
Slopeline described as a guide path by SNL (New
Lighted Guide Path 1948, 371); does that
constitute a looser definition of the term or
was Slopeline considered to manifest features
beyond a modern definition of guide path
indicators?. Little information is available
for movement coding, the seventh form. Finally,
color coding, the eighth form, is quite commonly
employed (R/W VASIS, PAPI and others).
There are five major forms of messages for
final approach indicators in current use (though
variant forms may also be employed): VAST,
T-VASIS, PAPI, PLASI, and Tri-Color. VASI, the
long-enduring standard indicator, is to be
phased out relatively soon. The colors for VASI
messages are white, white/red and red.
Three-Bar VAST, a variant form, a separate
explanation. Color coding is primary for VAST.
An all-white message denotes that the
aircraft is above the approach slope. Red/white
denotes the aircraft is on the approach slope;
red only indicates aircraft is below the desired
level. A transitional zone of pink can exist on
the margins of the red and white sectors. The
lights for VASIS are fixed in character for day
and night operation.
VAST in ICAO parlance is a 12 light system.
The 12 lights are arranged in groups of four
94
units with three lights in each unit. The upper
units are termed upwind bars while the lower
units are downwind bars. The wingbars flank the
runway with the downwind bars 150m from the
threshold and the upwind bars 210m beyond the
downwind units.
AVASI (or abbreviated VASIS) has four forms:
two groups of two lights flanking each side of
the runway; two groups of three lights flanking
the left side of the runway only; two groups of
two lights on the left side; and two groups of a
single light unit on the left side. The message
configurations follows the pattern of VAST
though with fewer lights.
3-Bar VAST is comprised of a VASI
configuration plus a two-light unit on each side
of the runway. The additional units are termed
upwind bars and the upwind bars of VASI becomes
the middle bars. Because of the additional bar
there are two possible glideslope approaches.
If the approach is to be between the downwind
and middle bars the correct approach is denoted
by white indications from the downwind bars and
red from middle bars and upwind bars. If above
the glideslope the indication is red from upwind
bars and white from downwind and middle bars.
If really above the glideslope all bars show
white. If below then the indication is red from
all the bars.
For an approach between middle and upwind
bars the desired approach is marked by white
lights from downwind and middle bars and red by
the upwind bar. An all white indication denotes
the aircraft above glideslope; a below-
glideslope position is marked by a white
indication from the downwind bar, and red by
95
middle and upwind bars. An aircraft far below
the glideslope receives an all red message.
Spatial configurations are those of VAST with
the additional bar 210m above the middle bar.
T-VASIS utilizes pattern as primary coding
with color in a secondary role. T-VASIS is
comprised of twenty light units flanking the
sides of the runway. There are two wing bars
with four light units each located at
approximately the midpoint of the runway and
perpendicular to it. The wing bars are 280m
from the threshold. Parallel to the runway are
three single light units above the wing bars and
three below. The single units are 90m apart
with those lights nearest the wing bars 45m
above and 45m below the wing bar. The lower
parallel lights are termed "fly-up units" and
the upper are called "fly-down units." There
are variant versions of T-VASIS: AT-VASIS, and
RT-VASIS. AT-VASIS (Abbreviated T-VASIS) has ten
light units. RT-VASIS or (Reduced T-VASIS) has
just six units.
Clark and Antonenka provide a clearer visual
explanation of T-VASIS than does ICAO. If a
pilot is above the approach slope point the
lights will appear as an inverted "T" which is
akin to a directional arrow on a road. The "T"
indicates the pilot should fly-down. The "T"
may show a tail with three lights, two lights or
a single light depending how far the pilot is
above the approach point. If the pilot is below
the approach point the an upright "T" is
displayed indicating fly-up. Again, the "T" can
have a tail of one, two, or three lights. If a
pilot is far below the desired altitude a "T" in
red is formed termed "gross undershoot signal"
which denotes danger.
96
The VASIS system displays color indications
at all times but T-VASIS shows only a portion of
the lights at anytime; the remaining lights are
not visible except at a specific position. The
pattern formed by light (or lack of light)
constitutes the message. VASIS indicates
whether on, above, or below course. 3-Bar VASI
indicates on, above, quite above, or below in
one matrix and on, above, below or quite below
in the other. T-VASIS indicates three levels of
above and three of below as well as on; it also
has a far below course indication. T-VASIS has
seven indications versus three or four possible
messages in conventional VASIS.
PAPI has just one unit: a four-light wing
bar on the left side of the runway; APAPI  has
just two lights. Color represents primary
coding for PAPI and APAPI.  There are five
possible messages: when on approach the two
lights nearest the runway are red and the two
farthest from the runway are white. If above
the approach slope there is one red light
(nearest the runway) and three white. If well
above the approach slope all the lights are
white. Three red lights nearest the runway
denote a below the approach slope position.
Four lights indicate well below the approach
slope. APAPI indicates on approach with one red
nearest the runway and one white light away from
the runway. An above the approach slope
indication consists of two white lights, and
below the approach slope is marked by two red
lights. H-PAPI is a variant form for helicopter
operations. PAPI units can vary in size and in
number of lamps. Most are two or three lamp
units though Idman has a four lamp unit. Lamp
wattage is frequently 200w  though some 45w  and
100w  lamps are available. Thorn Europhane
97
produces a small unit termed a Mini-PAPI (PAPI:
What the ... 1984, 35).
There are several other approach slope
indicator systems in use that are not mentioned
in ICAO publications. These include Tri-color
systems and Alignment of Elements systems.
Tri-color systems (seemingly they lack the
usual acronym) is a one light unit operation.
Below approach slope is denoted by red, above
approach slope is marked by amber. If on
approach slope a green light is displayed.
These units date back to the 1930s and are
represented by at least two current models: the
Glide Path Indicator (GPI) of Cegelec and T-PASI
(Tactical Portable Approach Slope Indicator) of
DANAID).
Pulsating systems (usually PLASI or Pulse
Light Approach Slope Indicator) also has one
light unit. This is  a two-color approach based
on pulse and color coding. The below approach
slope indicator is marked by pulsating (or
flashing) red. Above approach slope is noted by
pulsating or flashing white; on approach
indicator is steady white. One form is approved
by ICAO for helicopters but the principal form
is not. AIP 1990, 0-3; Devore Aviation 1991).
The Alignment of Elements systems (AOE) is
either a day-only or a partially lighted system.
It consists of plywood panels painted either
flourescent orange or black and white. Lights
may be included for night-time use. There are
three panels. When above glide path the middle
panel is above the side panels. When below
approach slope the middle panel is below the
side panels. On glide slope is marked by the
98
three panels in a straight line. The panels are
usually found on the left side of the runway
(AIP 1990, 0-3).
35B3 Final Approach Indicator Equipment
VAST units are installed in a metal housing
mounted on short legs. The lamp units are two
PAR 64 lamps behind a white and red spreader
lens; the lens is quite elongated on a
horizontal plane. The lamps are mounted in the
rear of the unit and the lens is mounted over a
narrow slit aperture in the front of the box.
VASI units lack the precision optical projectors
of PAPI (Multi-Electric 1978). The ICAO
Aerodrome Design Manual includes a second form
of VASI that is a projection type and suggests
the PAPI system.
The PAPI system is also contained within a
metal housing. The unit is smaller than a VASI
unit (about half the size of VASI units though
one manufacturer claims their PAPI is one-fourth
of their formerly produced VASI units). The
unit contains either two or four lamps. The
lamp assemblies contain reflector, lamp holder,
and quartz lamp. The assembly is mounted in the
rear of the box. Beyond the assembly is a red
filter, inner lens, outer lens and front glass.
It is mounted on three or four legs. The unit
is of a precision optical design that presents
narrowly focussed and precise light beams.
APAPI units are of two lamp design. A full
installation has four units with two lamps each;
some models though have three lamps per unit
(see, for example Danaid 1991, 2-3 Mk.10).
According to the ICAO Aerodrome Design
Manual presents two types of T-VASIS light units
(ICAO 1983, 4-74, 4-75, 4-80, 4-81
99
TISRPS). The first is termed the blade type. It
consists of one basic assembly with three
variations. The first variation is the fly-down
unit. The light unit, which is located in the
rear of the unit, displays a beam that is
channeled by a blade above and below the
projected light beam. This unit is a white-only
version. The wing bar variant adds a red filter
in the front of the unit with a blade at the top
edge of the light beam. The fly-up unit has a
blade below the light beam. There is a red
filter above the light beam and in front a blade
beneath the beam. The aperture for that unit is
quite narrow permitting only a narrow beam of
white light and a narrower band of red.
The second form of T-VASIS is of the
projection type. The housing contains a lamp
assembly containing lamp, filters and projection
lens. This unit is similar to one type of VAST
system and also suggests features of PAPI.
Only limited information is available on the
Tri-color System. It is comprised of one light
unit that projects a three-color message. One
form, that of T-PASI, is comprised of the
housing, halogen lamp, three-color filter,
reflector and lens (Danaid 1991).
The PLASI  system consists of a single box of
somewhat squat yet elongated design on flexible
legs. The lamp assembly consists of condenser
lens, halogen lamp, lamp holder and red filter.
A mechanical device operates the shutter that
creates the pulses (Devore Aviation). A variant
form of PLASI is the Optical Localizer which
projects a horizontal beam rather than a
vertical one but the equipment is similar to
that of PLASI.  This is also a Devore product.
100
35C Runway Taxiway Lights Messages
35C1 Background, Terminology Functions
Airport lighting began very simply: boundary
lighting encompassing the perimeter of the
landing field accompanied by necessary beacons
and obstacle lights. Airport lighting has since
blossomed forth with many forms of lights. A
first glance at airport lighting can seem
bewildering since the many lights are of diverse
forms with a broad range of messages displayed in
contrasting patterns. A further examination, to
be begun in 35C2, will illustrate the essentially
simple, albeit multi-layered, character of aero
aid equipment and messages.
Runway and taxiway area lights can be divided
into three segments: Landing aid lights, runway
edge lights, and taxiway lights. Landing aid
lights include touchdown zone lights and center-
line lights. Runway edge lights include not only
lights by that name but also runway end/threshold
lights (those lights that mark the bottom and top
edges of the runway). Taxiway lights include
center, edge, exit, intersection models as well
as clearance, holding position and stop bar
forms.
Runway and taxiway lights are in two forms:
elevated and inset (the latter are sometimes
referred to as semiflush or inpavement lights).
Some lights are either exclusively inset or
elevated while others may appear in both forms.
The physical dimension (inpavement and elevated)
will determine the format of the following
coverage with elevated lights in 35C2 and
inpavement in 35C3.
101
Runway and taxiway lights are not in
continuously operation and therefore lack a day
dimension. That fact requires signs and markings
to be in close proximity to the lights in order
to supply day aids. Signs and markings are
considered in Chapter 36.
Parking and Docking systems are included in
this subchapter. Parking lights are inset
taxiway lights while docking lights are a
multifaceted system employing alphanumeric,
graphic and signal lights mounted well above the
pavement areas. But they remain closely
integrated with runway and taxiway forms and are
thereby included here.
ICAO publications are of primary importance
in this study but other standards and
manufacturing trade literature are incorporated
into the coverage. The use of multiple sources
may lead to confusion since the sources project
disparity in styles and contents. This concern
is tempered by the introductory nature of the
monograph which may not fully capture either the
source material or the problems lurking therein.
35C2 Inset Lights
A division of airport lights can be made
according to physical fixture or according to
purpose. It may appear more sensible to divide
according to purpose (taxiway in one group,
runway in another). This compiler has divided
according to the less likely principle: fixture.
Why? because of the close resemblance between the
physical part of the lights. Any other dividing
splits very similar equipment and unites very
dissimilar units. The message coverage is the
better place to unite lights according to
102
0
O  00
0
0
0

0
0
CC7
000  0 0 00000
0
0
0
0
0
0
0
0
0                 
0
0
0
0
0
0
0
0            
Figure 2.     
LEGEND   0  0 0 17  0 0
Clear Circle. a  Runway Liyhte
Solid Circles Green Lights fol.  than cx,way boundaries)
Solid Circles Blue Lights )outside taxiway bOundarie81
Solid Circles - Alternating  Green  i Tellox Lights )denoted by  arro,
Stop Bar Unidirectional ISBU) - Red Lights
Stop Bar Omnidirectional !SRO) - Red lights
Clearance Bar UnidireCtiOnal ) COO) Yellow
Runway
Threshold Green
TD 2 White (2-Light barrette units)
Edge - white
Centerline Threshold to 900m from end:  WM.,
902m co 200 m from end: Alternating White c Red
302m to end: Red
(This con Figuration represents a basic patter, alternate mode, may be in use:
Runway Taxiway Lighting
103
function; for example, taxiway lights together
and runway lights together.
There are three major forms of airport inset
lights: runway, taxiway and approach. While most
approach forms are outside the paved areas of an
airport there are some inset approach lights in
use. Inset approach lights are included in the
subchapter on approach lights rather than in this
segment.
Taxiway lights have a single purpose while
runway lights encompass several functions as
outlined above. Nonetheless, taxiway lights have
variant forms: straight sections, curved
sections, intersections, and exits. ICAO
standards may be more general, less precise than
national standards practices with the result that
taxiway lights are not a narrowly designed
subject though degree of commonality is present.
The physical apparatus of inset lights varies
somewhat according to purpose and manufacturer.
Nonetheless, some gneral comments can be made
about the varieties of inset lights. Since the
lights are often run over by aircraft they
require a strong housing. This housing is often
of cast iron which may be plated with cadmium; a
nickel-molybdenum alloy may be substituted (users
included ADB). Graphic iron is employed by
CEGELEC, Omnipol/Tesla employ aluminum alloys;
Omnipol/Tesla also uses cast steel. The assembly
frequently consists of an outer cover that
contains openings for the lens; the lens may be
an integral part of the cover. The upper cover
is bolted to the lower with a gasket between them
to prevent leaks. The lower cover contains
optical and lamp assemblies. Lights are fre-
quently quartz halogen. Some outer covers may be
set within a metal ring of equal strength. Some
104
taxiway lights are wide beam while others are
narrow beam. Crouse-Hinds speaks of some ICAO
taxiway lights as having assymmetrical beams
though seemingly ICAO does not mention that form;
Philips (now Thorn Europhane) also offers an
assymetrical form. References for this coverage
include Omnipol/Tesla, Crouse-Hinds, Cegelec,
Idman, Thorn Europhane, and Light Repairs 1989,
34) .
The upper covers of taxiway light forms
contain a lamp cartridge that can be removed from
the surface without removal of the entire unit; a
removable metal plate protects the cartridge from
damage. Inset lights can be bidirectional, uni-
directional or omni- directional. The last-
named may have a domed shaped lens protected by a
upward extension of the cover and buttressed by
ribs radiating out from the lens. Some forms of
inset lights have double lens for each direction;
the double lens may be sent into separate window
channels.
35C3 Elevated Lights
Elevated lights are more common than inset
lights. All airports with lights contain
elevated forms though not all have inset lights;
for example, what are termed general aviation
(non-commercial flights) may have only basic
elevated forms). Elevated lights can obviously
mean approach lights as well as runway and
taxiway forms. Though frequently the term
"elevated" refers only to runway and taxiway
forms. This may stem from the fact that nearly
all approach lights are elevated (with only a few
inset forms) and no differentiation is required;
lights within paved areas can be numerous in both
styles and differentiation is necessary.
105
In addition, elevated runway and taxiway
lights have the configuration of a fully-
integrated unit including the support; approach
lights and their supports are often separate
units requiring two manufacturers. Therefore,
elevated lights, unless otherwise noted, refer to
runway and taxiway lights in this study.
The high intensity runway edge light requires
a fixture exclusively for its use but all other
elevated lights can conceivably share a single
fixture though this is not always be the case.
This can mean that low and medium elevated runway
lights for edges of runways, threshold/ends and
taxiways may all use the same fixture with
necessary changes in lenses and filters. Some
manufacturers market a fixture usable only for
low intensity edge lighting; one example of this
practice is Godfrey (Godfrey ud GEA05). While
others follow the multiple-use pattern with one
fixture; for example Crouse-Hands, ADB. and the
former Philips concern (Crouse-Hinds 1990, BT-1.3
others: ADB, A.03.150e, Pollock 1990).
An elevated light of wider beam can be
employed at thresholds where no approach lighting
is available and that fixture is separate from
the basic elevated fixture. The holding position
light for taxi operations is an elevated fixture
of markedly different appearance. It can be a
horizontal fixture of two lights on double pipe
supports or a two-light vertical fixture visually
similar to a traffic beacon. Principal
components of elevated lights include lens, lamp
assembly, stem, hardware and foundation. Lenses
frequently consist of an outer and inner lens
(the former is at times referred to as an "outer
globe"). The support for the lens unit is known
by several terms: conduit post, stem, tube or
column. The lamp is frequently quartz or quartz
106
halogen; some incandescent bulbs are in use as
well. Hardware is frequently stainless steel
while much of the remaining unit is alumninum.
Couplings are frangible since this is an above
ground unit. Plastic is sometimes employed for
the upper housing. The unit can be affixed to
several forms of foundation; stake and base plate
are the most common. References include an
amalgam of manufacturers; many have been
previously described.
35C4 Messages for Elevated Inset Lights
Messages for aero navigation aids can be a
complex and technical matter. The following
account is only a summary and should not be
employed for actual air navigation. Runway edge
lights display fixed (also termed steady burning;
ICAO favors fixed while FAA prefers steady
burning) lights in variable white. The con-
figuration is comprised of two parallel rows with
60m spacing on instrument runways and 100m spac-
ing on non instrument runways. Displaced runways
can be marked with red lights to the point where
the runway begins. The last portion of the
remote end can be denoted with yellow lights.
Runway Threshold Identification Lights
(termed Runway End Indentification Lights or REIL
for FAA use and associated with approach
lighting; FAA 1974, 63-64). These lights display
flashing white lights with a flash rate of 60-120
per minute. They are unidirectional and found
near the outer corners of the approach end of the
runway. They are two in number and located at
noninstrument runways. They are apparently an
inset light for ICAO though an above ground unit
with lamp and housing for FAA usage.
107
Runway Threshold Lights are perpendicular to
the threshold. They are fixed unidirectional
lights displaying green in the approach
direction. Noninstrument and nonprecision
runways are marked by six such lights. ICAO
provides a formula for spacing lights at Category
I, and Catories II and III rather than giving an
exact number of lights. Wing Bars (found in ICAO
int absent from some national systems including
the FAA) are groups of lights found at some
runways where special attention to the runway is
required. They consist of two wing bars or
groups with at lest five lights in each. They
are fixed, unidirectional and green as are
standard threshold lights.
Runway End Lights are perpendicular (or at
right angles) to the runway end. There are at
least six lights equally spaced (or in groups
that are spaced symmetrically. The lights are
unidirectional and red in color.
Runway Center Line Lights are employed with
Category II and Category III operations. They
are fixed and display variable white lights from
threshold to 900m from runway end. The lights
are alternating red and white from 900m down to
300m and solid red for the last 300m.
Runway  Touchdown Zone (TDZ) Lights are also
employed with Category II and Category situ-
ations. The lights encompass the first 900m of
the runway and are in two rows of lights flanking
the centerline. TDZ lights are in groups (or
barrettes) of three lights. The messages are
fixed, unidirectional and in variable white.
Only inpavement lights are employed.
Stopway Lights follow the edges of the
stopway and are "coincident with the rows of the
108
runway edge lights" (ICAO 1990, 73). They are
fixed, unidirectional and red in color.
Taxiway Center Line Lights are not assigned
to specific levels of aviation (precision, non-
precision, categories) but general guideline
exists: if traffic volume is not substantial then
edge lights and markings are sufficient. The
lights are fixed and green, of the inset form and
bidirectional. Green and yellow lights employed
at exits according to established formulas.
Lights for straight sections are a maximum of 30m
apart; there are various special situations and
exceptions to that rule. Lights on curved sec-
tions can be as little as 7.5m apart. Rapid exit
lights are a maximum of 15m apart with various
exceptions. Other exits are at most 7.5m apart.
Taxiway Edge Lights are fixed and blue in
character. They are also found at holding bays
and apron edges. These constitute the basic
level of taxiway lighting.
Stop Bars are located at taxi-holding
positions according to set formulas. They are 3m
apart and extend across the width of the taxiway.
They display red lights and manifest a fixed and
unidirectional character. The message is one of
stop-and-go.
Clearance Bars define holding limits in
situations where stop-and-go indications are not
required. They display fixed, unidirectional
messages in yellow and spaced 1.5m apart.
Visual Parking Docking Guidance systems are
required when aircraft need to be precisely
positioned. Terminals without aerobridges employ
a system of markings and lights. This approach
is termed Aircraft Stand Manoeuvring Guidance
109
Lights. This system employs low intensity inset
taxiway lights with yellow filters. The second
system is termed a Visual Docking Guidance
System.
Visual Docking Guidance System (VDGS), is a
multifaceted aid that denotes the form  of
aircraft (positioning dependent on that data),
distance from docking perimeter and location in
relation to docking approach lane centerline.
One form displays information through numbers and
graphic symbols while a second form employs words
and graphic symbols. The first form displays red
numerals indicating one of 17 aircraft types (47
for a 747, 07 for 707, 10 for DC10, etc). It also
displays three pairs of signal lamps indicating
gate clear (green), caution/ 4.5m to dock, and
red for stop/at dock. Finally it displays three
vertical tubes of which the center is green and
the flanking tubes are yellow. When the aircraft
is on the centerline the green will  be visible;
if off center either the left yellow or right
yellow tube is visible (ICAO 1983, 4-123, 4-124,
4-125 TISRPS).
The second form is comprised of a single
message panel with multiple messages. It dis-
plays green lights at the bottom, a series of
adjoining lights for much of the length of the
panel with three colors: green lights for most of
the distance denoting closing distance to the
dock then amber lights indicating docking is near
and finally red lights indicating stop.
Alphanumeric messages at the top of the panel
indicate stop followed by either "OK" or "TOO
FAR"; the later indicate an overshoot. A narrow
vertical line of color indicates on centerline
(green) or move right or move left (both yellow).
110
The primary focus of aviation is on (Con-
ventional Takeoff Landing) forms but there are
other forms including Vertical takeoff and
landing (VTOL) (helicopters and tiltrotor craft)
and Short Takeoff and landing (STOL).
Heliports have three main elements: final
approach and takeoff area (FATO), takeoff and
landing area, and obstacle clearance zone. The
FATO can be a circle or rectangle and should be
at least as large as the rotor area. The second
element is a larger area that includes the FATO.
Aids include identification markings (white),
wind cone, and taxiway centerline markings
(yellow). The identification beacon displays
white-yellow and green messages. Perimeter
lighting (suggestive of older boundary lights)
are in yellow. Landing direction (approach)
lights are a row of yellow lights. Taxiway
lights are blue. Various final approach units
are available and are described with CTOL forms.
References include Ashford 1992, Ch 14; also FAA
1994, Paragraphs 31, 32).
Vertiports focus on tiltrotor craft but can
accomodate helicopeters; vertiports can be
elongated as well as square. In addition to a
FATO, Vertiports have a touchdown lift-off
surface (TLOF) and aids center on the later.
TLOF is marked by "V" shaped identification
marking with and white edge markings. Lights for
FATO limits are in blue while TLOF are in amber.
Taxiway lights are in blue. Identification
beacon is of the heliport pattern. Approach
lights can also be present. STOL aviation is
akin to CTOL though flying surfaces are more
truncated. Primary reference is Ashford 1992, Ch
14.
111
35D Beacons Obstacle Lights
35D1 Introduction
This may be a "marriage of convenience"
since beacons and obstacle (obstruction: FAA 
NATO; obstacle: ICAO) lights are two different
subjects. However, the study is brief and
separate subchapters would result in two very
short segments. Further, many obstruction
lights can be regarded as beacons; some
obstruction beacons and non-obstruction beacons
share the same equipment. Finally, placing
non-airport lighting together is not an unknown
practice; for example, AIM 1991 (Table of
Contents) places these forms together. Separate
segments for equipment will  be provided in this
subchapter though messages will  be together.
Some forms of airport lighting require precise
standards with great amounts of details;
examples are approach lights and final approach
indicators. But other forms of lights are much
less precise and the characteristics are minimal
and seemingly a variety of light forms will
suffice. This  will  prove true for beacon and
obstacle lights.
The term beacon in marine usage can include
all visual aids and at least some electronic
aids. Aero usage appears to restrict the term
to omnidirectional lights established well above
ground level; these lights are also in a
flashing mode. The traditional Fresnel beacon
employed for obstruction lighting is so regarded
by the FAA though seemingly not by ICAO (FAA
1991, 34). It may well be necessary, at least
for the sake of simplicity, to refer to all of
the lights in this segment as lights with a
112
subform of beacons for a restricted and
specified variety of above ground lighting.
Beacons have a relatively long and colorful
history. They are the only part of aero aids
that generates any of the interest accorded to
lighthouses though only to a muted degree. The
history segment of this chapter offers some
information on that subject. However, beacons
are a small and restricted topic in contemporary
aero aids and therefore coverage of that topic
is limited. That should not suggest a lack of
historic and contemporary importance.
Obstruction lighting is part of a larger
topic: marking and lighting of obstructions and
obstacles. It includes general principles on
the scope of obstacles; the denoting of
obstacles both at airports and away from
airports; the specifics of lighting equipment
and their messages; the specifics of markings
and their messages. Light equipment requires a
separate segment but since light messages are
brief they share a segment with beacon messages.
Unlighted obstruction aids will be presented in
the next chapter.
35D2 Beacon Lighting Equipment
For ICAO there are three beacon types:
aerodrome, heliport and identification beacon;
it may be more accurate to view the heliport
beacon as a variant form of the aerodrome
beacon. Standards for many forms of airport
lights are extensive but not for the beacon.
There are only a few statements regarding the
beacon with the result that wildly different
designs have resulted. For example, ADB and
Thorn Europhane have a beacon that is literally
113
a square box with lamp assemblies in four
directions (ADB  A.08 230e TISRP; Thorn
Europhane, 25). Crouse-Hinds has a two sided
form that looks very much like a giant alarm
clock (Crouse-Hinds 1992, CT-7.5) while Cegelec
has a more conventional design of four circular
lens mounted on a square housing (Cegelec).
ICAO simply states that the beacon must
flash and that it must follow certain intensity
and candela requirements. There are no
requirements beyond that. The beacon can
conceivably rotate or flash. AIM indicates that
a capacitor discharge lamp can be employed for
this purpose (AIM 1991, 2-1-7). The  ADB  and
Thorn Europhane version has two clear windows
(one in reserve) and two green windows (also one
in reserve). The housing is steel and contains
parabolic reflectors and displays lamps that are
"prefocussed mirrored dome lamps";  Crouse-Hinds
speaks of halide lamps.
The code beacon was a mainstay of aero
navigation aids for many years. The beacon is
all but identical to the Fresnel obstruction
beacon and was introduced in the 1930s. The
primary U.S. specification was written in 1942
CAA 1942). But in 1980 the FAA cancelled the
specification in favor of a new obstruction
lighting standard (FAA 1980). The code beacon
was a generic term that encompassed not only
hazard beacons but various forms of airport
identification beacons (CAA 1942). Despite the
cancellation AIP and AIM  continue to include the
code beacon (AIP  1990, AGA-05; AIM 1991, 2-2-1).
The code beacon, now known as an identification
beacon, has official standing with ICAO.
114
ICAO devotes less attention to the
identification beacon than to the aerodrome
beacon. The beacon is to flash, to show in all
directions, and should be visible up to a
minimum of 45 degrees above the horizon. The
ADB version of the beacon is that of the Fresnel
beacon and presumably other versions are akin to
it.
35D3 Obstruction Lighting Equipment
There are three levels of lights for
obstruction purposes: low, medium and high
intensity. There are several forms of low
intensity for ICAO (judging by the offerings of
selected manufacturers). Probably the most
common form made by a number of manufacturers,
especially in the U.S., is a simple fixed red
light. It consists of a glass cover, often
doubling as a lens or containing a lens,
surrounding a low wattage lamp, and lamp holder
assembly. This light is omnidirectional with
red lens; some versions may have a clear lens
and red filter. A double form of the light is
found in some nations including Canada and the
U .S.
A second version of this light, made by ADB,
is fixed and red and conforms to cd intensity
and omnidirectional character but has a far
different means of illumination. The light in
question is a "neon discharge lamp emitting a
red light." The light is a simple unit with the
discharge lamp, lampholder and housing. There
is no filter. One form of this light contains
only a limited number of spirals; a second has a
substantial number of spirals (ADB A.07.220e).
115
A third version, possibly only made by ADB,
is a curious entity termed a "Balisor lamp". It
consists of a cold cathode neon-filled lamp, is
of low intensity, and feeds off the electro-
static field from a high-voltage power line. It
is designed to illuminate power lines which
constitute a difficult obstruction to mark.
Cold cathodes refers to electrodes that heat to
about 200 centigrade; hot cathodes run
considerably higher (Laughton 1985, 27/17).
The historic centerpiece of obstruction
lights (more precisely beacon) as well as code
and identication beacons has been the double
barrel-shaped fresnel lens. It has been a
mainstay for over fifty years and it continues
to be manufactured in many areas of the world
including Asia (for example Toshiba), Europe
(ADB A.07.270e) and North America (Crouse-Hinds
1962, 301,1).
This beacon has an upper and lower lens
which are identical. A steel or aluminum hinges
both unites and divides the light. There is a
lampholder and lamp for both sections. There is
also a lower body or base and various gaskets,
rings, hinges. It is a flashing light that is
omnidirectional. Some versions are of clear
glass with filters while others are of red
glass. The flash unit is external to the
beacon. Some newer versions employ an
electronic flasher that reduces but does not
fully shut off the lamp thereby extending the
life of the lamp. The Fresnel beacon is of
medium intensity.
Developments in optics have led to the
capicitator discharge lamp (sometimes known as a
strobe light). This lamp can be of several
116
types and constructions as well as terminology;
the later is not always uniform. Some versions
of the lamp employ a linear flashtube while
others are helical (spiral) in shape. Flashing
lights for approach lighting systems are also of
this form. The flash is brought about by the
master timer actualizing the trigger relay and
thereby ionizing the xenon gas within the lamp.
This creates an arc resulting in a brief but
brilliant flash of light. The power supply or
controller contains the equipment for supplying
current, timer and other components (Multi-
Electric 1974, 2-3 to 2.6).
There are three versions of capacitator
discharge (cd) obstruction lights. The most
common is one employing a helical shaped lamp.
This is a medium intensity unit. It consists of
acrylic lens, lamp, lampholder, base and control
unit containing timer and other equipment. This
is an omnidirectional unit. The light is white
in most uses though a red version is seemingly
available. Some use is made of this form of
light in special marine situations. In fact the
light bears a markedly similar appearance to
standard river and harbor lights. It produces
20,000 cd during the day and 2,000 cd at night.
A variant form of the medium intensity cd
light employs lineal flash tubes. These are a
smaller version of those used in high intensity
units. This form requires three parabolic
mirrors, three flash lamps. The unit becomes
omnidirectional because of the three precisely
positioned lamp and reflector elements; it does
not revolve. This form, produced by EG. may
eclipse the Fresnel lens because the light can
be produced in a dual version displaying both
red and white colors in a single unit. The
117
light does not have a lens system. Both types
contain a outer plastic cover but that does not
constitute a lens. It produces about 20,000 cd
with 160w during the day and 2,000 cd with 30w
at night (EG 1992).
The first non-incandescent alternative to
traditional obstruction lighting was the high
intensity strobe light with quartz/xenon
flashtubes. The light resides in a simple metal
box with glass front. It provides a white light
that is unidirectional. The light can produced
200,000 cd and is designed primarily for
daylight use; reduced intensity or red lights
are employed at night. It produces 200000 cd
during the day; 20000 cd at twilight and 2000 cd
at night.
35D4 Beacon Obstruction Light Messages
Beacon messages are quite simple. Aerodrome
beacons display white or white/color messages
with 12-30 flashes per minute. A minimum of 20
flashes per minute is recommended. Land
aerodromes display white or white/green messages
while water aerodromes display white or white/
yellow messages. The flashes are to be visible
in all directions. This material is based on
ICAO standards.
Identification (code) beacons display green
messages at land aerodromes and yellow at water
aerodromes. Messages are to be visible in all
directions and visible well above the horizon.
Messages are international Morse code with six
to eight words per minute (Morse code symbols
are 0.15 to 0.2 seconds per character).
118
Low intensity obstruction messages are fixed
and red in color in all instances; low intensity
lights are to be at least 10cd. Medium
intensity lights are red and flashing with 20-60
flashes per minute. Medium intensity lights
when employed with high intensity lights are to
be white.
High intensity lights are always white.
Flashes are to be 40-60 per minute except for
lights on power transmission towers where they
are to be 60 flashes per minute. High intensity
lights, other than for towers, are to flash
simultaneously. Tower lights flash in a
sequential pattern beginning with the middle
light, continuing with the top light and ending
with the bottom light.
Lights for unserviceable areas (within
restricted use areas) can be a fixed red light
or a flashing red of yellow light (ICAO 1990,
94).
119
I
0
CHAPTER THIRTY-SIX
PARTIALLY-LIGHTED UNLIGHTED
AERONAUTICAL NAVIGATION AIDS
36A Signs Markings
36A1 Introduction to Chapter 36
It was a relative easy task to divide up
marine aids to navigation: lighted aids were
assigned to one chapter, daybeacons to another.
It was, of course, presupposed that lighted aids
were not fully lighted and that an integral day
dimension was present (a limited number of
marine aids now display strobe lights and that
somewhat alters the situation). The primary
sources for this segment are ICAO publications:
Annex 14, 1990, Volume I, Ch 5: 5.4 5.5, Chs 6
7; Volume II, Ch 5: 5.1 5.2, Ch 33).
The primary problem for marine aids was the
point of differentiation between what are termed
major lights and minor lights; all forms of
buoys were considered separately. Aero
navigation aids presents a more complex matter.
Aero lighted aids lack a integral day aspect in
most cases (obstruction marking can considered
to be an exception) and some lighted aids are
fully-lighted while others are a fully-lighted
aid but only during periods of operation and
thereby partially-lighted for the classi-
fication. As noted previously, partially-
lighted for aero aids has a different meaning
than it does for marine aids.
121
There is a second problem in dealing with
aero aids that are not fully-lighted (that is,
aids that are operational at all hours versus
aids lacking a day dimension but are not
operational at all hours): the problems of signs
which may or may not be lighted. Some forms
call for illumination, others may or may not be
lighted, and yet others are never lighted. And
the form of illumination can be an integral part
of the message or it can be a substitute for
natural light and thereby take on the form of
floodlights. Even in cases where the lighting
is internal and integral to the sign the place
of light is different than the place of light in
a lighted aid that lacks an alphanumeric or
other symbols. Why? because the light dimension
of a sign is not required for the sign to act as
a sign at least some of the time. But a light
aid does not exist in its message capacity
except when the light dimension is activated
(and a unit of light energy has no other
dimension while a lighted sign includes not only
light energy but also a symbol in some form).
There is seemingly no adequate response to
the problem of differentation of aero aids that
may or may not contain or accompany some measure
of illumination. The response of this study has
been to: 1) assembly all lights with a sub-
stantial lighted dimension together and then 2)
assembly essentially unlighted aids - including
some with a more limited lighted dimension - in
a separate grouping. All aero lights for this
study are located in Chapter 35 and all
unlighted and partially-lighted aids in this
chapter.
This chapter begins with signs (36A2) and
markings (36A3) and continues with indicators
122
(36B1), markers (36B2), obstruction markings
(36B3), and restricted use markings (36B).
36A2 Signs: Types Messages
Signs are comprised of two multi-member
categories: mandatory instruction and
information signs, and two single-member
categories: aerodrome identication and aircraft
stand identification signs.
Mandatory instruction signs consist of
prohibitions on movement messages (except when
authorization from the control tower is given).
ICAO includes three forms of these signs:
taxiway/runway intersection signs, category II/
III holding signs, and no entry signs. From the
accompanying descriptions of signs and messages
it may seem that a non-category II/III holding
position sign is also in use but that function
is subsumed within taxiway/runway sign forms.
Illumination can be provided if signs are needed
at night; that illumination can be either
internal or external. Both incandescent and
flourescent lamps can be employed as a lighting
source for internal illumination (Safe Signs
1989, 34 and Curved Signs 1989, 39).
These signs are rectangular (which is the
recommended shape of all ICAO sanctioned signs)
with a red background and white message forms
(termed inscriptions by ICAO). Taxiway/runway
intersection signs include runway designations
for one or both ends of the runway that
intersects with a taxiway. No entry signs
denote prohibitions that are definitive and that
preclude exceptions. The remaining holding
position signs are for Category II, Category III
or joint Category II/III operations.
123
Information signs include two general forms,
a catch-all form, and a specific form. General
forms encompass needs for information on
location or destination in regards to movement
activities. Signs "provid[ing] other
information" constitutes a catch-all category.
The specific form contains the VOR aerodrome
check-point sign (and marking).
Information signs have either a yellow
background with black message forms or a black
background with  yellow message forms. These
signs may be illuminated by internal or external
means, or they may be enhanced with retro-
reflective materials. The VOR check-point sign
can have one of several message forms: one
indicates that this is a VOR checkpoint, another
indicates the VOR radio frequency, yet another
denotes VOR bearing, and finally one giving the
distance to a VOR collocated DME unit.
Information signs for destinations include the
appropriate alphanumeric or word  abbreviation as
well as an arrow indicating the destination.
Aerodrome identification signs are installed
where visual identification of the aerodrome is
inadequate. The message consists of the name of
the aerodrome. No specific colors are given
though the colors selected should offer contrast
to the surrounding background of the sign. No
mention of illumination is made by ICAO.
Aircraft stand identification signs follow the
color pattern for information signs. It can be
illuminated externally or internally if
necessary.
36A3 Markings: Types and Messages
124
Markings can be divided into two principal
groups: runway-related functions and taxiway-
related functions. ICAO considers the markings
idinvidually without any intervening
distinction; nonetheless, they can be grouped
according to function without altering ICAO
order. White is the color used for all
markings. Visibility of markings can be
increased by outlining them in black.
Runway designation markings are found at the
threshold of paved runways. They are marked by
a two-digit number. If there are parallel
runways the number is supplemented by a letter.
The number is determined by a set formula based
on magnetic north. The letter is either L for
left, R for right and C for center. Three
runways would be marked by L, C, R and six
runways would be marked by that pattern twice
over.
Runway centerline markings are found on the
centerline of the runway between designation
markings. The centerline marking is composed of
equally spaced stripes and gaps. Each unit (one
stripe and one gap) is 50-75m in length. The
centerline for Category II and Category III is
.90m wide Category I and Code # 3, 4 (precision
instrument operations) require .45m wide
centerlines. Non-precision operations that are
code #1 and #2 are to be .30m in width.
Threshold markings are found at the
threshold of paved instrument runways and paved
non-instrument runways that are code #3 and #4.
They consist of longitudinal stripes grouped
around the centerline. A 18m wide runway would
have four stripes while a 60m wide runway would
have 16. Runways of other widths would have the
125
appropriate number of stripes for those widths.
The stripes are divided equally along the
centerline. They measure 1.8m by 30m with a
spacing of 1.8m. A transverse stripe is added
for a threshold separated from the extreme end
of a runway or where the runway centerline does
not square with the centerline. An arrow is
added for a displaced threshold.
A fixed distance marking is added for Code
#4 runways. It begins 300m from the threshold
and consists of two rectangles that are 45 to
60m in length and 6 to 10m in width. ICAO
describes them as "conspicuous rectangular
markings" but it is not clear what color the
markings are. They appear to be at variance
with the color of other markings.
Touchdown zone markings are added to
precision approach runways. The markings are
rectangular in shape and are arranged alongside
the center line. The length of the runway
determines the number of such markings. A
runway of less than 900m would have a single
pair which a runway at least 2100m in length
would have six pairs. There are two patterns to
follow: one pattern has single TDZ markings
throughout while the other pattern begins with
single stripes for the first two groups, double
stripes for the next two and triple stripes for
the last two. The first pattern has stripes
that are at least 3m wide and 22.5m in length.
The second pattern reduces the width to 1.8m.
Runway side stripe marking is installed
between thresholds in those cases where there is
little contrast between runway edges and
adjoining terrain. The stripes are at least .9m
126
for runways at least 30m in width and a minimum
of .45 m for narrower runways.
Taxiway centerline markings are a feature of
air operations on a Code #3 or #4 level. They
extend from runway centerline to aircraft stand
markings. It is recommended that such markings
be added to Code #1 and #2 operations as well.
The line is to be a minimum of 15 cm in width
and is a continuous line. The line is broken at
intersections with taxi-holding lines.
Taxiway holding markings are installed
adjacent to taxiway holding positions. There
are two patterns. The first consists of four
lines of which two are solid and two are
segmented. The four lines together are 1.5m in
width. Holding positions near runways employ
that form. The second pattern consists of two
parallel lines connected by cross bars. This
pattern is 1.20m in width.
Taxiway intersection markings can be
displayed where two taxiways intersect and a
holding limit is in effect. It can also denote
planes spacing safety limits. The marking
consists of a segmented line across the taxiway.
VOR aerodrome check-point marking consists
of a circle 6m in diameter with circle line 15cm
in width. A directional arrow can be added that
extends across the circle and extends beyond
culminating in an arrowhead. This form of
marking is used in conjunction with VOR
check-point signs.
Aircraft stand markings denote parking
positions. There are numerous elements that can
be included with these markings: alignment bar,
127
identification of stand, lead-in line, lead-out
line, stop bar, turn bar and turning line.
Alphanumeric symbols can be added to the lead-in
line. Character of lines and dimensions vary
according to function. Apron safety lines
delineate ground vehicle areas of operation.
These lines are continuous in form and at least
10cm in width.
I - -
Markings
, I
1 1 1 111
128
36B Indicators, Markers, Obstruction Markings
Restricted Use Markings
3631 Indicators: Types Messages
Indicator is yet another term that is not
easy to define. In aero aids it includes aids
that precisely define the direction a pilot
should go, or other information of a precise
nature. It applies to all lighted precision
approch descent indicators as well as wind cones
and wind tees. Frequently, references to wind
cones and wind tees are directly to those aids
without an overarching title; ICAO, however,
provides such a title.
ICAO employs more formal language for the
constituent elements of indicators; wind cones
thereby become wind direction indicators. Wind
indicators are sometimes termed wind socks
(Thorn Europhane 1992; Danaid 1991, WC-18).
ICAO 1990 describes the cone as a "truncated
cone made of fabric." ICAO 1983 provides only
limited information; however trade literature
and FAA supplies ample details. The wind cone
is mounted a pole that is either rigid with
hinges or frangible. The cone is connected to a
bearing assembly that allows even slight breezes
to move the cone. Wind cones can be either
lighted or unlighted. Illumination is provided
by flood lights mounted at the top of the pole;
an obstruction light may also be added.
The wind cone message is simple: wind moves
the cone and thereby indicates direction of wind
and, to some extent, the strength of the wind.
ICAO recommends one color for the cone; either
white or orange. If two colors are employed
they should be selected from orange/white,
129
red/white, or black/white. Two-color patterns
are arranged in alternating bands with the dark
color at the ends of the cone. A white circle
around the base of the wind cone is recommended.
In the event of multiple wind cones at an
airport there should be at least one that is
lighted, and one that is equipped with a white
circle.
Wind "Tees" are termed landing direction
indicators by the ICAO. They are constructed of
wood or metal. The tee is mounted on a
reinforced concrete pedestal equipped with a
bearing assembly for easy movement of the aid.
ICAO states that the tee is to be white or
orange though at least one maker, ADB, supplies
tees in aviation yellow (ADB A.08.410e).
Night-time use requires illumination of the tee
which can be accomplished by outlining the tee
or by other procedures. Tees that are outlined
with lights may have as many as 32 light
fixtures with half for each angle of the tee.
ICAO recommends white lights though older tees
approved by the FAA displayed green lights.
Some forms of the tee contain a mechanism that
limits the movement of the tee to predetermined
directions. An older publication of
Crouse-Hinds notes there are two functions for a
wind tee: indication of wind direction or of
recommended landing direction. Crouse-Hinds
further notes that wind tees can be free
floating (affected exclusively by the wind) or
remotely controlled (indicating landing
direction) (Crouse-Hinds 1962, 305-6A).
36B2 Markers: Types Messages
The physical  form and the message emitted by
markers are so closely related as to be
130
virtually one. This  is true, of course, for
many sign and non-sign markings (see for
example, Chapter 32F in Volume II, Part F,
International Railway Signals  in this series).
This is in contrast to lighted aids whose
physical apparatus and resulting messages can be
viewed as two elements. Markers frequently
display a significant vertical dimension in
contrast to markings which are characterized by
a horizontal dimension.
However, aero markers do not constitute a
monolithic entity. For example, some forms
display a substantially horizontal dimension.
How then do markers and markings differ?
Markings (this somewhat applies to traffic
control devices though there are differences
between aero and tcd forms) are usually in a
paint medium and therefore lack a dimension that
stands out from the surrounding surface.
Markers, by contrast, do stand out and more
often exhibit a vertical form than one that is
horizontal. Obstruction markings are vertical
rather than horizontal but they, like aero
pavement markings, do not stand out from the
surrounding surface.
It may be said that most categories of
transportation markings have a core identity and
the terminology and characteristics of those
forms of markings flow from that core image.
Other forms, while only partially conforming to
that identity, remain part of that core image.
An alternate view might suggest that some
transportation markings lack an independent
identity (or are too small to constitute a
category in their own right) and are simply
attached to some form that partially overlaps
with it.
131
ICAO standards are more general in character
than those of national standards (such as those
of the U.S. FAA). Nonetheless some general
comments can be made. There are two forms of
unpaved runway edge markers: flat rectangles
that are at least lm by 3m, or conical shaped
markers no more than 50 cm in height. Stopway
edge markers should be quite different in shape
so they are not confused with runway edge
markers. ICAO speaks of "small vertical boards"
for stopway edge markers. Snow-covered runway
edge markers can consist of evergreen trees
(which suggests a resonance of petit arbres in
marine aids to navigation) or "light-weight
markers". The later description is notably
vague; shape and other characteristics are
difficult to determine.
ICAO 1990 does not give actual shapes for
taxiway edge markers but it is quite possible
that they resemble those of runway edge markers.
Taxiway centerline markers are low-level though,
nonetheless, slightly raised above the
surrounding surface. The comments of ICAO may
suggest, or at least not rule out, retro-
reflective markers similar to those employed for
road centerline markers (ICAO 1983 notes that a
retro-reflective character was the single point
agreed upon as of that writing). Taxiway edge
markers for unpaved taxiways can probably be of
more than one shape; ICAO specifically mentions
one shape: conical-shaped markers. ICAO 1983
notes that taxiway markers are usually
cylindrical in shape; this may well be true of
other forms as well (it is true of ADB).
Cylindrical markers have a frangible pipe or
post if the actual marker is rigid. Some
markers "bounce back" if run over and do not
require a frangible character.
132
Boundary markers, by contrast, are presented
in some detail. They can have the shape of a
low-level triangular-shaped object long in
length and narrow in width. They can also
exhibit a conical shape which suggests a form
approved for runway and taxiway markers.
It has been noted that retroreflective
markers are becoming more common. This may have
been influenced by more readily available
reflector materials. It has been influenced as
well by the advent of MLS which allows for
simpler lighting  systems and greater use of
reflective markers (Pollock 1990, 35, 37).
The matter of messages appears to be
fragmentary and somewhat chaotic. ICAO 1990
specifies color for taxiway markers only. ICAO
1983 indicates color code discussions were so
far incomplete. That same document indicates
taxiway markers can be employed for unlighted
taxiway situations while ICAO 1990 refers only
to unpaved taxiways.  The ADB  catalogue (1991)
states that an ICAO color code for both taxiways
and runways is extant (ADB 1991 A.03.710e).
That same catalogue presents the following color
configurations: a yellow post or pipe for runway
markers with a sheath or sleeve of white;
taxiway markers are blue for post and sleeve
while taxiway center line markers are green in
color.
ICAO 1983 includes Swedish material on
boundary markers that can presumably be applied
to those markers in general. Sweden has
developed a form of boundary marker to denote a
slope below runway markers. The boundary marker
units are arranged in a zig-zag pattern to
denote the slope. The color pattern is made up
133
are orange and white; red and white are an
acceptable alternative. Either orange or red is
used 
.
when a single color is required.
Spherical markers are attached on the object
in such a way that the general shape of the
object is retained. Spherical markers are
placed on problems areas such as overhead wires
and cables. Spheres should be at least 60 cm in
diameter. Individual markers are of a single
color and the markers are placed in an
alternating arrangement: white and orange or
white and red.
Flag markers (ICAO refers simply to flags
while FAA refers to flag markers; it seems more
consistent to speak of spherical markers and
flag markers than to speak of markers - which
turn out to be spherical - and flags). Flag
markers are situated on the top or uppermost
edge of an object or around an object. They are
positioned 15m apart and are to be at least .6 m
square. Such markers can be solid orange or
composed to two triangular swatches, one white
and one orange. FAA permits checkerboard
pattern as well but that form is not found in
ICAO (FAA 1991 OML, 7).
36B4 Restricted Use Area Visual Aids
There are four aspects to "Visual Aids for
Denoting Restricted Use Areas" to employ the
ICAO term. They include closed runway and
taxiway aids, non load-bearing surface aids,
pre-threshold area aids and unserviceable area
aids. Closed markings are located at or near
the end of the closed area. They consist of a
cross whose arms are .9m by 6m at a minimum and
are white or yellow in color. The cross is
136
often termed a Saint Andrew Cross though that
term is absent from ICAO coverage.
Non load-bearing surfaces markings denote
areas that cannot take a plane weight but that
are indistinguishable from load-bearing
taxiways, holding bays, aprons and other similar
situations. They are marked by taxiway side
stripe lines which is comprise of a double line
at least 15cm in width with 15cm minimum spacing
between lines. The color is that of taxiway
centerline marking.
Pre-threshold markings are areas more than
60m in length that are not capable of regular
aircraft usage. Such areas are marked by
chevrons in a recommended color of yellow. The
chevrons are at least 15m in length and 30m
apart.
Unserviceable area aids are more complex.
They can contain lighted forms which are
considered with obstruction lighting. These
areas are not suitable for aircraft but they are
also areas that can be skirted by aircraft.
They may include, for example, an area
containing potholes or a construction zone. The
markings are arranged so as to outline the area
of concern. These aids take the form of markers
except for those that are lighted. The markers
can be flags, cones, or marker boards. Cones
can be red, orange, yellow or a combination of
white and any of those colors. Flags follow the
same norms for colors as cones. Marker boards
display vertical stripes that are red and white
or orange.
137
H
W
CHAPTER THIRTY-SEVEN
ELECTRONIC AERO NAVIGATION AIDS
37A FULLY INTEGRATED SYSTEMS
37A1 Chapter 37: Overview Changes
The taxing problem of terminology is
addressed or at least broached elsewhere in this
monograph. For this chapter electronic aero
navigation aids or radio aids will suffice for
terms though they do not eliminate the problems
of terminology. One point of illumination for
this problem is found in an AI article (Olsen
1992, 12) in which the author notes that an ILS
is "not strictly a nav aid." Olsen in a 1990
article notes that in 1970 "navaids include.
VOR/DMEs and NDBs (Olsen 1990, 37). Both
statements confirms the suspicion of this writer
that aviation experts count as navigation aids
only those aids strictly and directly involved
with navigation in a precise way. Yet that
means not only lighted aids for aircraft moving
on the ground but all aids - including radio
aids - employed for approaching an airport
seemingly fall outside of a strict sense of
navigation aids. Though, to adopt a marine
viewpoint, navigation aids can pertain to all
aspects of the movement of a marine craft from
dock to waterway and to dock and all aids are so
regarded. In this chapter all electronic aids
are navigation aids even though that may merit
criticism in some quarters. The literature of
aero navigation at times speaks of CNS:
communication, navigation and surveillance
139
systems and this provides a larger context for
viewing aero navigation aids (Olsen 1991, 12).
ICAO materials, of course, were vital for
this treatment. Annex 10,  Aeronautical Tele-
communications was the primary resource.
Articles from AI were also of notable value for
the coverage.
Foundations  (Part A, 2nd ed in this Series)
offers reflections on electronic concepts
including both theoretical and applied
dimensions. The reader can consult that
monograph for background and adjunct material on
that topic. This chapter considers changes in
navigation aids that are underway as well as the
various navigation aids in their present state.
Navigation aids are considered in two
groups: fully integrated systems (37A) which
consists of ILS and the developing topic of MLS;
and independent and partially integrated systems
and multi-mode systems 37B). The later group
includes beacons (both directional and
non-directional), and multi-mode aids. By
multi-mode are meant aids that are shared with
the marine commmunity: Loran, OMEGA and
satellite navigation. Previously mentioned
beacons may be stand-alone aids or aids in
conjunctions with other aids. Multi-mode are
included since they aero-related and thereby
require examination. Loran and Omega are
considered only briefly since they are reviewed
in the marine monograph. Many of the
traditional aids can be viewed as "point-source
aids since the information that they emit is
"relative to the point on the earth surface at
which the aid is located." This is in contrast
140
with many newer aids that are hyperbolic in
nature (Olsen 1990, 37).
A review of ICAO and other publications, and
perhaps this study as well, may suggest a stable
and solid situation with aero aids. However,
that stability and solidity are accompanied by
uncertainties as well. Traditional aids, such
as ILS, VOR/DME and especially NDB, may be in a
transitional state while MLS and satellite
systems may eventually eclipse and overwhelm the
older aids. However, many of the older aids
continue to hang on. In some cases older aids
have undergone revitalizing with some increase
in numbers. At least one expert, in viewing the
ILS-MLS situation, has asked whether it is a
matter of "when, if even, to phase out ILS
rather than when to implement MLS." (Olsen 1990,
42).
Indications of the decline of conventional
aids can be easily found. For example, Olsen
(1990, 37-42) notes that in 1970 VOR/DME
dominated world air routes, that NDBs were
commonplace, and most industrialized states had
aero aids equipment manufacturing concerns. But
in 1990 the NDB is no longer approved by ICAO
(though ICAO publications do not appear to state
that is the case; Olsen 1991-1 does speak of a
gradual withdrawing of NDBs), DME is replacing
ILS Locators, and aircraft-based systems have
reduced the value of VOR. The ILS and MLS
controversy continues and ICAO is looking toward
navigational satellites. IATA holds the view
that VOR/DME are only needed in terminal areas;
nonetheless, they continue to fulfill a larger
role. In fact Russia is implementing a vast VOR
system across the breadth of that nation (Olsen
1990, 42).
141
But signs of the continued importance of
such aids are also available. Hyperbolic
systems, such as Omega and Loran-C, have
advantages over VOR though neither of those
systems has an open-ended future. Loran-C was
supposed to be phased out yet remains a popular
aid. And VOR still has a dominant role; DME
along with VOR will still be in use at least for
the early part of the 21st century. NDBs, for
example, remain vital in many areas including
northern Canada. Eventually GNSS will become a
significant alternate in Canada yet the
usefulness of NDBs will continue for quite some
time (Canada 1992 ANSP, 9-14).
ILS was scheduled to be eliminated by the
year 2000 (at one point MLS was to be the
officially sanctioned aid by 1995 then that was
moved forward to 1998 (Buttersworth-Hayes 1986,
23-27; Glines 1989, 27). But many sceptics of
MLS remain unconvinced and new ILS equipment is
finding a market. Eventually MLS may yet become
dominant. ICAO has had conferences on satellite
navigation and other navigation and
communication concerns under the acronym FANS or
Future Air Navigation System. FANS topics
include Global Navigation Satellite Systems or
GNSS (which includes U.S. GPS and Russian
GLONASS). References for FANS include MLS:
Setting the Future Standards 1984, 31ff;
Buttersworth-Hayes 1985, 36-37; Olsen 1991-1,
28; Olsen 1991-2, 12ff; and Fans 2 1990, 16.
37A2 Instrument Landing Systems (ILS)
The purpose of the ILS is to create an
approach path for aircraft on the final approach
to landing; it includes both azimuth and descent
information. Components of such a system
142
include two directional transmitters (localizer
and glide slope), and two or three marker
beacons. A DME may serve as a replacement for
the outer marker beacon and, according to one
source, and DMEs are replacing localizers for
ICAO. A locator (compass locator for the US)
can replace outer marker or middle marker
beacon. The ILS supplies guidance, range, and
visual information. The last-named function is
considered in Chapter 36. This treatment of ILS
has been substantially guided by U.S. AIP (ATP
1991, 0-8 to 0-10); ICAO documents have also
been consulted.
The Localizer unit provides lateral guidance
for aircraft approaches. Specifically, it
provides course guidance for the runway
centerline. It broadcasts on a VHF frequency
between 108.10 MHz and 111.95 MHz. The VHF
signals are modulated with two navigation tones
at 90Hz and 150Hz. The identification signal is
in Morse code and consists of two or three
letters preceded by the letter "I". The 90 Hz
tone denotes the fly right indication while the
150 Hz denotes the fly left message. The
antenna array is situated on the far end of the
runway from the approach end and consists of
short masts across the far end of the runway
with shorter masts radiating out from the
vertical masts. Other elements of the physical
plant include an equipment hut, transmission
equip- ment, monitoring and control equipment.
An on-course position results in an equal tone
from fly left and fly light indicators and the
needle thereby denotes on-course status.
The glide slope provides angle of descent
information and thereby denotes minimum decision
height (DH). The glide slope broadcasts on a
143
UHF frequency between 329.15MHz and 335.00MHz.
Modulation frequencies are 90Hz and 150Hz and
also give guidance data. There is no
identification signal. The glide slope is
paired with the localizer thereby creating a
single ILS aid. The physical aspect includes an
equipment hut, transmitter, antenna, and
monitoring and control equipment. There are
several different antennas that can be used for
a glide slope.
The receiving unit for the localizer and
glide slope can display a double gauge. The
localizer gauge displays a vertical needle which
indicates whether the aircraft should go to the
right, or to the left or whether the aircraft is
on target. The glide slope gauge displays a
horziontal needle that indicates whether the
plane should fly up, fly down or is on course.
The 150Hz signal denotes fly-up and the 90Hz
signal denotes fly-down. The center point
between signals indicates on course.
Marker Beacons denote points in the approach
path for ILS. The beacons emit a vertical
pattern that creates a horizontal elliptical
pattern; the frequency is 75MHz. In many
instances there are two marker beacons: an outer
beacon and an inner beacon.
The Outer Marker Beacon is four to seven
miles from the runway threshold. The modulation
frequency is 400Hz. It marks the intercept
point for the glide path procedure turn
altitude. The message pattern displays two
dashes in Morse code with a blue light for the
reception end. A gauge with as many as three
lights can display this and the other beacon
messages.
144
The Inner Marker Beacon is 800-1500 feet
from the threshold. The modulation frequency is
3000Hz. It denotes decision height (DH) of 100
feet above touchdown zone highest elevation.
The Morse code message consists of six dots and
the light is white.
The Middle Marker Beacon, when in use, is
2000-6000 feet from the threshold. It denotes
the decision high point. It gives an amber
light and Morse code dot dash message pattern.
In some instances a Back Course Marker Beacon is
employed. It has a modulation frequency of
3000Hz and emits a dots pattern in white light.
Outer Marker Beacons consist of dipole
antennas (which is a basic form of antenna and
one that is the source of many other antenna
forms; Turner defines it as a "center-fed signal
with a half-wave length long that is suitably
corrected for end effects." and mounted over a
counterpoise (Turner 1991, 398). The equipment
hut would be near or beneath the counterpoise.
Compass locators share the same shelter. New
versions display vertical array antennas with a
solid-state transmitter.
Locators or Compass Locators (which is a NDB
when used in ILS) serve as a supplement for
Marker Beacons for the U.S.(AIM 1991, 1-1-6)
(and as a replacement for such beacons in ICAO.
They operate on a frequency between 200 and
415kHz. The message is in Morse code and has
two letters. The outer locator transmits the
"the first two letters of the localizer
identification group" while the middle locator
has the last two letters.
37A3 Microwave Landing Systems (MLS)
145
MIS gains its name from the frequency it
employs: the 5 GHz microwave band. This
frequency greatly reduces the problem of
multipath (multipath transmissions consist of
two or more paths with one part from the
transmitter while another path reflects off
objects (Turner 1991, 398). Multipath, to which
ILS is prone, lowers the quality of signals and
is common to mountain areas (and even less
rugged terrain) and in diminished weather
conditions (rain and snow). There are 200
channels that MLS can use instead of the 40 for
ILS. The signal is of higher quality and gives
a more rapid indication if an aircraft
approach path is inaccurate (MLS: Setting the
Standards in AI 1984, August/September). MLS is
generally seen as a landing system though it has
also been seen as both a landing and departure
system (Olsen 1990, 42).
MLS creates a cone shaped radiation pattern
that is 40 degrees in width and 0 to 20 degrees
for elevation. The azimuth function of MLS
consists of a microwave beam that continuously
travels over that degree range and the elevation
portion does the same for that phase. Pulse
measurement creates an exact determination of
the aircraft position. ILS equipment
indicates if on or off and periodic indications
of distance to threshold but it can not supply a
continuous stream of data. MLS  will  not require
straight courses as is the case with ILS.
MIS is able to meet the navigation needs of
STO1 and V/STOL in contrast to ILS. In part
this is because angles of descent of more than 3
degrees are possible with MLS (Butterworth-Hayes
1985, 36 and 1986, 23).
146
A P-DME (Precision DME) with MLS supplies a
continuous data flow as well. DME/P is a
variant form known as Precision DME or DME/P
with greater accuracy than the more familiar
form. Other forms include DME/N and DME/W.
DME/N uses enroute navigation with narrow
spectrum; DME/W enroute with wide spectrum. ICAO
recommends no further W after 1987 (ICAO 1987,
4, 27, 28) .
The MLS azimuth station occupies a position
similar to that of ILS localizes at the far end
of the runway. The azimuth station scans the
width of the runway twice per cycle; the first
scan (the "TO" scan) begins the right side of
the beam swath and continues to the left side of
the swath. At a predetermined time it scans in
the opposite direction (the "FRO" scan). The
airborne unit picks up both signals, calculates
the time readings and determines the aircraft
angle of approach.
The MLS elevation station occupies a similar
position to ILS glide slope: about 1000 feet
from runway threshold. The station performs a
similar action but in a vertical direction: up
then down. And again, the aircraft receiver
takes in the signals, calculates the readings
and determines the elevation of the aircraft.
147
37B Independent Partially Integrated Aids
37B1 VOR, TACAN, VORTAC DME
ICAO is primary for all aspects of the study
including this segment. But other resources
have enhanced that core resource. Clausing
1987 treatise entitled, The Aviator Guide to
Modern Navigation greatly aided the treatment
(especially Ch 2, "VOR Navigation Fundamentals"
and Ch 4, "VOR/DME Navigation"). Grover 1957
work  entitled, Radio Aids to Navigation also
supported the treatment of 37B1.
Azimuth (directional) and distance (or
position) information can be supplied by several
forms of radio aids or combinations of such
aids. The principal azimuth aid is the VHF
Omnidirectional Range (usually referred to as
VOR). The Distance Measuring Equipment (DME) is
the comparable aid for position data. TACAN and
VORTAC can also supply this information though
they are not ICAO-sanctioned. Since they are
approved by NATO and many nations active in
aviation are members of NATO those aids are also
included.
The VOR has been an important aid for more
than 40 years. It took hold in the U.S. before
becoming commonplace in other nations. It has
been adopted by ICAO as the standard short range
aid and eventually found global usage.
An older and once common aid, the MF four-
course radio range, transmitted four narrow
tracks while VOR in effect broadcasts 360 tracks
since it is omni-directional. VOR transmits on
a frequency between 108.0 and 117.95MHz with
148
modulated coded tone at 1020Hz for identi-
fication. The VOR transmits two signals. One
is constant and denotes the VOR installation.
The second indicates the position of the
aircraft in relation to the VOR aid. The
transmitting signals also include an identi-
fication message for the VOR unit. This is in
Morse code. Many VORs have a voice transmission
that can also identify the station as well as
give other information.
The VOR can be viewed as a passive system
since the unit continuously sends out signals
without prompting by airborne navigational
equipment. This contrasts with DME which is an
active system.
The VOR indicates the radial that an
airplane is on it does not indicate the actual
position of the aircraft. The azimuth or
directional data denotes relationship to a VOR
but the plane could be anywhere on that radial
from near the VOR to a considerable distance
away. An additional aid is needed for position
information. This unit is the DME or Distance
Measuring Equipment facility.
DMEs are separate from VOR units but they
can be seen "as essentially equal partners in an
integrated system of navigation... ." (Clausing
1987, 38-48). Many VOR and DME units are
colocated and thereby create a unified aid.
DMEs are UHF rather than VHF and broadcast on
frequencies between 962 and 1213 MHz with a
modulated coded tone at 1350 Hz for identi-
fication (this is true for TACAN as well).
Since the DME is an active unit it needs to be
triggered before it will operate; the triggering
mechanism is aboard the aircraft seeking to use
149
the DME. The DME is a form of transponder and
when activated sends out pulses indicating
position data. The two signals, one outbound,
one inbound, constitute a cycle and the time
that elapses in the transmission is translated
into nautical miles or kilometers and thereby
gives the aircraft position. The onboard
indicator displays a mileage meter and
accompanying arrow indicator. DME has three
versions: en route, landing and precision (Olsen
1990, 39).
The TACAN system was developed by the U.S.
military to meet special military needs (such as
the "rolling and pitching" of an aircraft
carrier deck) (AIM 1991, 1-1-3). TACAN includes
both azimuth and distance measuring
capabilities. The DME function of TACAN is
identical to that of the earlier described DME.
However, DME for TACAN is an integral element
rather than something "tacked on". Tacan
broadcasts on UHF frequency in the 960-1215 MHz
range. It is a pulse system. Airborne
equipment translates the pulses into a visual
form for both azimuth and distance information.
VOR and TACAN are separate units but since
the airways served form a single system many VOR
and TACAN units are located together. This
results in VORTAC; it forms a single system with
two elements: VOR and TACAN. Azimuth
information is broadcast on both VOR and TACAN
with DME on the TACAN portion only. The DME
portion is the same whether a VOR/DME or VORTAC
assemblage. A military aircraft can use the
TACAN while the civilian pilot employs VOR and
the DME part of TACAN. TACAN transmits on the
same frequency as DME. The receiving unit
150
displays visual information for both azimuth and
distance aspects.
VORTAC and TACAN are often employed by NATO
nations; less often found in other states. For
example, Norway, Denmark, France, Belgium employ
VORTAC and TACAN while Switzerland, which is not
a member of NATO, does not do so though
surrounded by Vortac and TACAN users. Some
non-NATO users do employ those systems; for
example, Taiwan. (AIP and other materials from
nations referred to provide the references).
ICAO includes VOR without mention of a form
of VOR known as TVOR or Terminal VOR; U.S. FAA
does include TVOR. A form of VOR known as DVOR
refers to a variant form that utilizes the
Doppler effect. DVORS present a purer signal
since they are less affected by rough terrain
and built-up areas. DMEs are also associated
with ILS and MLS and will  be alluded to in that
context.
37B2 Beacons Multi-Mode Radio Aids
This segment takes up both directional and
nondirectional beacons; this approach
corresponds to ICAO category of Radio Beacons
consisting of nondirectional beacons and marker
beacons. Marker beacons are directional in
form. Multi-mode aids (radio aids shared by
aero and marine navigators) are considered in
Foundations  (Part A, 2nd ed). and International
Marine Aids to Navigation  (Parts CID, 2nd ed).
However, a brief review of selected multi-mode
aids is included in this segment.
Nondirectional beacons, usually known by the
acronym of NDB, is a LF or MF aid in the 190-535
151
kHz range (Clausing 1987, 78 TISRP). There are
four types of NDB: the Compass Locator in ILS
which is addressed there; the NDB  approach aid
in which the NDB  is the primary approach system;
the en-route NDB;  and finally, high-powered NDBs
from coastlines to offshore points. Marine
radiobeacons are separate from aero forms though
they too are NDBs.  Clausing notes that any AM
radio transmitter, even an AM broadcast station,
could become a NDB  as long as the transmitted
signal goes in all directions. And the
frequency range is just short of the AM range.
NDBs  remain a vital radio aid as indicated by
AIP and other publications of many nations. It
is especially important as both an approach aid
and en route aid over large territories such as
that of Canada.
The message consists of two parts: a
continuous tone in the aforementioned frequency
which is amplitude modulated by an identi-
fication signal in Morse code in  either 400Hz or
1020Hz frequency; voice modulations are also
sometimes present (FAA 1986-7, 47; also AIP
1991, 0-6; Clausing 1987, 87 for remainder of
paragraph). The Morse code signal usually
consists of three letters in the U.S. and either
two or three letters elsewhere; Compass Locators
have two letter indications. The reception end
of the process requires an automatic direction
finder (ADF). The ADF includes a receiver, two
antennas (sense, and loop forms) and an
indicator. The message is received on a gauge
termed a compass card which displays bearing
numbers and an arrow. A second unit contains a
sound or aural unit for receiving the
identification signal from the NDB  and a
mechanism for selection of the correct
frequency.
152
Marker beacons are a major component of ILS
and are discussed in that context (AIP 1991,
0-9). Marker beacons employed for en route
purposes are included here. They are a VHF aid
and transmit on a frequency of 75 MHz. There
are three forms of the aid: Fan Markers, Low
Powered Fan Markers and Z Markers. These
markers are familiar to users of the older four
course radio range aid. Fan or cone markers
denoted radio ranges while Z markers denote a
point between radio range stations. ICAO
specifically mentions the use of markers for
radio ranges though that appears to be an
obsolete aid.
Identification of the aid, when required, is
through Morse code. The message is frequently
"R" (.-.) though other letters can be employed.
The message can be a simple one of light and
sound (hum) received in an airborne unit (AIM
1991, 1-1-5).
Grover in his 1957 (30-33 TISRPS) work notes
that ICAO in 1954 recommended Consul as an
"interim aid" until more modern aids were
available. This applied to Loran as well. And
in the latest (1985) edition of Annex 10 Consul
is still included along with Loran-A which is an
older version. Consul stations are found at
several points in western Europe.
Consul, a descendent of the German Sonne, is
a MF aid in the 255-415kHz range. It has proven
to be an accurate aid with a considerable
distance of 1500km. The transmitter unit is a
single unit but with three antennas the signals
gives the appearance of rotation. It is an
omni-directional aid displaying a dot dash or
dash dot Morse code signal. The complete cycle
153
consists of the basic message then a long dash
followed by station identification and another
long dash. IHB 1965 supplies information on
Consul and Sonne as well.
Loran-A is a MF aid in a frequency range of
2MEz and follows a time measurement pattern with
pulses emitted from a master and two slave
stations. Aircraft equipment consists of a
cathode ray oscilloscope that records the time
from the incoming signals. The time differences
can be employed to establish lines of position
of the aircraft (Grover 1957, 63-64; see also
IHB 1965). ICAO includes Loran-A rather than
Loran-C yet the former is obsolete or nearly so
and the later is still in use. Some relatively
recent sources have viewed Loran--C as
increasingly important for general navigation
yet signs of its demise are also in evidence
(Underwood 1987, 34ff).
Satellite navigation is not fully
operational though it will in all likelihood
become a vital element. Two systems well along
in development are the U.S. GPS (Global
Positioning System) and the Russian GLOSSNASS.
A 1991 agreement called for a GPS and GLOSSNASS
network that would constitute Global Navigation
Satellite System (GNSS). GPS operates on two
UHF frequencies: 1575.42MHz and 1227.60MHz. It
has two levels of accuracy: military and
civilian. The former is accurate to within 16
meters while the later is accurate within 100
meters. There are few limitations on the
system. It is accurate at any time of day, or
season or weather conditions. Neither do solar
disturbances materially affect it. Satellites
are very costly but receiver units are
comparable to VOR/DME equipment. The complete
154
GPS operation will have 21 satellites.
References for this material include Canada ANSP
1992, 9-15; Blacklock 1991, 13; see also Olsen
1990, 37-42;, Clausing 1987, 169-179; and
DOT/DOD 1992, 3-38 to 3.44; GNSS and Future Air
Navigation System (FANS) resources include Olsen
1991, 12f, FANS 2 ... 1990, 16).
Haken Lans (GP Systems, Stockholm) sees
satellite navigation as replacing "all existing
navigation techniques." This results in a new
global standard for navigation. GP Systems has
the goal of "integrating GPS fixes with
different types of guidance and information
systems." The new way can include enroute,
precision approaches and even taxiway movements
(Blacklock 1991, 13). Satellite navigation and
MLS have been seen as forming a system meeting
future navigation needs (Olsen 1990, 38).
GPS is a time measurement system. Time
elapsed from satellite to receiver is multiplied
by speed of light to gain a line of position.
Three measurements result in latitude, longitude
and altitude measurements. GPS is a passive
system that continuously sends out data and does
not need to be triggered. The receiver/computer
takes in data from three satellites and computes
the precise location of the aircraft. Because
of the possibility of ionospheric disturbances
signals are received on both frequencies. This
allows for determination of any alterations due
to the disturbances and for the correction of
the flawed data. The process of receiving and
calculating data is complex and requires the
computer operation. The receiving assemblage
consists of antenna, receiver/processor, and
control-display unit.
155
Differential GPS has been developed for
precision local navigation needs. In this
system data is received from five or more
satellites. Differences in the received data
produce accurate fixes in the immediate area of
the plane (Hobbs 1990, 587). Wilcox, to cite
one example, has produced a Differential GPS
(DGPS) with data receiving equipment units at
airports. Accuracy of data is one to two meters
(Wilcox 1993). DGPS augments satellite
transmissions with corrections in data for
aircraft (Blacklock 1991, 13).
The "Attachments" (a form of appendix) of
the various editions of Annex 10, Aeronautical
Telecommunications  include references to aids
little mentioned in contemporary publications on
electronics and navigation. These aids seem to
occupy a borderland between history and current
practice. They are included here if only
briefly.
Long distance aids in this category include
Delrac, Dectra, Navaglobe and Navarho. Both "D"
aids are part of the Decca company system, a
British concern. Dectra focusses on a single
route (in contrast to a system such as Consul).
It is a directional aid of great accuracy and is
designed for long distance navigation such as
the North Atlantic. It is based on the
techniques found with Decca. The system is
termed a "track guide system" with two pairs
(chains) of stations: two masters and two
slaves. The transmissions form hyperbolic
patterns and the messages are received by a two
156
airborne meters. One meter denotes relation of
plane to track (whether to left or right) and
the second indicates distance flown. Grover
1957, 114-117 was the principal reference to
this coverage. IHB 1965 II. 3-2-29 to -31
provides coverage on Dectra as well as extensive
coverage of Decca. ICAO publications discuss it
very briefly.
Delrac (Decca Long Range Area Coverage)
provides area coverage rather than track
coverage. Delrac is a LF system and is highly
accurate. It too is hyperbolic. The line of
position provides a fix indicating the plane
position. It is a phase comparison as is
Dectra. The proceses are also similar to Decca
(Glover 1957, 117-118).
The Navarho and Navaglobe systems are of
American provence. Navaglobe was an area
coverage approach while Navarho was of
directional form. ICAO, according to Grover,
expressed a preference for Navarho over
Navaglobe. However, ICAO presents the two as a
hyphenated single system. All four systems
appear in ICAO in the 1960s but have not been
included for quite sometime.
Navaglobe measured distances through two
transmitters while Navarho provided bearing and
distance data from three transmitters. The
three transmitter system are arranged in the
form of a triangle. The station transmitts one
pulsed message for each pair of transmitters
(the three transmitters are paired in turn
providing three pairs and hence, three messages)
then all three stations transmit together. The
combined message is synchronized and broadcast
on two frequencies. The aircraft equipment
157
receives the three transmissions and by a
comparison of them gains bearing information.
The reception of the fourth signal allows a
comparison of the two frequencies phase
differences with that of a airborne oscillator
unit which results in distance information. It
would have required fifty stations globally to
create full coverage for Navarho (Grover 1957,
118-119).
ICAO includes mention of two short range
aids as well. These are GEE and VHF Multi-track
pulse range. GEE can also serve as a medium
range aid hyperbolic in nature with considerable
accuracy. It consists of a master station and
two or three slave stations. GEE creates lines
of position as do other hyperbolic units but
unlike some systems it can create multiple lines
of position at one time (Grover 1957, 55ff).
VHF multi-track system contrasts with VOR or VHF
omni range system; information on the
multi-track system is very limited.
158
APPENDIX
COMPARATIVE SURVEY OF ICAO-SANCTIONED AERO AIDS,
1949-1990
i General Considerations
This monograph has been heavily influenced
by ICAO and its publications. So far in the
study it has not been possible or appropriate to
review the publications of ICAO with their
structure and treatment of aeronautical navi-
gation aids. This appendix will offer such a
review.
ICAO treatment of Visual Aids has taken two
forms: the first from 1951 (first edition) to
and including 1971 (6th edition), and the second
from 1976 (seventh edition) to 1990 (first
edition of a split coverage: Volume I, aero-
dromes and Volume II, heliports). There is a
significant alteration between the first
editions and the more recent ones. Though it
can be noted that the many differences over four
decades does not fully eclipse many points of
commonality.
The first three editions evince a complex
structure: general items, aerodromes with
runways, aerodromes without runways (with both
lighted and unlighted aids in each category),
and water aerodromes. The next three follow
that pattern but eliminate water aerodromes.
The three more recent editions are greatly
simplified with all non-obstructions aids in a
single chapter under the heading of "Visual Aids
for Navigation". Obstruction aids and aids for
restricted areas occupy separate chapters.
159
Radio Aids, while occupying more editions,
follows a similar pattern over the decades
though some increase in types of aids has
occurred. Radio aids represent far fewer
varieties; hence a greater commonality. The
original edition, that of 1949, is not numbered.
And the first edition, 1950, omits the words
first edition from the publication. The other
editions have these dates: 2nd ed, 1951; 3rd ed,
1952; 4th ed; 5th ed, 1958; 6th ed, 1960; 7th
ed, 1963. 1st ed of split edition (Vol I),
1965; 2nd ed, 1968; 3rd ed, 1972; 4th ed, 1985.
The Attachments in Radio Aids mention other
aids and these aids have been included at the
conclusion of the review of Radio Aids. They
may be more of historical interest than current
systems.
ii Visual Aids: Lights
a) Visual Approach Slope Indicators
1st ed, 1951 2nd ed, 1953, None
3rd ed, 1958 4th ed, 1964, VASIS
5th ed, 1969, Above AVASIS
6th ed, 1971 and 7th ed, 1976, Above
3-BAR VASIS, 3-BAR AVASIS, T-VASIS,
AT-VASIS
8th ed, 1983 1st ed, Vol I, 1990,
Above PAPI APAPI
1st ed, Vol II, 1990, PAPI, APAPI, HAPI
b) Approach Light Systems
1st ed, Approach Lighting System
Type "A", and Angle-of-Approach Lights
2nd ed, Approach Lighting System for
Runways with Neither Stopways nor
160
Displaced Threshold, Lead-in Lighting
System for Runways with Neither Stop-
ways nor Displaced Thresholds,
Approach Lead-in Lighting Systems
for Runways with Stopways, Approach
Lead-in Lighting Systems for Runways
with Displaced Thresholds, Angle-of-
Approach Lights
3rd ed, Precision Approach Runways
4th ed, Above Simple Approach Light
System,
5th ed 6th ed, Simple Approach Light
System Precision Approach, Category I,
and Category II
7th ed, 8th ed, and 1st ed, Vol I, Simple
Approach Light System, Precision Category
I, and Precision Category II III
1st ed, Vol II, Heliport Approach Lighting
System
c) Runway Taxiway Lights
1st ed, Runway Lights, Runway
Threshold Lights, Taxiway Lights
2nd ed, Above Stopway Lights
3rd ed, Above TDZ Lights, Fixed
Distance Lights, Taxiway Guidance
System One other item-Check
4th ed, Above Runway Centerline
Lights, Runway Edge Lights, Taxiway
Centerline L., Taxiway Edge L.
5th ed, Above Runway End L, Exit
Taxiway Centerline L. on High Speed
Exit Taxiway
6th ed, Above Exit  Taxiway Centerline
L. on Other Exits
7th ed, Above Runway Threshold Wing
Bar L., Clearance Bars
8th ed, Above Taxi Holding-Position  L.,
161
VDGS and ASMGL
1st ed, Vol I, Taxiway Guidance System
no longer present
d) Boundary Range Lights
ist to 6th editions inclusive; originally
found with Water Aerodromes Land Aero-
dromes without Runways
7th, 8th, and 1st ed, Vol I, II, no longer
listed
e) Beacons
All editions, Aerodrome Beacons and
Identification Beacons
f) Obstruction Lights
1st to 6th editions, Obstruction Lights, and
Hazard Beacons
7th ed to present, Obstruction Lights
divided into Low, Medium and High
Intensities
iii Visual Aids:
Indicators, Markers, Markings Signs
a) Indicators
Wind Direction Indicators, All editions
Landing Direction Indicators, All editions
b) Approach Day Marking System
1st to 3rd editions, beyond that?
c) Runway Markings
162
Boundary Day Markings, 3rd-6th eds
Day Marking - Landing Aids,
Day Marking Aids, 2nd ed
Day Marking of Snow-covered Runways,
2nd ed
Displaced Threshold Markings, 4th-6th eds
(The word Runway added in 2nd ed;
Temporarily added before Displaced in
3rd edition)
Distance-to-go-Markings, 4th-6th eds
Fixed Distance Markings, 3rd-8th eds,
Land Aerodromes w/o Runways Day Marking,
1st ed, 3rd ed,
Paved Runway Day Markings, 2nd ed
Paved Runway Markings, 3rd-6th editions
Runway Caution Zone Markings, 1st ed
Runway Centre Line Markings, all editions
Runway Designation Markings, all editions
Runway Edge Markings, lst-6th eds
Runway Longitudinal Markings, ist ed
Runway Side Stripe Markings, 2nd onward
(The word runway added in 6th ed)
Runway Threshold Markings, all editions
(The word Runway dropped with 4th ed)
Stopway Day Markings, 2nd, 3rd, 5th eds
Touchdown Zone Markings, 3rd-8th eds,
Unpaved Runway Edge Markings, 4th ed
Unpaved Runway Markings, 2nd-6th eds
(The word Day added before Runway, 2nd
ed)
VOR Aerodrome Check-Point Markings, 6th-
8th eds
Water Aerodromes Day Marking, 1st, 3rd eds
(Ends with Landing Aids in 3rd ed)
d) Taxiway Markings
Aircraft Stand Markings, Bth, 1st-Vol I,
163
Apron Safety Lines, 8th, 1st-Vol I
Category II Holding Position Markings,
6th ed
Category II or III Holding Position Marking
7th (Within Taxi HP in 8th, 1st, Vol I
eds)
Day Marking - Taxying Aids, 2nd ed
Paved Taxiway Markings, lst-6th ed
(Day after Taxiway in 2nd ed)
Taxi-Holding Position Markings, 3rd-
1st, Vol I eds
Taxiway Center Line Markings, 5th-lst,
Vol I, eds
Taxiway Day Markings, 1st ed only
Taxiway Guidance System, 4th-6th eds
(Stop Bars, Clearance Bars under TGS
in 6th ed)
Taxiway Intersection Markings, 8th,
1st-vol I,
Taxiway Longitudinal Markings,
Taxiway Side Stripes Markings, 6th-lst,
Vol I eds
Water Aerodromes Aids to Taxying, 1st ed
Unpaved Taxiway Markings, 2th-6th eds
(The word Day precedes Markings in 2nd)
e) Obstruction Markings
Colors, All editions
Flags, All editions
Markers, All editions
Visual Aids for Denoting Restricted Use
Areas, 7th - 1st VI
Closed Markings, 6th-lst, Vol I eds
Chevron Markings, (or Pre-Threshold
Markings), 7th-1st ed, Vol I eds
f) Signs
164
Aerodrome Identification Signs, All
Editions
Aircraft Stand Identification Sign, 8th-
1st, Vol I ed
Category II Holding Position Sign, 6th ed
Category II or III " " ", 7th ed
Information Signs, 8th-lst, Vol I eds
Mandatory Instruction Signs, 8th-lst,
Vol I, eds
Signing Aids, 6th ed
VOR Aerodrome Check-Point Sign, 5th-6th
ed
g) Signalling Devices
Ground Signal Panels Signal Area, All
Editions
h) Markers
Boundary Day Markers, 2nd ed
Boundary Markers, 7th-1st Vol I, eds
Day Markers for Snow-Covered Runways,
3rd-6th eds
Day Marking, 2nd ed (Marker form)
Edge Markers for Snow-Covered Runways,
7th-lst Vol I, eds
Stopway Day Markers, 4th-6th eds
Stopway Edge Markers, 7th-lst Vol I, eds
Systems of Approach Day Markers, 3rd ed
Taxiway Edge Markers, 8th-lst ed, Vol I
Unpaved Runway Edge Markers, 7th-lst ed,
Vol I
Unpaved Taxi Edge Markers, 7th ed
Unserviceability Markers, 6th-1st, Vol I,
eds (Cones, Flags, Markers)
VOR Aerodrome Check-Point Markers, 5th ed
i) Approach Day Marking System
165
1st, 2nd 3rd editions
(Takes form of markers rather than
markings;
title includes Markers not Markings for
3rd ed)
iv Radio Aids
a) Aids to Final Approach Landing
Instrument Landing Systems (ILS),
All Editions
Localizer
Glide Path
Marker Beacons
"Pre-edition", 1949 to 6th ed, 1960 eds
Locator
Microwave Landing System (MLS), 4th ed,
Vol I, 1985
b) Short Distance Aids
VOR, All Editions
DME, All Editions
(4th ed, Vol I, has DME/N, DME/W, DME/P)
c) Radio Beacons
NDB, 2nd to 4th, Vol I eds,
En route Marker Beacons, 2nd-4th, Vol I eds
d) Long Distance Aids
Loran, lst-1st, Vol,  I eds
Loran-A, 2nd Vol I-4th, Vol eds
Consul, 5th edition to present
e) Other Aids (Listed in Attachment A)
166
Short Range Aids (2nd ed to present):
VHF Multi-Track Range
GEE System
Long Range (6th ed to at least 1st, Vol I
ed) :
Dectra
Delrac
Navaglobe-Navarho
167

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190
GENERAL INDEX
Aeronautical Navigation Aids: ICAO, importance
to aero aids, 4; International character of
aero aids, 3, 4; Messages, 13; Methodology, 1,
5; Nature of, 1, 2, 3, 14, 15; Physical
Properties,9-14; Semiotics, 10-14; Statistics,
5-9; Terminology, viii, 1, 2, 9; Unified
Subject, viii.
See Also: Radio Aids and Visuals Aids,
Classification, History, Messages.
Classification, viii;  Main: introduction, 49-51;
Classification, 51-54; Explanatory notes, 54-59
(all-lighted, 55-55, partially-lighted, 55-58,
special dual classification, 58, unlighted,
58-59; radio aids, 59). Variant: Classifi-
cation, 60-63; Explanatory notes, 63-71
(approach lighting, 63-65, final approach,
65-68, runway taxiway, 68-69, obstruction,
69-71, beacon, 71.
SEE ALSO: Illustrations.
History, viii.  Introducation Early Aviation,
16-17. Early Nav Aids: 20-31 (Aerial Light-
houses, 24-25; Boundary Lights, 20-22;
Messages, 20-23; Obstruction Lights, 22;
Beacons, 23-26; Wind Indicators, 26; Signs 
Markings, 26-27; Acoustic Signal, 28; Radio
Aids, 27-31). 1938-1943 Developments: 32-36
(Boundary, Runway Taxiway, Strip, Range,
Threshold Lights, 32-33; Taxiway Light, 33;
Approach Lights, 33-34; Fixed Approach Lights,
34; Runway Lights 34-35; Beacons, 35; Radio
Aids, 35-37). 1944-1950 Developments: 37-48
(Approach Lights, 37-40; Runway Lights, 40-41;
Threshold TDZ, 41; Radio Aids, 41-42;
International Cooperation, 41-44). Epilogue:
Approach Lighting, 44-48.
Illustrations, 72-77; Explanatory Notes, 78-83.
Messages, Production of, 13; Nature of, 14-15;
191
Forms of, 13.
SEE ALSO: Visual Aids and Radio Aids.
Physical Properties, 9-14.
Radio Aids (Electronic Aero Aids), vii. Over-
view and changes, 139-142; ILS, 142-145
(Purpose, 142-143, Localizer, 143, Glide Slope,
143-144, Marker Beacon, 144-145, Locator,
145). MLS, 145-147. Beacons, 151-153. Consul,
Loran Satellite Navigation, 153-155. VOR,
DME, TACAN, VORTAC, 148-151. Peripheral
Aids, 156-158 (Delrac Dectra, 156-157;
Navaglobe Navrho, 156, 157-158, GEE, 
VHF Multi-track Pulse Range, 158).
Semiotics, vii, 9-14.
Transportation Markings, General, vii, 10, 12.
Other Modes: Marine Aids to Navigation, vii, 1,
4, 12, 13, 15, 24, 25, 50, 57, 93, 112, 113,
121, 132, 134; Railway Signs Signals, vii, 1,
4,5, 12, 14, 15, 49, 131; Traffic Control
Devices, vii, 1, 4, 15, 58, 81, 131.
Visual Aids, Lighted: vii, viii. Approach
Lighting, 85-91 (Introduction, 85-87;
Equipment, 87-89; Messages, 89-91). Final
Approach Indicators, 92-100 (Introduction, 92-
93, Messages, 93-99; Equipment, 99-100). Runway
Taxiway Lights, 101-111 (Background,
Terminology and Functions, 101-102; Inset
Lights, 102-105; Elevated Lights, 105-107;
Messages, 107-111). Beacons Obstruction
Lighting, 112-119 (Introduction, 112-113;
Beacon Equipment,113-115; Obstruction Lighting
Equipment, 115-118; Beacon Obstruction
Messages, 118-119).
Visual Aids, Partially-Lighted Unlighted:
Introduction, 121-123; Sign Types Messages,
123-124; Marking Types Messages, 124-128
(Runway-related, 124-127; Taxiway-related, 127-
128); Indicators, 129-130; Marker Types 
Messages, 130-134; Obstruction Marking Types 
Messages, 134-136; Restricted Use Area Visual
Aids, 136-137.
192
GENERAL INDEX
Aeronautical Navigation Aids: ICAO, importance
to aero aids, 4; International character of
aero aids, 3, 4; Messages, 13; Methodology, 1,
5; Nature of, 1, 2, 3, 14, 15; Physical
Properties,9-14; Semiotics, 10-14; Statistics,
5-9; Terminology, viii,  1, 2, 9; Unified
Subject, viii.
See Also: Radio Aids and Visuals Aids,
Classification, History, Messages.
Classification, viii;  Main: introduction, 49-51;
Classification, 51-54; Explanatory notes, 54-59
(all-lighted, 55-55, partially-lighted, 55-58,
special dual classification, 58, unlighted,
58-59; radio aids, 59). Variant: Classifi-
cation, 60-63; Explanatory notes, 63-71
(approach lighting, 63-65, final approach,
65-68, runway taxiway, 68-69, obstruction,
69-71, beacon, 71.
SEE ALSO: Illustrations.
History, viii. Introducation Early Aviation,
16-17. Early Nav Aids: 20-31 (Aerial Light-
houses, 24-25; Boundary Lights, 20-22;
Messages, 20-23; Obstruction Lights, 22;
Beacons, 23-26; Wind Indicators, 26; Signs 
Markings, 26-27; Acoustic Signal, 28; Radio
Aids, 27-31). 1938-1943 Developments: 32-36
(Boundary, Runway Taxiway, Strip, Range,
Threshold Lights, 32-33; Taxiway Light, 33;
Approach Lights, 33-34; Fixed Approach Lights,
34; Runway Lights 34-35; Beacons,  35; Radio
Aids, 35-37). 1944-1950 Developments: 37-48
(Approach Lights, 37-40; Runway Lights, 40-41;
Threshold TDZ, 41; Radio Aids, 41-42;
International Cooperation, 41-44). Epilogue:
Approach Lighting, 44-48.
Illustrations, 72-77; Explanatory Notes, 78-83.
Messages, Production of, 13; Nature of, 14-15;
191
Forms of, 13.
SEE ALSO: Visual Aids and Radio Aids.
Physical Properties, 9-14.
Radio Aids (Electronic Aero Aids), vii. Over-
view and changes, 139-142; ILS, 142-145
(Purpose, 142-143, Localizer, 143, Glide Slope,
143-144, Marker Beacon, 144-145, Locator,
145). MLS, 145-147. Beacons, 151-153. Consul,
Loran Satellite Navigation,  153-155. VOR,
DME, TACAN, VORTAC, 148-151. Peripheral
Aids, 156-158 (Delrac Dectra,  156-157;
Navaglobe Navrho, 156,  157-158, GEE, 
VHF Multi-track Pulse Range, 158).
Semiotics, vii, 9-14.
Transportation Markings, General, vii, 10, 12.
Other Modes: Marine Aids to Navigation, vii, 1,
4, 12, 13, 15, 24, 25, 50, 57,  93, 112, 113,
121, 132, 134; Railway Signs Signals,  vii, 1,
4,5, 12, 14, 15, 49, 131; Traffic Control
Devices, vii, 1, 4, 15, 58, 81,  131.
Visual Aids, Lighted: vii, viii.  Approach
Lighting, 85-91  (Introduction, 85-87;
Equipment, 87-89; Messages, 89-91). Final
Approach Indicators, 92-100  (Introduction, 92-
93, Messages, 93-99; Equipment, 99-100). Runway
Taxiway Lights, 101-111 (Background,
Terminology and Functions,  101-102; Inset
Lights, 102-105; Elevated Lights, 105-107;
Messages, 107-111). Beacons Obstruction
Lighting, 112-119 (Introduction, 112-113;
Beacon Equipment,113-115; Obstruction Lighting
Equipment,  115-118; Beacon Obstruction
Messages,  118-119).
Visual Aids, Partially-Lighted Unlighted:
Introduction, 121-123; Sign Types Messages,
123-124; Marking Types Messages, 124-128
(Runway-related, 124-127; Taxiway-related, 127-
128); Indicators, 129-130; Marker Types 
Messages, 130-134; Obstruction Marking Types 
Messages, 134-136; Restricted Use Area Visual
Aids, 136-137.
192
INDEX OF AERO NAVIGATION AID PHENOMENA
AAI, xii, 68.
Aerial Lighthouses, 18, 24, 25.
Aerial Lighting, 24.
Aero Aids, vii, 1, 3, 5, 12, 13, 14, 16, 17, 18,
28, 37, 50, 78, 93, 122, 129, 134, 141, 159.
Aero Identification Signs, 124.
Aero Lights/-ing, 16, 20, 23, 50, 55, 64, 85,
106, 113.
Aerodrome Beacons, 25, 52, 113, 115, 145, 162.
Aerodrome Lighting Marking, 2.
Aero Markers, 131.
Aero Markings, 26.
Aero Navigational/-al Aids, 1, 2, 4, 10, 12,
13, 15, 16, 20, 32, 43, 50, 84, 98, 103, 107,
121, 140, 143, 159.
Aero Signs, 27.
Aerodrome Beacons, 26, 56.
Aerodrome Identification Signs, 52, 81, 112,
148, 165.
Aids, 3, 13, 14, 28, 29, 31, 35, 45, 50, 55, 58,
59, 129, 134, 140, 141, 142, 153, 156.
Aids for Restricted Areas, 160.
Aids to Final Approach Landing (Radio), 166.
Air Markers, 27.
Aircraft Markings, 53.
Aircraft Stand Identification Signs, 52, 124,
148, 165.
Aircraft Stand Maneuvering Guidance Lights, 109,
110.
Aircraft Stand Markings, 127, 128, 163.
Airfield Aids, viii.
Airfield Lighting Marking, 2.
Airfield Lights/-ing, 2.
Airport Aids, viii, 55.
Airport Ground Lighting, 2.
Airport Identification Beacon, 67, 103.
Airport Lights(-ing), 1, 32, 55, 101, 102, 112.
Airway Beacons, 20, 24, 27, 28, 33.
Airway Lighting, 24.
193
ALSF-I, ALSF-II, xii, 61.
AOE, xii, 62, 63, 94, 98.
Angled Approach Lights, 38.
Angle-of-Approach Lights, 160, 161.
APAPI, xii, 61, 66, 97, 99, 144, 160.
Approach Aids, 13.
Approach Day Markers, 162.
Approach Day Marker System, 162, 165, 166.
Approach (Radio) Aids, 28.
Approach Lighting, 14, 21, 33, 34, 37 38,
45, 46, 48, 51, 54, 56, 60, 63, 65, 72,
80, 84, 85, 86, 87, 89, 90, 105, 107, 111,
160, 161.
Approach Lighting System Type "A", 160.
Approach Lighting System for Runways with
Neither Stopways nor Displaced Thresholds,
160.
Approach Lighting System with Displaced
Threshold, 160.
Approach Lighting System with Stopway, 160.
Approach Slope Indicator Systems, 98.
Apron Safety Lines, 53, 128.
ASMGL, 145.
AT-VASIS, xii, 61, 67, 95, 160.
Auxilliary Beacon, 23, 24.
AVASIS, xii, 61, 66, 95, 160.
Aviation Aids, 3.
Aviation Aids Lighting, 2.
Azimuth Station, 54.
Back Course Beacon,145.
Balisor Lamp, 116.
Barrettes, 65, 86.
Bartow Light, 34, 36, 38.
Beacons, 22, 23, 24,
56, 62, 70, 71, 78,
116, 118, 140, 145,
Blister Lights,
Border Lights, 20.
Boundary Day Markings, 146.
Boundary Lights, 20, 21, 22, 27, 32, 33, 34.
25, 29, 35, 36, 52, 55,
80,
151,
101,
162.
112, 113, 114,
194
35, 101, 111, 162.
Boundary Markers, 53, 81, 133, 134, 165.
Calvert Light(s), 39.
Capacitator Discharge Light, 51, 54, 84, 85, 88,
89, 114, 116.
Category II Holding Position Signs, 165.
Category II/III Holding Position Markings, 164.
Category II/III Holding Position Signs, 123,
165.
Caution Bars,
Centerline Lights, 36, 37, 39, 44, 45, 46, 51,
101.
CHAPI, xii, 61, 66.
Chevron Markings, 164.
Circle Markers, 27.
Clearance Bars, 15,  52, 93, 101, 109, 161, 164.
Closed Markings, 136, 148, 164.
Closed Runway Aids, 136.
Closed Taxiway Aids, 136.
Code Beacon, 23, 56, 80, 114, 116, 118.
Colors, 164.
Compass Locator, 82, 143, 145, 152.
Condenser Discharge Light, 39.
Cone Markers, 153, 165.
Consul, 54, 59, 149,  153, 154, 156, 166.
Contact Lights, 34.
Course Light, 23.
Course Setter, 30.
Crossbar Lights, 42.
Day Aid, 127.
Day Markers, 134.
Day Markers for Snow-Covered
Runways,  163.
Day Marking (Aero) Marker, 165.
Day Marking Aids, 163.
Day Marking -- Landing Aids, 163.
Day Marking (Marker Form), 165.
Day Marking (Markers) of Snow-
Covered Runways, 163.
195
Day Marking of Snow-Covered Runways,
163.
Day Marking -- Taxying Aids, 164.
DBGA, xii, 68.
DECCA, 157.
DECTRA, 156, 157, 167..
DELAC, 156, 167.
Differential GPS (DGPS), 156.
Directional Arrows, 27.
Directional Beacon, 30, 151.
Directive Beacon, 30.
Discharge Light,
Displaced Runway Threshold Markings, 163.
Displaced Threshold Markings, 163.
Distance Arrows, 27.
Distance-to-go Markings, 163.
DME, 39, 54, 141, 142, 143, 148, 149, 150, 151,
166.
DME/P, 147, 149, 166.
DME/N, 147, 149, 166.
DME/W,
DVOR,
147,
151.
149, 166.
Edge Lights, 51.
Edge Markers for Snow-Covered Runways, 165.
Electronic Aero Navigation Aids, 139.
Electronic Aids, 1, 59, 82, 139.
Electronic Navigation Aids, 53, 59,  77.
Elevated Lights, 62, 68, 80, 101, 105, 106,
107.
Elevation Station, 54.
End Lights, 51.
En-route VHF Marker Beacon, 54, 55, 149, 166.
Exit Taxiway Center Line Lights on High Speed
Exit Taxiways, 161.
Exit Taxiways Center Line Lights on Other
Exit Taxiway, 161.
Fan Markers, 153.
Final Approach Glide Slope Indicator, 34.
Final Approach Indicators, 51, 57, 65,
196
68, 85.
Final Approach Lights, 54, 56, 60, 61, 72, 81,
92, 93, 99, 111, 112, 160.
Fixed Distance Lights, 161.
Fixed Distance Markings, 53, 126.
Fixed Lights, 87, 90, 100.
Flag Markers, 53, 59, 122, 135, 136, 164,
165.
Flashing Beacon, 25.
Flashing (Strobe) Lights, 37, 47, 60, 63, 66,
80, 85, 86, 87, 88, 89, 90.
FLOS, xii, 68, 94.
Fresnel Beacon, 115, 116.
Fresnel Obstruction Beacon, 114.
Fully-Lighted Aids, 57.
GAIL, xii, 67.
GEE System, 158, 167.
Glide Slope, 142, 143, 144, 166.
Glide Path Indicator, xii,  30, 36, 53, 61, 66,
149.
GLISSADA, 67, 94.
GLONASS, 129, 154.
GNSS, 129, 142, 154.
GPS, 129, 154, 155.
Ground Aids, viii, 2, 54.
Ground-based Aids, 2.
Ground Signal Panel, 165.
Guidance Aids, 28, 29.
GVDI, xii, 68.
GPI, 68, 98.
GVGI, xii.
HAPI, xii, 67, 160.
HAPI-PLASI, 51, 55, 61,  67, 68.
H-PAPI, 61, 66, 97.
Hazard Beacon, 24, 114, 162.
Helicopter Approach Lights, 161.
Heli-Plasi, 55, 61, 67.
Helicopter Final Approach Takeoff Area Lights
(edge), 52.
197
Helicopter Touchdown Landing Area Lighting
Systems (edge), 52.
Helideck Markings, 53.
Heliport Air Taxiway Markings, 53.
Heliport Beacon, 52, 56, 113.
Heliport FATO Markings/Markers, 53.
Heliport Identification Markings, 53.
Heliport Lights, 111.
Heliport Markings Markers, 53, 59, 111.
Heliport Mass  Markings, 53.
Heliport Name Markings, 53.
Heliport Taxiway Markings, 53.
Heliport TD Markings, 53.
High Intensity Beacon, 58, 67.
High Intensity Lights, 87.
High Intensity Obstruction Light, 52, 56, 115
118, 119.
High Intensity Runway Edge Lights, 97.
High Intensity Unidirectional Elevated Lamp/
Lights, 51, 60.
High Intensity Unidirectional Lamp, 56.
Holding Position Light, 52, 101, 106, 123.
Identification Beacon, 52, 111, 113, 114, 115,
116, 118, 162.
Identification Markings,111.
Illuminated Non-Illuminated Signs,
ILS, 30, 36, 39, 41, 49, 53, 59, 82,
142, 143, 144, 146, 147, 151, 152,
52.
140,
153,
141,
166.
ILS Locators, 141.
Identification of Stand, 115.
Independent Aids, 53, 59, 148.
Inner (Marker) Beacon, 144, 145.
Information Signs, 52, 81, 124, 165.
Indicators, 34, 52, 53, 57, 62, 65, 68, 92, 122,
129, 162.
Inpavement Lights, 55, 57, 109.
Inset Lights, 55, 57, 74, 78, 88, 101, 102, 104,
105, 107.
Landing Aid Lights, 101.
198
Landing Aids, 55.
Landing Aerodromes without Runway Day Marking,
163.
Landing Direction Indicators, 52, 57, 81, 162.
Landing Direction Lights, 111.
Lead-in-Lighting System for Runways with Neither
Stopways nor Displaced Thresholds, 161.
Lead-in-Lights, 88, 161.
Lead-in-Line, 115.
Lead-out-Line, 115, 116.
Light Bar, 65, 86.
Lighted Aero Aids, 85.
Lighted Aero Nay Aids, 85.
Lighted Aids, 14, 121, 131, 134, 139, 159.
Lighted Airway, 18.
Lighted Precision Descent Indicators, 129.
Lighted Signs, 51.
Lights/-ing, 20, 21, 26, 32, 33, 50, 55,  63, 64,
68, 85, 89, 90, 91, 92,  101, 102, 104, 110, 111,
112, 115, 118, 119, 166.
Locator, 143, 149, 166.
Localizer, 30, 53, 142, 143, 144, 149, 166.
Long Distance Aids, 166.
Loran, 140, 149, 153, 166.
Loran-A, 53, 59, 149, 154, 166.
Loran-C, 142, 154.
Low Intensity Edge Light, 97.
Low Intensity Light, 31.
Low Intensity Obstruction Light, 52, 56, 62, 63,
70, 115, 119,  146, 162.
Low Intensity Omnidirectional Light, 60.
Low Powered Fan Markers, 153.
MALSF, xii, 61.
MALSR, 61.
Mandatory Instruction Signs, 52, 81, 123, 165.
Marker Beacon, 30, 35, 53,  82, 144, 145, 149,
153, 166.
Marker Boards, 137.
Marker Lights, 34.
Markers, 27, 33, 50, 53, 58, 76, 81, 122, 129,
199
130, 131, 132, 134, 136, 137, 146, 147, 162,
164, 165, 166.
Markers (Radio), 139.
Marking Aids, 146.
Marking of Snow-Covered Runways, 147.
Markings, 14, 27, 49, 53, 58, 63, 76, 81, 102,
110, 119, 122, 123, 124, 131, 134, 137, 162,
166.
Markings (Non-sign), 54, 77.
MDLA, xii, 68, 94.
Medium Intensity Approach Lighting, 84, 87.
Medium Intensity Beacon, 71.
Medium Intensity Obstruction Lighting, 56, 62,
63, 69, 70, 79, 80, 115, 117, 119, 162.
Medium Intensity Omnidirectional Lighting, 60.
Medium Intensity Omnidirectional Elevated
Light/-ing, 51.
Medium Intensity Runway Edge Lights, 49.
Medium Intensity Unidirectional Approach Lights,
87.
Middle Locator, 145.
Middle Marker Beacon, 145.
Mini-PAPI, 98.
MLS, 58, 59, 82, 140, 142, 145, 146, 147, 151,
155, 166.
Multi-mode Radio Aids, 140, 151.
Navaglobe-Navarho, 156, 157, 158, 167.
Navigation/-al Aids, viii, 1, 2, 3, 28, 42, 49,
111, 139, 140.
NDB, 28, 54, 59, 139, 141, 142, 145, 149, 151,
152, 166.
Neon Discharge Lamp, 115.
Neon Obstruction Lights, 66.
No Entry Signs, 81, 123.
Non-Obstruction Aids, 159.
Non-load Bearing Surface Aids, 136, 137.
Non-load Bearing Surface Markings, 137.
Non-sign Markings, 58, 131, 134.
Obstacle Lighting, 86, 101, 112.
200
Obstruction Aids, 13, 143, 159.
Obstruction Beacons, 101, 105.
Obstruction Colors, 147.
Obstruction Flags, 147.
Obstruction Light/-ing, 21, 22, 52, 56, 62, 70,
73, 79, 112, 113, 114, 115, 116, 117, 118, 164.
Obstruction Markers, 147.
Obstruction Markings, 53, 59, 76, 81, 113, 121,
123, 129, 131, 134, 135, 164.
ODALS, 61.
OMEGA, 140, 142.
Omnidirectional Flashing Lamps/Lights, 60, 86.
Omnidirectional Lighting, 89, 112.
Omnidirectional Medium Intensity Lights, 54.
Omnidirectional Simplified Approach Lighting,
80.
Optical Localizer, 100.
Optical Projector Ground Aids, 68.
Outer Localizer, 133.
Outer Marker Beacon, 144, 145.
PAPI, xii, 34, 61, 66, 67, 81, 94, 97, 99, 160.
Parking Aid, 52.
Parking Docking Systems, 102.
Parking Lights, 102.
Partly Integrated Aids, 51, 54, 59, 148.
Partially Integrated Systems, 128.
Partially Lighted Aids, 54, 57, 123.
Patterns, 53, 135, 164.
Paved Day Markings, 163.
Paved Runway Day Markings, 163.
Paved Runway Markings, 163.
Paved Taxiway (Day) Markings, 164.
Pavement Markings, 14, 15, 27, 50, 134.
PCOLA, xii, 64.
P-DME, 147.
Perimeter Lights, 111.
PLASI, xii, 55, 68, 81, 93, 94, 98, 100.
Point-Source Aids, 140.
POMOLA, xii, 68.
Precision Approach Category I Lighting System,
201
161
Precision Approach Category II Lighting System,
161.
Precision Approach Category II III Lighting
System, 161.
Precision Approach Lighting Systems, 60, 61,
161.
Precision Approach Runway Approach Lighting
System, 144.
Pre-threshold Area Aids, 136.
Pre-threshold Markings, 137, 164.
Pulsed Code Aids, 67.
Pulsed Code Optical Landing Aids, 68.
PVG, xii, 94.
Radio Aids, vii, viii, 9, 16, 18, 28,  35, 41,
59, 139, 144, 149, 152, 159, 166.
Radio Beacons, 29, 149,  166.
Radio Marker Beacons, 28.
Radio Navigation Aids, 1, 2, 29, 42.
Radio Ranges, 29, 30, 39, 41, 148.
RAILS, xii,  60,
Range Beacon, 25.
Range Lights, 21, 32, 36, 162.
Reflective Delineators, 33.
Reflective Markers, 133.
REILS, xii, 60, 64, 85, 89, 107.
Restricted Use Area Markings, 123, 129, 136,
159.
Retroreflective Markers, 133.
RILS, xii, 60, 64.
Rotating (Radio) Beacon, 28, 29.
Routing Beacon, 24.
RT-VASIS, xii, 67, 96.
RTILS, xii, 60,  64, 85, 89,  107.
Runway Taxiway Elevated Lights, 51.
Runway Caution Zone Markings, 163.
Runway Centerline Lights, 108, 161.
Runway Centerline Marking, 53, 125, 163.
Runway Designation Markings, 51, 53, 163.
Runway Edge Lights, 32, 45, 51, 62 64, 68,
69,  83, 101, 102, 106, 161.
202
Runway Edge Markers, 77.
Runway Edge Markings, 163.
Runway Edge/Threshold Lights, 101.
Runway End Lights, 34, 35, 52, 108, 161.
Runway Inset (Inpavement) Lights, 51, 70.
Runway Lights, 20, 32, 34, 38, 40, 41, 55, 62,
64, 69, 74, 92, 101, 102, 106, 161.
Runway Longitudinal Markings, 163.
Runway Markings, 42, 146, 162.
Runway Side Stripe Markings, 53, 126, 163.
Runway Threshold Wing Bar Lights, 161.
Runway Threshold Lights, 51, 108, 161.
Runway Threshold Markings, 163.
Runway TDZ Lights, 109.
R/W VASIS, 93, 94.
Safety Aids, 4.
SAVASIS, xii, 61, 66.
Sequenced Flashing Lights, 91.
Semi-Buried Lights, 57.
Semiflush Lights, 32, 38, 41.
Short Distance Aids, 166.
Short Range Aids, 158.
Side Stripe Markings, 163.
Signage, 26.
Signing Aids, 165.
Signing Devices, 165.
Signs, 14, 15, 50, 52, 58, 76, 81, 102, 122,
123, 131, 162, 164.
Signs Providing Other Information, 124.
Simple Approach Lighting System, 60, 84, 90,
144, 145, 161.
Simplified Type Approach Lighting System, 57.
Slopeline Approach Lighting 36, 38, 39, 40, 45,
66, 94.
Snow-covered Runway Edge Markers, 53, 132.
Sonic Marker Beacon, 28.
Sonne, 153, 154.
Sphere/-ical Markers, 53, 59,  135, 136.
SSALR, SSALSF, xii, 61.
Standard Beam, 30.
203
Stop Bar Lights, 15, 52, 101, 109.
Stop Bar Markings, 147.
Stopway Day Markers, 163, 165.
Stopway Edge Markers, 53, 132, 165.
Stopway Lights, 52, 80, 108, 161.
Strip Lights, 32.
Strobe Lights, 23,  37, 46, 63.
Surface Lights, 53.
Systems of Approach Day Markers, 165.
TACAN, 148, 149, 150, 151.
Taxiway Lights, 93, 94, 95, 96, 97.
Taxiway Centerline (Straight, Curved
Sections; Intersections) Lights, 10, 12, 51,
109, 145, 161.
Taxiway Centerline Markers, 59, 132.
Taxiway Centerline Markings, 53, 111, 127, 164.
Taxiway Day Markings, 164.
Taxiway Edge Lights, 32, 51, 109, 161.
Taxiway Edge Markers, 81, 82, 132, 165.
Taxiway Edge Marking, 53.
Taxiway Guidance Systems, 161, 162, 164.
Taxiway Holding Markings, 115.
Taxiway Holding Position Lights, 75, 80, 161.
Taxiway Holding Position Markings, 53,  127, 164.
Taxiway Inset (Inpavement) Lights, 51, 62.
Taxiway Intersection Marking, 53, 127, 164.
Taxiway Light/-ing, 12, 16, 20, 32, 42, 49, 55,
62, 68, 69, 75, 80, 92, 101, 102, 104, 105,
106, 111, 161.
Taxiway Longitudinal Markings, 147, 164.
Taxiway Markers, 132, 133.
Taxiway Day Markings, 164.
Taxiway Markings, 53, 163.
Taxiway/Runway Intersection Signs, 123.
Taxiway Side Stripe Lines, 137, 164.
Taxiway Side Stripe Markings, 148.
TDZ Lights, xii, 39, 51, 101, 108, 145, 161.
TDZ Markings, 53.
TDZ Zone Markings, 126, 147, 163.
Three-Bar AVASIS, 61, 160.
204
Three-Bar VASIS, 51, 66, 94, 95, 144.
Threshold/End Lights, 49, 62, 69, 106.
Threshold Identification Light, 51.
Threshold Lights, 12, 20, 32, 34, 39, 41, 64,
108.
Threshold Markings, 53, 125, 126, 163.
TLLAS, xii.
T-PASI, xii, 37, 61, 66, 68, 98, 100.
Turning Lanes, 115.
T-VASIS, xiii,  51, 54, 67, 81, 93, 94, 95, 96,
97, 100, 160.
TVG, xiii, 67, 68, 93.
TVOR, 151.
Tri-Color Aids, 66, 98, 100.
Tri-Color VASI, 68, 94.
Type I, Type II (Approach), 61.
Unidirectional Flashing Light, 60.
Unidirectional High Intensity Lights, 54.
Unlighted Aids, 14, 48, 122, 159.
Unlighted Navigation Aids, 52, 121.
Unlighted Obstruction Markings, 113.
Unpaved Edge Markers, 53, 72.
Unpaved Runway Edge Markers, 81, 132, 165.
Unpaved Runway Edge Markings, 165.
Unpaved Runway Day Markings, 163.
Unpaved Runway Markings, 163.
Unpaved Taxiway Day Markers, 164.
Unpaved Taxiway Edge Markers, 53, 165.
Unserviceability Cones, 164.
Unserviceability Flags, 164.
Unserviceability Marker Boards, 164.
Unserviceability Markers, 148.
Unserviceability Markings, 164.
Unserviceable Area Aids, 136, 137.
VAPI, xiii, 67.
VASIS, xiii, 51, 55, 66, 68, 81, 94, 97, 99, 100,
160.
VDGS, 110, 145, 162.
Vertiport Lights, 63, 71, 111.
205
Vertiport Markings, 63, 71, 111.
VGPI, 68, xiii.
VHF Multi-Track Pulse Rnage, 158, 167.
VHF Multi-Track Range, 149.
Visual Aids, vii, viii, 5, 9, 16, 20, 28, 42,
47, 146, 159, 160, 162.
Visual Aids for Denoting Obstacles, 134.
Visual Aids for Denoting Restricted Use Areas,
136, 164.
Visual Aids for Navigation, 1, 159.
Visual Docking Guidance System, 52, 110, 111.
Visual Navigation Aids, 2.
Visual Parking Docking Guidance, 109.
VOR, 30, 35, 41, 53, 82, 141, 142, 148, 149,
150, 166.
VOR Aerodrome Check Point Markers, 81, 125,
165.
VOR Aerodrome Check Point Markings, 124, 127,
148,  163.
VOR Aerodrome Check Point Signs, 81, 124, 165.
VOR/DME, 139, 141, 150, 154.
VORTAC, 148, 150, 151.
Water Aerodrome Aids to Taxying, 164.
Water Aerodrome Day Markings, 163.
Water Aerodrome Day Marking Landing Aids, 163.
Winching Area Markings, 53.
Wind Cones, 26, 81, 82, 111, 129, 130.
Wind Direction Indicators, 129, 162.
Wind Indicators, 26, 52, 57.
Wind Socks, 129.
Wind Tee, 26, 34,  82, 129, 130.
Wireless Lighthouse 29.
Xenon Discharge Light, 83.
Z Markers, 153.
206
INDEX OF NAMES:
GEOGRAPHICAL, POLITICAL, PERSONAL, CORPORATE,
ORGANIZATIONS, GOVERNMENT AGENCIES
ADB, ix, 2, 54, 76, 79, 80, 81, 82, 88, 89, 104,
106, 113, 115, 130, 132, 133.
Adock, 31.
Aeronautical Board, 40.
Aeronautical Research Labs, x.
Africa, 7, 8.
AGA, 25, 40.
Air Afrique, 8.
Air Flo, xi.
Air France, 18.
Air University Library, ix.
Alaska, 34.
ALPA, 38, 39, 40, 41.
Ameriel, ix.
Antonenka, 34, 92.
Arcata, 38, 39.
Argentina, 8.
Army/Air Force/Navy/Civil Landing Aids
Experiment Station, 33, 40.
Ashford and Wright, 71, 111.
Atlantic, 17.
ATA, 40, 45.
Australia, x, 7, 8, 18, 19, 25, 32, 35, 67,
93.
Aviation Committee, 42.
Bahrein, 8.
Barthes, 10.
Bartow, 34, 40.
Belgium, x, 7, 19, 151.
Bellini-Tosci, 30.
Benin, 8.
Black, 20, 23, 25, 26.
Blacklock, 155, 156.
207
Boughton, 25.
Brazil, 7, 8.
Breckinridge, 24, 34, 35, 41, 91.
British Empire Commonwealth, 19.
Buck, 1.
Burkina-Faso, 8.
Buttersworth-Hayes, 142, 146.
CAA, U.S., x, 34, 39, 40, 41, 45, 46, 47,
114.
CAB, U.S., x, 6, 40.
Caldwell, 25.
California, 18, 46.
Calvert, 39, 44.
Canada, x, 7, 8, 19, 142, 152, 155.
Cegelec, ix, 2, 20, 67, 70, 80, 81, 98, 104,
105, 114.
Central Africa, 19.
Central African Republic, 8.
Chad, 8.
Cheyenne, 18.
Chicago, 18.
Chicago-New York, 29.
China, 7, 8.
Christian, 47.
Clark, x, 34, 92, 93, 94.
Clausing, 148, 149, 152, 155.
Colombia, 8.
Condom, Pierre, 59.
Congo, 8, 19.
Cook, 66.
Crouse-Hinds, ix, 2, 67, 78, 79, 105,
106, 114, 116, 130.
Danaid, ix, 62, 67, 81, 98, 99, 100,
129.
Davies, 19.
Denmark, x, 7, 151.
Devote, ix, 55, 67, 98, 100.
Dijon, 25.
Douglas, 16, 33.
Duke, 20, 21, 26.
208
Dutch East Indies, 17, 18.
East Asia, 19.
EG, ix, 8081, 117, 118.
Elfaka, 47.
ESNA, ix.
Ethiopia, 8.
Eurocontrol, x.
Europe (-an) ,4, 18,
116, 153.
19, 24, 25, 26, 27, 30,
Europe ICAO, 42, 43.
FAA, x, i, 2, 5, 24, 48, 49, 55, 68, 69, 70,
82, 85, 87, 88, 89,
130, 132, 136, 151,
91, 107,
152.
108, 112, 114,
FANS, 129, 130.
Field, 2.
Finch, 18, 19, 20.
Follett, 19.
France, x, 7, 8, 45, 151.
French Indo-China, 19.
French Polynesia, 8.
Fresnel, 4, 70, 116, 117.
General Electric,  ix,  28, 47.
Germany, x, 7, 8, 30, 153.
Gibbs-Smith, 17.
Givon, 11.
Glidden, 34.
Glines, 142.
Godfrey Engineering,  ix,  80, 89, 106.
Goldstrom, 25.
Gordon,  34, 92, 93, 94.
GP Systems, 155,
Greece, 8.
Greif, 27.
Grover, 30, 148, 153, 157, 158.
Gulf States, 7.
Hall, 1, 30.
Harper, 18, 22, 25.
Harvey, 27.
History of  Air Navigation Group, 16.
Hobbs, 141, 156.
209
Hounslow, 26.
Hudson, 42.
Hughey Philips, ix.
Humboldt County Library, ix.
IATA, 39, 141.
Idelwild Airport, 46.
Idman, ix, 2, 54, 78, 79, 81, 105.
Illuminating Engineering Society,  x,
47, 48.
Imperial Airways, 18.
India, 7, 8, 18.
Indianapolis, 34, 38.
Indonesia, 7, 8.
Inter-Allied Aviation Commission, 42.
International Air Convention, 42.
International Civil Aviation Organization
44, 45, 46, 49, 54, 56, 57, 59, 60, 63, 64, 65,
66,
100,
113,
129,
143,
67,
102,
114,
132,
147,
68, 69,
104,
115,
133,
148,
79,
105,
119,
134,
151,
82,
107,
121,
136,
153,
89,
108,
123,
137,
154,
91, 94,
109,
124,
140,
157,
96,
110,
125,
141,
158,
98,
112,
126,
142,
159.
99,
International Commission for Air Navigation
(ICAN), 42, 43.
International Hydrographic Bureau (IHB), 154,
157.
International Telephone Development Co., 36.
Israel, 7.
Italy, 7, 8.
ITT Avionics, xi.
ITTE, 57.
Ivory Coast, 8.
Jaquith Industries, xi.
Japan, 7, 8.
Kayton, 30, 36.
Kendall, 29, 30, 31, 35, 36.
KLM, 17.
Knoxville, 46.
Komons, 23, 29.
210
46, 47.
.
Kroger, 34, 38, 41.
Lans, Hoken, 155.
Laughton, 116.
Library of Congress, ix.
Lindsey, 87.
Line Material, 40, 41.
Lockheed Electric, 47.
Lorenz Co., 29.
Luxembourg, ix.
McGhee-Tyson AFB, 46.
McKinleyville, CA., 39.
Madasgar, 8.
Malayasia, 7, 8.
Mannairco, ix.
March AFB, 43,
Mauritania, 8.
Mexico, x, 7,
Ministry of Defense (MOD), U.K, x.
Moore, 38.
Morse, 24, 30, 118, 143, 144, 145, 149,
152, 153.
Mount Angel Abbey Library, ix.
Mueller, 16.
Multi-Electric, ix, 81, 89, 99, 117.
Nantucket, 33.
National Archives, x.
NATO, ix, xi, 2, 49, 57, 60, 61, 63,
65, 68, 80,  87, 112, 151.
Nautel, ix.
NBS, 16, 33.
Netherlands, 7, 47.
8.
New York, 18.
Niger, 8.
North America, 27,
156
North Carolina, 17.
Norvell, ix, 7, 8, 151.
Norway, x, 7, 8, 151.
Oea, 22, 26.
64,
116.
211
Ohio, 18.
Olsen, 139, 140, 141, 142, 146, 150, 155.
Oman, 7.
Omnipol/Tesla, ix, 104.
Oregon State University Library, ix.
Pacific, 19.
Page, David, x, 16.
Pakistan, 7.
Papua New Guinea, 8.
Paris, 42.
Paris-Algiers, 25.
Paris Peace Conference, 42.
Parnell, 28, 35.
Patuxent Naval Air Station, 45.
Philippines, 7, 8.
Philips, 106.
Pollock, 57, 106, 133.
Portland State University Library, ix.
Provisional ICAO (PICAO), xi,  17, 43, 44.
Qatar, 7.
RAE, 2, 44.
Robson, 47.
Royal Air Force, 34.
Royal Institute of Navigatin, x, 16.
Russia, 67, 141, 154.
Russian Federation, 7.
SAS, 7.
St. Exupery, 18.
St  John Spriggs, 20, 22.
Saudia Arabia, 7.
Scandinavia, 7.
Scheller, 29.
Senegal, 8.
Sessions, 16.
Siemens, ix.
Singapore, x, 7.
Slo-Idman, 50.
Smith, H.L., 43.
South Africa, 8, 19.
South America, 18, 19.
212
South Korea, 7.
Soviet Union, 7.
Spain, 7, 8.
Sweden, 7, 8, 133.
Switzerland, x, 7, 151.
Sylvania, 40, 47.
Taiwan, x, 151.
Taneja, 17.
Telefunken,  48.
Tesla, 80.
Thailand, 7.
Thorn Europhane, ix, 54, 78, 80, 97, 105,
113, 114, 129.
Togo, 8.
Toshiba, ix, 116.
Tull Aviation,  ix,  83.
Turner, 145, 146.
TWR, ix.
Ulmer Aeronautique, ix, 57.
Underwood, 154.
United Arab Emirates, 7.
United Kingdom, x, 7, 8, 30, 37, 39, 43, 44,
45, 47.
United Nations, 4, 5.
Unitron International Systems,  xi.
University of California, Berkeley, Libraries,
ix
University of California, Davis, Libraries,
University of Oregon Libraries, ix.
ix.
U.S., x, 2, 4, 5, 7, 8, 11, 18, 19, 20, 24, 25,
26, 29, 30, 31, 33, 35, 37, 38, 41, 44, 45, 46,
47, 55, 56, 57, 61, 63, 64, 65, 66, 68, 69, 78,
79, 87, 88, 89, 91, 94, 114, 115, 132, 142,
143,
U.S.
U.S.
145, 148, 150,
Air Force, 40,
Army, 18, 29.
151,
45,
154,
46, 47.
157.
U.S. Commerce Dept., 20.
USDOD, x, 155.
USDOT, x, 155.
U.S. Lighthouse Bureau, Airways Division, 24.
213
U. S. Navy, 2, 33, 40, 45.
U.S.
USSR,
Post Office,
8.
18, 29.
Valerian, 25.
Valley Illuminators, xi.
Venezuela, 8.
Warner, 17, 18.
Westinghouse Electric, ix, 26, 39, 80.
Whitnah, 21.
Wilcox, ix, 1, 156.
Wilson, 31, 36, 38, 41.
Wood, 20, 21, 34.
World War I, 17, 30.
World War II, 19, 27, 36.
Yaounde Treaty States, 8.
Young, 27.
214
COLOPHON
This book was prepared on an Apple III computer
using Three Easy Pieces software. Drafts and
other materials were printed on an Apple daisy
wheel printer with Prestige Elite 12 type.
Manuscript preparation was augmented by an IBM
Seletric II typewriter with Courier 10 type.
The "printing masters" were prepared on an Apple
Laserwriter II printer with Courier 12 type.
This required the assistance of a Macintosh LC
computer which incorporated the "brains" of an
Apple Iie computer and an updated version of
Appleworks software (which is closely related to
Three Easy Pieces). Br Justin Hertz, computer
director for Mount Angel Seminary, and an
Appletalk network completed the preparations.
Portions of the printing masters were composed
on the aforementioned IBM Selectric II
typewriter.
The pages were printed on a Canon NP 6650 copier
augmented by a Canon NP 4050 copier.
The cover was printed on Cross Pointe 80 pound
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pumice. The book was printed on Cross Pointe 60
pound Bellbrook Laid Text in Oxford cream.
Covers were typeset and printed by the
Benedictine Press. The monograph was bound at
Your Town Press in Salem.