1 Jan 72 AC 70/7460-1A CHAPTER 4. LIGHTING PURPOSE. The purpose of lighting an object that may be an obstruction to air navigation is to warn airmen of its presence during the hours of darkness and during periods of limited daytime light intensity and meteorological visibility. Io accomplish this objective, it is necessary to display lighting on the obstruction of sufficient intensity, anc in such a manner, that it will attract the attention of the pilot of any airplane that is approaching the obstruction from any angle while obstruction. at any altitude up to 1,500 feet above the uppermost point on the I1. LOCATION OF LIGHTING. The following factors should be considered when determining the placement of obstruction lights on a structure as specified in Chapters 6, 7 and 8:
Adjacent Structures. The mean elevation of the tops of the buildings in closely built up areas may be used as the equivalent of the ground level when determining the proper amount of obstruction lighting necessary to adequately mark an obstruction.
Top Lighting. The top light, or lights, displayed on an obstruction should be installed so as to mark the points or edges of the obstruction highest in relation to an airport imaginary surface, as described in Part 77 of the Federal Aviation Regulations, except that when no airport imaginary surface is involved, such top light, or lights, should be installed on the points or edges of the obstruction highest in relation to the ground, or water it so situated. It two or more edges of an extended obstruction located near any landing and takeoff area of an airport are of the same height, and obstruction lighting is to be displayed on only one of the edges, the edge nearest the landing and takeoff area should be
c. Shielded Lights, If a light, or lights, which is installed on an obstruction is shielded in any direction by an adjacent object, additional lights should be mounted on that object in such a way as to retain the general definition of the obstruction, the shielded light, or lights, being omitted if it does not contribute to the definition of the obstruction.
Chap. 4 Par. 10 Page 11
AC 70/7460-1A 1 Jan 72 * 12. QUALITIES OF LIGHTING, signal emitted by high intensity obstruction lights may be white, obstruction lights shall be aviation red in color; except that, the The signal emitted by hazard beacons and
a. Aviation Red Obstruction Lights.
(1) Intensity.
(a) Flashing Hazard Beacon, The integral of the time-intensity curve of each flash emitted by a flashing hazard beacon, measured in the direction corresponding to the peak intensity and integrated over a period not exceeding 1.0 aviation red light. second, should be not less than 1,500 candle-seconds of
(b) Rotating Hazard Beacon. The integral of the time-intensity curve of each flash emitted by a rotating hazard beacon, measured in the direction corresponding to the peak intensity and integrated over a period not exceeding of aviation red light. 0.5 second, should be not less than 7,500 candle-seconds Fixed Obstruction Lights. The intensity of fixed aviation red light. obstruction lights should be not less than 10 candelas of
(2) Distribution. of the fixed obstruction lights should meet the requirements The vertical and horizontal light distribution specified in the pertinent specifications listed in this publication. The vertical light distribution of the flashing and rotating hazard beacons should be such that the timeintensity integral of the flashes at angles between 1° and 30 above the horizontal is not less than the candle-seconds values " and the time-intensity not less than the product of these candle-seconds values multiplied by 9 over the square of the numerical value in degrees of the angle above the horizontal.
(3) Rated Lamp Voltage. To provide satisfactory output by obstruction lights, the rated voltage of the lamp should, in each case, correspond to or be within 3 percent higher than of operation. the average voltage across the lamp during the normal hours * Page 12 Chap. 4 Par. 12
1 Jan 72 AC 70/7460-1A * b. High Intensity White Obstruction Lights.
(1) Source. Advisory Circular No. 150/5345-43A, FAA/DOD Specification L-856, High Intensity Obstruction Lighting System is the publication which provides the specification requirements for these lights. The following is information from that
(2) Intensity. (Refer to paragraph 22b for transmission lines and their support structures.)
plane.
(b) Daytime - Visibility Five Miles or More. For daytime, when the meteorological visual range is five miles or more, the effective intensity of the lights should be not less than 100,000 candelas at every point in the horizontal plane.
Nighttime. For night conditions the light intensity should be reduced to 1,000 candelas.
Nighttime - Dual Lighting Systems, In lieu of operating the high intensity white obstruction lights at a reduced intensity during night conditions, nighttime obstruction lighting may be provided by aviation red obstruction lighting installed and operated in accordance with the standards contained in Chapter 6 of this publication.
(Where dual lighting systems are utilized, the high intensity white obstruction lights should be installed and operated at the closest level associated with an aviation red obstruction light or hazard beacon in accordance with the standards contained in Chapter 8 of this publication.)
(3) Distribution,
(a) Vertical. The vertical beam spread everywhere around the light to 50 percent of its effective intensity shall be no less than 3° and to 10 percent of its effective intensity no less than 6°. * Chap..
Par. Page 13
AC 70/7460-1A 1 Jan 72 * (b) Horizontal. The distribution of light should be at least the minimum prescribed intensity at all points on the horizontal plane.
(c) Adjustment. Means should be provided to allow adjustment of the beams) after installation so that the center(s) of the beam(s) can be positioned to any point from 0° to at least go above the horizontal.
(4) Measurement. The effective intensity of the light output in candelas should be determined from the Blondel-Rey equation and calculated as shown in the Illuminating Engineering Society, Guide for Calculating the Effective Intensity of Flashing Signal Lights, published in Illuminating Engineering Volume LIX p. 747 (November 1964) (available from the Illuminating Engineering Society, 345 East 47th Street, New York, New York 10017).
13. OPERATION OF OBSTRUCTION LIGHTING.
a. Hours of Operation. Aviation red obstruction lights and hazard beacons should be operated at all times when the center of the sun's disc is 6° or more below the horizon and during daytime when flight visibility is restricted. In Alaska, this would include the period during which a prominent unlighted object cannot be seen from a distance of three statute miles or the sun is 6° or more below the horizon whichever is more restrictive.
b . Control of Obstruction Lighting.
(1) Aviation Red Obstruction Lighting. The operation of aviation red obstruction lighting installed on obstructions should be controlled by a satisfactory control device. The control device used should be adjusted so that the lights will be operated at all times when the north sky illuminance falls to a level of 35 footcandles and will be turned off when the north sky illuminance rises to a level of 58 footcandles, or should be continuous.
Chap. 4 Page 14 Par. 12
1 Jan '2 AC 70/7460-1A * High Intensity White Obstruction Lighting. The operation of high intensity white obstruction lighting installed on obstructions should be controlled by a satisfactory control device.
The control device used should be adjusted so that the lights will be turned on at their highest daytime intensity when the north sky light illuminance rises to one-half footcandle, but before that illuminance level reacnes three footcandles.
high intensity white obstruction lighting is displayed on an obstruction during nighttime periods, the lighting should be controlled by a satisfactory control device. The control device used should be adjusted so that the lights will be turned on at the lower (night) intensity when the north sky illuminance falls to three footcandles, but before that illuminance reaches onehalf footcandle.
Dual Obstruction Lighting Systems. When high intensity white obstruction lighting is displayed on an obstruction during the daylight hours and only aviation red obstruction lighting is displayed on that obstruction during the nighttime hours, the two lighting systems should be controlled by one or more satisfactory control devices. The control devices used should be adjusted so that the high intensity white obstruction lights will be turned on and the red lights turned off when the north sky illuminance rises to one-half footcandle but before that illuminance reaches three footcandles, and will be turned off and the red lights turned on when the north sky illuminance falls to three footcandles but before that illuminance level reaches one-half footcandle.
(4) it ed to perfectiong Light Control Device. The operation of obstruction lighting displayed on obstructions should be controlled by one or more automatic time control, manual switching or light sensitive control devices. If a light-sensitive control device is used, it should be adjusted as in this subsection and installed so that the illuminance sensing device faces the north sky.
c. Inspection of Obstruction Lighting. Obstruction lighting should be visually observed at least once each 24 hours, or checked by observing an automatic and properly maintained indicator designed to register any failure of such lights to insure that all such lights are functioning properly as required.
Chap. 4 Par. 13 Page 15
AC 70/7460-1A 1 Jan 72 * Automatic Alarm System. In the event the obstruction lighting is not readily accessible for visual observation at least once each 24 hours, an automatic alarm system, designed to detect any failure of the lights and to provide indication of such failure, may be installed and operated to replace the normally required visual inspection. Under such conditions the FAA will not object to the side or intermediate aviation red obstruction lights on an obstruction being excluded from the alarm circuit, provided the signalling device will indicate malfunctioning of all flashing and rotating beacons and/or high intensity white lights, regardless of their position on the obstruction, and of all top lights; and that all obstruction lighting mounted on the obstruction are visually inspected at least once every two weeks, with all the lamps and/or light units being replaced at regular intervals after being lighted the equivalent of not more than 75 percent of their normal life expectancy. Xenon flash tubes are exempted from this replacement requirement.
Lamp Replacement. Except as specified in paragraph 13c(1), a sufficient supply of spare lamps should be maintained for immediate replacement purposes at all times. * Notification of Light Failure. Any observed or otherwise known extinguishment or improper functioning of a flashing and rotating beacon light, regardless of its position on a natural or man-made obstruction, which will last more than 30 minutes, and any observed or otherwise known extinguishment or improper functioning of a steady burning obstruction light, installed at the top or near top of any natura. or man-made obstruction, which will last more than Ju minutes, should be immediately reported. Such reports should be made by telephone or telegraph to the nearest flight service station or office of FAA and should set forth the condition of the light, or lights, the circunstance which caused the failure and the probable date that normal operation will be resumed. Further notification by telephone or telegraph should be given immediately upon resumption of normal operation by the light, or lights. Any extinguishment or improper functioning of a steady burning side or intermediate light, or lights, installed on a natural or man-made obstruction should be corrected as soon as possible, but notification of such extinguishment or improper functioning is not necessary.
Chap. 4 Page 16 Par. 13
I Jan 72 AC 70/7460-1A
e. Flashing Frequency of Aviation Red Lights.
() Aviation Red Rotating Beacon. An aviation red rotating beacon should produce a flash not less than 12 times per minute nor more than 15 times per minute.
(2) Aviation Red Flashing Beacon, An aviation red flashing Beacon should be equipped with a flashing mechanism producing not more than 40 flashes per minute nor less than 12 flashes per min.te with a period of darkness equal to approximately one-half the luminous period, except that the frequency of flashes of an obstruction beacon mounted on an obstruction located within 15,000 feet of the reference point of a lancing area should be not less than 20 per minute. A flashing beacon may flash an International Morse Code Signal for purposes of identification, provided the code characteristic does not consist of more than two letters, the proper aviation color characteristic is retained, and the luminous output of the beacon is not affected in such a manner as to reduce the beacon's effectiveness in performing the service for which it was originally installed, The duration of the illumination and eclipse periods is important to insure a maximum light intensity. Therefore, an effort should be made to have code assignments adjusted, insofar as possible, to the following timing:
Duration of dot - 0.5 second Duration of dash - 1.5 seconds Duration of eclipse - 0.5 second between dots and dashes of a particular letter Duration of eclipse - 1,5 seconds between letter and repetition of single letter characteristics Duration of eclipse - 2,0 seconds between characteristics which contain two letters (а) Each proposal to have a flashing beacon flash an identifying code should be coordinated with the FAA official designated by the regional director having jurisdiction over the functions of the FAA in the area in which the particular beacon is located, (Б) Approval must be obtained from the Federal Communications Commission for the modification of any obstruction lighting system which comes within the jurisdiction of that agency.
Chap. 4 Par. 13 Page 17
AC 70/7460-1A 1 Jan 72
(3) Aviation Red Intermediate Lights. If the flashing mechanism in obstruction lighting circuits is installed so as to make it necessary for the intermediate lights to flash, the simultaneous flashing of all lights will be permissible.
f. Flashing Frequency of High Intensity White Obstruction Lights, All high intensity white obstruction lights, except those used to mark transmission lines and their support structures, displayed on an obstruction that appear as a vertical line of lights when viewed from any direction from the obstruction should flash in synchronism;
however, all such white obstruction lights displayed on an obstruction may be flashed synchronously. The flash rate of each light should be 40 flashes per minute with deviation from this flash rate not greater than plus or minus five percent.
14. SPECIAL CONDITIONS.
a. Lighting Variables. Obstruction lighting shall be displayed on smokestacks, chimneys, and similar obstructions in any of the following combinations:
(1) Aviation Red Obstruction Lights. Flashing aviation red beacons and steady burning aviation red lights, as specified in Chapter 6, during nighttime operation.
(2) High Intensity White Obstruction Lights. Flashing high intensity white obstruction lights, as specified in Chapter 7, during both daytime and nighttime operation.
Combination Aviation Red and High Intensity White Obstruction Lights. A combination of flashing aviation red beacons and steady burning aviation red lights for nighttime operation and flashing high intensity white lights as specified in Chapter 8 for daytime operation. * Interference. Where any obstruction lights displayed on an obstruction may present a problem to the safe operation of railway trains or motor vehicles, or may be a source of irritation to any person or persons in the vicinity of the lights, consideration should be given to mitigating or eliminating the adverse effects of the lights.
Chap. 4 Page 18 Par. 13
1 Jan 72 AC 70/7460-1A Railroads. Where aviation red obstruction lighting is installed on obstructions which are located along or near railroad rightsof-way and thereby constitutes a potential hazard to the safe operation of railway trains, extreme care should be taken to prevent any possibility of these obstruction lights being mistaken by locomotive engineers for railway signal lights.
Shielding of the obstruction lights from the view of the locomotive engineers, if practicable, should be considered; the steady burning lights on the obstruction may be made to flash;
or the lights at the lower levels of the obstruction may be extinguished if their extinguishment does not materially the obstruction. increase the hazard to air navigation caused by the presence of
(2) Other Situations, Where high intensity white lighting is installed on obstructions which are located near highways, waterways or in populated areas, the angle above the horizontal be found necessary to manually shield or extinguish that light, if doing so will not materially increase the hazard to air of the light beam of the lowest light may be increased or it may navigation, to avoid a potential hazard to surface transportation or agitation to residents of private dwellings. If the waterway is navigable, the light installation must be coordinated with the Commandant, United States Coast Guard to avoid interference with marine navigation.
Responsibility. The FAA official designated by the regional director is responsible for assuring that such obstruction lighting installations are fully coordinated with all parties concerned and that proper corrective measures are determined and placed in effect.
Day Lighting. The display of flashing or steady burning lights during daylight hours on an obstruction to provide protection in addition to that provided by the applicable marking standards described in Chapter 3, may be prescribed in some instances to more adequately warn airmen of the presence of such an obstruction.
Chap. 4 Par. 14 Page 19
AC 70/7460-1A 1 Jan 72 Building Lighting. similar extensive object projects above an airport imaginary When the upper portion of a building or surface, as described in Part 77 of the Federal Aviation Regulations, the point or edge highest in relation to the airport imaginary surface should be regarded as the "top of the obstruc- tion.i In certain cases, however, such as when the airport imaginary surface concerned is an approach or transition surface
(i.e., sloping), this point or edge highest in relation to the airport imaginary surface may not be the highest above a horizontal plane passing through the base of the object. In such cases, additional obstruction lights should be placed on the highest part of the object as well as on the point or edge highest in relation to the airport imaginary surface, Temporary Warning Lights. When an obstruction to air navigation is presented during construction of a structure at least two lights, each light consisting of a lamp of at least 100 watts enclosed in an aviation red obstruction light globe, should be installed at the the structure exceeds each level at which permanent obstruction uppermost point of the structure. In addition, as the height of lights will be required, two similar lights should be installed at each such level. These temporary warning lights should be displayed nightly from sunset to sunrise until the permanent obstruction lights have been installed and placed in operation, and should be positioned so as to insure unobstructed visibility of at least one of the lights at each level from aircraft at any normal angle of approach. It will be permissible, in the event it is more practicable, to install and operate the permanent obstruction lighting fixtures at each required level, in lieu of the above during construction. temporary warning lights, as each such level is exceeded in height Obstruction Lighting by Nonstandard Lights. Obstruction lighting installations may utilize incandescent lamps other than those specified under the recommended lamp equipment, gaseous tubes such as neon tubes, or any method other than the conventional incandescent lamps, provided such lighting installations offer equal or greater light intensity in all angles of azimuth and elevation than that specified for standard obstruction light assemblies, afford equal or greater dependability of operation, and possess the color characteristics prescribed in Chapter 5.
Page 20 Chap. 4 Par. 14
1 Jan 72 AC 70/7460-1A CHAPTER 5. OBSTRUCTION MARKING AND LIGHTING EQUIPMENT
15. PAINT. Paint and aviation colors referred to in the standards set tions: forth in this publication should conform with the following specifica-
(1) Orange No. 12197 (Aviation Surface Orange).
(2) White No. 17875 (Aviation White).
b. Aviation Surface Paint.
* (1) Federal Specification TT-P-59 Paint, Ready-Mixed, Internation- al Orange.
(2) Federal Specification TT-P-102 Paint, 0il, Titanium-Lead-Zinc and 01l, Exterior, Ready-Mixed, white and light tints.
16. LIGHTS AND ASSOCIATED EQUIPMENT. The lighting equipment referred to in the standards set forth in this publication should conform with the drawings. applicable provisions of the following specifications and their related
a. Aviation Red Obstruction Lighting Systems.
(1) Color. Military Specification MIL-C-25050 Colors; Aeronautical Lights and Lighting Equipment.
(2) Rotating Beacons.
(a) FAA Specification 291. Beacons, 36-inch, Rotating Double-Ended Type.
(b) Military Specification MIL-L-7158. Lamp Assembly, 24- inch, Rigid Drum-type Rotating Beacon,
(3) Flashing Code Beacons, FAA Specification 446. Code Beacons, 300 mm.
(4) Double and Single Obstruction Lights.
(a) Military Specification MIL-L-7830. Light, Navigational Boundary and Obstruction Markers.
(b) FAA Specification L-810. Specification for Obstruction Light.
Chap. 5 Par. 15 Page 21
AC 70/7460-1A 1 Jan 72
(5) Lights). MIL-C-7989. Covers; Light-transmitting (for Aeronautical Covers for Aeronautical Lights. Military Specification
b. High Intensity White Obstruction Lighting System.
Specification 1-856, High Intensity Obstruction Lighting Specification. The high intensity white lighting system should conform with the applicable provisions of FAA/DOD referred to in the standards set forth in this publication
(2) Availability of Specifications. FAA/DOD Specification L-856 Transportation, Distribution Unit, IAD-484.3, Washington, D. C. may be obtained free of charge from the Department of Circular No. 150/5345-43A. Copies of this advisory circular is contained in the Federal Aviation Administration Advisory
(3) Manufacturers. The names of qualified manufacturers and a Distribution Unit, TAD-484.3, Washington, D. C. 20590. obtained free of charge from the Department of Transportation' * 5345-1C, Approved Airport Lighting Equipment. Copies may be Federal Aviation Administration Advisory Circular No. 150/ Page 22 Chap. 5 Par. 16