NATIONAL BUREAU OF STANDARDS REPORT

9964

DEVELOPMENT, TESTING, AND EVALUATION OF VISUAL LANDING AIDS

Consolidated Progress Report

For the Period

July 1 to September 30, 1968

By

Photometry Section

Metrology Division

Institute for Basic Standards

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 was established by an act of Congress March 3, 1901. Today, in addition to serving as the Nation’s central measurement laboratory,

the Bureau is a principal focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To this end the Bureau conducts research and

provides central national services in three broad program areas and provides central national services in a fourth. These are: (1) basic measurements and standards,

(2) materials measurements and standards, (3) technological measurements and

standards, and (4) transfer of technology.

The Bureau comprises the Institute for Basic Standards, the Institute for Materials

Research, the Institute for Applied Technology, and the Center for Radiation Research.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the

United States of a complete and consistent system of physical measurement, coor- dinates that system with the measurement systems of other nations, and furnishes

essential services leading to accurate and uniform physical measurements throughout

the Nation’s scientific community, industry, and commerce. The Institute consists

of an Office of Standard Reference Data and a group of divisions organized by the

following areas of science and engineering

:

Applied Mathematics—Electricity—Metrology—Mechanics—Heat—Atomic Physics—Cryogenics2—Radio Physics2 —Radio Engineering2—Astrophysics2—Time

and Frequency.2 THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to methods, standards of measurement, and data needed by industry, commerce,

educational institutions, and government. The Institute also provides advisory and

research services to other government agencies. The Institute consists of an Office of

Standard Reference Materials and a group of divisions organized by the following areas of materials research:

Analytical Chemistry—Polymers—Metallurgy — Inorganic Materials — Physical

Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides for the creation of appropriate opportunities for the use and application of technology within the Federal Government and within the civilian sector of American industry. The primary functions

of the Institute may be broadly classified as programs relating to technological meas- urements and standards and techniques for the transfer of technology. The Institute

consists of a Clearinghouse for Scientific and Technical Information,3 a Center for

Computer Sciences and Technology, and a group of technical divisions and offices organized by the following fields of technology:

Building Research—Electronic Instrumentation — Technical Analysis — Product

Evaluation—Invention and Innovation— Weights and Measures —Engineering

Standards—Vehicle Systems Research.

THE CENTER FOR RADIATION RESEARCH engages in research, measurement,

and application of radiation to the solution of Bureau mission problems and the

problems of other agencies and institutions. The Center for Radiation Research consists of the following divisions:

Reactor Radiation—Linac Radiation—Applied Radiation—Nuclear Radiation.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted ; mailing address Washington, D. C. 20234.

2 Located at Boulder, Colorado 80302.

3 Located at 5285 Port Royal Road, Springfield, Virginia 22151.
NATIONAL BUREAU OF STANDARDS REPORT

ms PROJECT NBS REPORT

2120411 December 31, 1968 9964

2120414

2120641

2120653

DEVELOPMENT, TESTING, AND EVALUATION OF VISUAL LANDING AIDS

Consolidated Progress Report to Ship Installations Division

and

Meteorological Division

N aval Air Systems Command

Department of the Navy

and to Federal Aviation Administration

For the Period

July 1 to September 30, 1968

By

Photometry Section

Metrology Division

Institute for Basic Standards

IMPORTANT NOTICE NATIONAL BUREAU OF ST/

for use within the Government,

and review. For this reason, the whole or in part, is not authori Bureau of Standards, Washingto

the Report has been specifically

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

s accounting documents intended

subjected to additional evaluation

listing of this Report, either in Office of the Director, National

y the Government agency for which

ipies for its own use. <Sis>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

Report E

9903

9904

Development, Testing, and Evaluation of Visual Landing Aids

July 1 to September 30, 1968

I. REPORTS ISSUED

Title

Development, Testing, and Evaluation of Visual Landing Aids,

Consolidated Progress Report for the period January 1 to March 31, 1968.

Development, Testing, and Evaluation of Visual Landing Aids,

Consolidated Progress Report for the period

April 1 to June 30, 1968.

9350 Supplementary Photometric Characteristics of U. S. Carrier Deck Lights

9964 2

II. VISIBILITY METERS AND THEIR APPLICATION

NBS Atmospheric Backscatter Meter (Shipboard Visibility Meter).

The atmospheric backscatter meter designed by NBS was installed just before

the start of this period and has operated throughout the quarter. The lampphotocell unit is shown as installed at the left in figure 1. In testing for an intermittant operation in the log-ratio board, the troubles suddenly disappeared and

have not reoccurred, but the cause was not located. New connectors were

installed on the lamp-voltage cable, which were intended to reduce the likelihood of breakage. The equipment operated through the quarter without serious

malfunction. The thermostat which controls the temperature in the electronics

box became erratic and would close the heater circuit at any temperature between

38°C to 42 C. The temperature ranged from 38 to 45 C, which is well beyond

the design range of 39 to 42 . This thermostat will be replaced. Near the end

of the quarter there were occasional failures to trigger the light source even when operating in the DAY mode. Later this trouble was determined to be caused

by the deterioration of the silicon-controlled rectifier (SCR) photodiode.

The response of the instrument to visibility conditions correlates very well

with atmospheric changes. The sensitivity to change in clearer visibilities is

much greater than that of the transmissometer and the sensitivity is still

adequate for visibilities down to a few hundred feet. The sensitivity to changes

in conditions for visibilities below 800 feet at night and 400 feet in daytime may

be less than desired. On one occasion in very dense fog the OUTPUT reading

became slightly negative. Backscatter meter readings have been compared with

transmissometer readings only for intermittent instances. A detailed analysis

will be needed to determine stability and effects of rain, different types of fogs,

etc.

Construction was started on spare plug-in boards for the field unit now

under test at Areata. One of each different circuit board has been completed

and tested. These are now available should any problems occur.

During the testing of the replacement log-ratio circuit board, an intermittent fault existed similar to the problem encountered with the unit at Areata.

The trouble was found to be a bad solder joint at one of the pins used to hold

components on the board. This suggests the cause of the problem at Areata. The

decision has been made to make printed circuit boards for Model II, which will

not only eliminate the component holding pins, but will reduce the total number

of solder joints.

3

Figure

1.

Fog

detectors

and

visibility

meters

installation

and

test

range.

9964 4

The present circuit design seems to be satisfactory, making design

of printed boards a relatively simple procedure. The lay-out has been

completed for all the boards, and boards have been made for the averaging,

peak-detector, and log-ratio circuits. The log-ratio circuit was designed to

incorporate the temperature-controlled transistor pair of the Fairchild

integrated circuit gA726C. This circuit has been completed and tested. A 10°C

increase in ambient temperature from room temperature caused about a 0. 3

$

of full scale change in the output for all ratios over the full 1000 to 1 range.

Without the temperature controlled integrated circuit at least a 3$ change

would occur. If the equipment is located in an environment tolerable by the

operators (50 to 100°F), temperature control of the electronics box will not

be required.

All major components for Model II have been ordered except for cabinets

or housings. These should be ordered during October to ensure delivery by

the end of the year. The 4-inch diameter, 1 -meter focal length lens must be

ordered from the optical shop. The remaining circuit boards should be completed

and tested this month.

Field Tests of Several Fog Detectors and Visibility Meters.

Operation of several types of fog detectors and visibility meters has continued.

Several of these installations are shown in figures 1 to 5. There were many

periods of fog of various densities suitable for evaluating the response of these

instruments. The field testing will continue into the next quarter. Discussion of

the performance of these instruments follows.

Videograph Fog Detector.

The Videograph B fog detector has continued to operate satisfactorily

during this quarter. This unit as installed is shown in the foreground of figure 3. The output reading is being recorded continuously and can be used as a

visibility meter indicator as well as a fog detector. These records shown good

response to changes in atmospheric conditions over the ranges of visibility which

have occurred. The response is very sensitive to changes in clearer conditions

and the unit does not completely saturate in very dense fog. Variations in

ambient temperature seem to have some effect on the sensitivity of this instrument. The performance appears very favorable, and a more complete analysis

of the data for correlation with atmospheric parameters will be made.
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1
5

Figure

2.

Early

fog

detector

installations.

NBS

Report

9964

6

7

Figure 4. AGA Visibility meter installation.

NBS Report 9964

8

Figure 5. Fog detector installation. NBS Report

Videograph B

Fog Detector

Transmissometer

Projector

AGA Fog

Detector

9964 9

AGA Visibility Meter.

The AGA visibility meter was kept in operation throughout this period.

This unit as installed inside the instrument shelter is shown in figure 4. The

loan of the equipment was extended but the equipment will be returned early

next quarter. After repairs to the lamp, the performance was much improved,

but the instrument never recovered the original sensitivity. The response was

affected by daylight, but the amount of change has not been determined. The

sensitivity to change in conditions is very great for clearer conditions, but the

unit appears to saturate for visibilities much below one mile. A more complete

analysis of the response will be required to determine the usefulness of this

equipment.

AGA Fog Detector.

The AGA fog detector has continued to operate well. This unit as installed on the transmissometer stand is shown in figure 5. On a maintenance check,

the separation of the lamp from the base was noted and the lamp was replaced.

There was no appreciable change in the transmission value at which the alarm

circuit would close either before or after the lamp replacement.

Hoffman VMS-508A Fog Detectors.

Because of the shortage of signal lines from the field test site to the

laboratory, the Hoffman VMS- 508A fog detectors have not been put back into

operation. With the removal of some of the other fog detector installations, these

two units will be reinstalled for further operation.

Edison Fog Detector.

The sensitivity of the Edison fog detector had deteriorated until useful data

was not being obtained. After replacement of the lamp, the response was improved,

but the sensitivity did not fully return to that obtained earlier. The installation

was dismantled so that the signal lines and stand could be used for other installations. Further tests of this unit are planned when a new detecting element is

obtained.

Effect of Height Above Ground on Transmission.

The installation for preliminary investigation of the effect of height on atmospheric transmission was completed at the beginning of this quarter. Three

transmissometers using the same 250-foot baseline are installed with one at

5 feet, one at 10 feet, and one at 15 feet above the ground. These units are

9964 10

located at the site previously designated as T. L2 transmissometer. The

installations of the projectors and receivers are shown in figures 1 and 6. The

indicators and recorders are located in the Field Laboratory. In advection fogs,

usually the top transmissometer indicates the lowest transmittance. In radiation or ground fog, which is less common at Areata, the bottom transmissometer usually

indicates the lowest transmittance. The center transmissometer seems to agree

more nearly with the top unit than with the bottom unit. This may indicate that the

ground effect on fog density is most noticeable in the first five feet, but extends

above 15 feet. Freauently the fog density changes rapidly, and the normal recorder

chart drive speed of 3 inches per hour is too slow to adequately correlate the three

records with the time variations. On several occasions the chart drive speed was

changed to 12 inches per hour, which permits the variations with time to be followed

satisfactorily. These transmissometers operating as the test installation will be

continued.

Transmis someters.

A memorandum on the operational life and malfunctions of the “ phototubes”

and “triggertubes” used in the photopulse unit of the transmissometers was

prepared to furnish the FAA with technical information on the reliability of

these components. Both tubes have very long operational life when tubes which

are unsatisfactory at the initial installation are eliminated. The malfunctions

in these components are rarely catastrophic failures requiring immediate

replacement, but usually are very gradual decreases in sensitivity, or instabilities of only a few percent.

A problem with crosstalk from the NBS transmissometers affecting the

indication of the FAA runway visual rarge (RVR) equipment was encountered.

This trouble occurred when the output signals of the transmissometer indicators

were fed into a tape recorder. Apparently there was some leakage of this signal

onto the signal lines to the RVR computer, although the fault or leakage path was

never identified. The RVR computer seemed to be most sensitive to this crosstalk

during the background check. The RVR computer at Areata is connected directly

to the transmissometer input signal line, where the pulses have an amplitude of

only 16 to 20 volts, and the leakage-signal pulses may have been on this order

of amplitude. If the input signal for the RVR computer were taken from the

output of the transmissometer indicator, the input could be biased to eliminate

leakage from other transmissometer signals and noise from other sources.

Fog Variability Studies.

The report of the “Summary of Low Visibility Conditions at the Areata

Airport” has been revised to include the occurrences of runway visual range (RVR)
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Figure 6. Transmissometer receiver installation to determine effect of height on transmission

tests. NBS Report 9964

9964 12

below 600 feet and the minimum RVR for each of these occurrences. Data for

low RVR in 1967 has been added. Also the low visibility and ceiling observations

for 1967 as reported by Federal Aviation Administration (FAA)-Flight Service

Station (FSS) have been added.

During this quarter, the elapsed time meters have recorded 861 hours of

instrument flight rules (IFR) conditions and 116 hours of operating runway lights

at 100 percent intensity. The metering of the time when transmittance over a 500-foot baseline is below 0. 5 has been discontinued.

9964 13

m. AIRFIELD LIGHTING AND MARKING

Flush Approach Light Manufactured by Strong Electric Corporation.

A prototjnpe flush approach light manufactured by the Strong Electric Corporation,

Toledo, Ohio, was submitted for static load tests and for before-and-after

photometric tests. The unit was lamped with two experimental 20-ampere,

500-watt, single-ended halogen-C3

rcle lamps. For the load tests strain gages

were affixed to the under side of the light head before the load was applied. The

load was applied in 10, 000 pound increments. At 40, 000 pounds cracking noises

were heard but, because of the cushioning material placed between the light and

the testing machine to distribute the load, it was not possible to determine the

souice of the noises. Testing was stopped at 80, 000 pounds, and the load was

removed. Some permanent deformation was recorded. Both exit windows were

found to be broken after the test. The light was given a photometric test before

the load test but not afterwards. The results appear in NBS Test Report 212. 11-35/68.

Flush Masher Manufactured by the Amglo Corporation.

A prototype flush flasher approach light has been received from the National

Aviation Facilities Experimental Center, Atlantic City, New Jersey, for photometric

tests. The unit is lamped with a linear Xenon flashtube delivering 450 wattseconds per flash at half-second intervals. The unit is the smaller of two made

under an FAA development contract.

Type C — 1 Lights with a Philips (Netherlands) Lamp.

Two type C-l edge lights, and four lamps manufactured by N. V. Philips

Gloeilampenfabrieken, Eindhoven, Netherlands, were received for photometric tests. Three of the lamps were broken on arrival. Tests will be made (after the receipt

of replacement lamps) to obtain a light intensity comparison between the same

fixture with the Philips and with U. S. -made lamps.

Centerline Lighting for SATS.

The four prototype centerline lights, described in NBS B'ogress Ifeport 9694,

were delivered to NATC at Lakehurst, New Jersey in July. These lights are to be

installed in a SATS system at Lakehurst for a service evaluation.

9964 14

Q6. 6A/PAR56/3 Lamps with Clear Covers.

NBS Test Report 212. 11-37/68 gives the results of photometric tests made of

twelve Q6. 6A/PAR56/3 runway-and approach-light lamps taken from a factoryproduction run. The formerly-used light-stippled cover has been replaced by a clear cover for this type lamp.

It is suggested in the report that MS24488(USAF) be modified as follows:

Minimum beam dimensions through the optical axis: 80, 000 candelas, change

from 6°H x 5°V to 5°H x 4°V. 20, 000 candelas, change from 10°H x 8°V to 11°H x

7°V. Minimum peak intensity, change from 150, 000 to 170, 000. Cover glass,

change from “stippled” to “clear”. Rated average laboratory life (hours) (burned

base down), change from 300 to 1000.

The 3040K average color temperature indicates a 1000-hour lamp. The lamps

were put on life test and a supplementary report will be issued.

Photometric Tests of 500-Watt, 20-Ampere PAR-56 Halogen Cycle Approachand Runway-Light Lamps with Clear Covers.

NBS Test Report 212. 11-45/67 contains the results of photometric measurements

made during this period of a group of eight clear cover lamps. The test was made

to determine if a lamp with a clear cover is a satisfactory replacement for the

presently-used type Q20A/PAR56/3 halogen-cycle approach- and runway-light

lamp.

Portable Inset-Light Photometer.

A conference was held with FAA personnel to discuss the feasibility of constructing a photometer to make periodic checks on the intensity of the runway inset

lights. It was decided that NBS will construct a wheel-mounted manually pushed

photometer which will be of a relatively simple and inexpensive design and intended

only for making spot checks on the system. A more complex and expensive design

will be necessary if each light is to be checked, as the time required to check each

individual light would be prohibitive using a hand-pushed device.

Gages for Checking Type L-850 Light Bases for Conformance to Specification.

The two gages (“go” and “not-go”) for checking type L-850 light bases for

dimensional conformance to specification were not acceptable as regards the spacing
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9964 15

of the boit-hole positions. The holes were rebored on a precision indexing head.

Field Tests of Cable- Fault Locator Developed by NBS.

Additional tests with the cable-fault locator were made during the dry

season when ground resistance was higher than normal. Many of these tests were

made in areas where other cables and pipes were located. Often faults were not

located or the wrong conductor would be followed. Some laboratory investigation

of the signal and response of the receiver were made. The waveform of the output

signal from the generator is affected by the load of the circuit and by the inductance

of the circuit, particularly from the isolating transformers. Some additional tests are needed to clarify performance in certain cases. These tests and a revision

of the test report should be completed next quarter.

Field Tests of Type L-842 Inset Runway Lights with JForced Drainage Modification.

These lights continue to be operated three hours daily. The forced drainage

modification appears to be of little value, because the effectiveness in removing

water from the unit depends on the lights being energized for a considerable time

after precipitation has ceased. Except to replace lamps as they fail, no further

work on this task is contemplated.

Obstruction Lights for Transmission Line Towers.

At the reauest of the FAA a scale model of a five hundred foot transmission line

tower has been assembled. It wall be used in a determination of the optimum flash

rate, flash sequence and physical location of the lights on the tower. This system

has been observed by officials from the FAA and a final observation will be made

in the near future. The proposed system tentative to a final observation wall be

using three clear lights located in approximately the center of the tower at five

hundred, three hundred and twenty-five and one hundred and fifty-foot levels. The

flash sequence will be the center light first, top light second and the bottom light third,

with a flash rate of sixty flashes per minute. The time interval between the second

and third flash will be approximately three or four times the time interval between

the first and second flash.
V

-
9964 16

IV. CARRIER LIGHTING AND MARKING

Measurement of Flight Deck Illumination and Luminance.

Instruments were received for the task of measuring flight deck illumination

and luminance on several aircraft carriers. The photometer will be calibrated

and an exploratory series of measurements will then be made, probably at NATC,

Patuxent River, Maryland.

Deck Guide Lights.

Two deck guide lights manufactured by the L. C. Doane Company, Essex,

Connecticut, were received for test. Both units are lamped with 6. 6-ampere,

200-watt, single-ended (prefocused) halogen-cycle lamps. One light is intended

for carrier deck centerline use while the other is for edge or athwart deck use. Photometric measurements were made of both units and the results appear in

NBS Test Report 212. 11-29/68.

Catupult Bridle Inspection Light.

A hand held spotlight with a low intensity narrow beam has been constructed

and delivered to NATC at Lakehurst, New Jersey. This light is equipped with a series of baffles intended to restrict the beam angle to prevent any direct light

from being seen by the pilot. This unit was left at Lakehurst for evaluation to

determine the requirements in future units as to the beam angle and intensity.

Weight Display Unit.

. The weight display unit described in NBS Progress Report 9694 was delivered

to NATC at Lakehurst, New Jersey in July.

Summary of Photometric Tests of U. S. Carrier Deck Lights.

NBS Report 9350 Supplementary was issued giving the photometric characteristics of U. S. carrier deck lights. The report includes a table of selected

characteristics, fifteen intensity distribution curves and six photographs or drawings of the lights included in the report.

Criteria for the Inspection of Fresnel Lenses.

Work on this task was postponed pending the arrival of a second cell from the

Naval Air Engineering Center (SI), Philadelphia.

9964 17

V. MISCELLANEOUS TECHNICAL AND CONSULTATIVE SERVICES

Review of Specifications and Publications.

A service bulletin, a technical manual, and several survey reports of Naval

Airfield lighting installations and equipment and visual landing aids (VLA) were

reviewed. Comments were forwarded for consideration on revisions and further

work. The publications reviewed were as follows:

1. Visual Landing Aids General Service Bulletin No. 27.

2. Technical Manual NAVAIR 51-50AAA-2 Visual Landing Aids Design

Standards —Landbased Installations.

3.

4.

5.

6 .

NAEC-ENG-7474-1

NA EC -ENG-7474-2

NAEC-ENG-7474-3

NAEC-ENG-7474-4

OLS Whitehouse Visual Landing Aids Configuration.

NAS Lemoore Visual Landing Aids Configuration.

NAS Cecil Field Visual Landing Aids Configuration.

NAS Jacksonville Visual Landing Aids Configuration.

Frequently these publications do not specify the current lamps and transformers

and the Survey reports indicate that out-dated equipment is being used. To assist

in both maintenance and design, lists of lamps and transformers are being prepared.

These lists will include type number, specification, standard drawing number,

electrical ratings, Federal stock number, fixture types and specifications, and,

when available, the superseded type, stock number, specification, and standard

drawing number. These lists will be completed next quarter.

Other documents reviewed were:

Ringo - An Alignment System for Helicopters.

Draft - Report: - Evaluation of Several Multitransmissometer Systems.

FAA Draft Specification: - Centerline Retroreflective Marker.

FAA Draft Specification: - Power and Control Assembly for Two-Box VASI.

9964 18

VI. MISCELLANEOUS

Operation Foggy Cloud.

Project Foggy Cloud is a field evaluation of methods of modifying warm fog

and stratus clouds, which has been operating at the Areata Airport since March.

This project is planned and directed by the Earth and Planetary Division of the

Naval Weapons Center in collaboration with several other government agencies.

This operation will continue to the end of the fog season. The NBS Field

Laboratory was authorized to cooperate with this project when assistance was

necessary. The NBS efforts on this project up to the end of this period are summarized as follows:

A. Project location planning.

1. Provided data and information on fog and low stratus conditions

at Areata Airport.

2. Provided information on space and facilities available at Airport.

3. Reviewed airport operation policies and past test operations.

4. Discussed available instrumentation and services.

B. Establishment of project operations.

1. Assisted in arranging for office space, storage facilities, aircraft servicing

and loading areas, and testing sites.

2. Helped plan sites and, in some cases, assisted with installation of rawin and

radar equipment, instrumentation vans, visual observation ranges, ground

seeding sites, instrument locations, and patterns for aerial seeding and

airborne instrument flights.

3. Aided in unloading equipment and supplies, advised on local sources or

contacts for services and supplies, operated forklifts and special equipment

of NBS and Humboldt County when required.

4. Provided signal and recorders (temporarily) from two transmissometers.

5. Participated in early briefings of operating plans to insure safety, to avoid

conflicts with other agencies, and to correlate observations and measurements

to evaluate results.
'
9964 19

C. Early Test Operations.

1. Provided escort vehicles (until suitable vehicles and communications were

obtained) for necessary operations on or near runways and taxiways.

2. Provided radio communications to FAA for coordinating tests with air

traffic and to relay information between test pilots and ground test

personnel.

3. Assisted in igniting and burning pyrotechnics, ‘‘salty dogs, ” and “salty frogs. ”

4. At times made and reported visual observations of conditions and results,

transported others to areas on or near taxiways and runways for observations

and measurements.

D. Continued operations.

1. Coordinated safety operations for ground seeding tests (most of this was

on our own time outside of working hours).

2. Provided transmissometer signals and special transmission data as requested.

3. Reported incidental observations which appeared pertinent to tests.

4. Moved helium tanks with forklift as required to replenish supply for rawin.

5. Permitted limited use of shop equipment, tools, meters and components

and parts.

6. Provided electrical power to some of the instrument sites.

7. Arranged for special facilities at times.

8. Provided consultation on meteorological information, prospects for fog

(short and long range), miscellaneous information.

9. Briefed special visitors on conditions and operations at Areata.

A brief summary of the Foggy Cloud operation through this season as prepared by

their personnel will be included in the next Progress Report.
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