1 Oct 72 AC 70/7460-1B * (4) Beachball Pattern. Water towers with a single circular standpipe support may be colored in the beachball striped pattern.
The storage tank should be colored to show alternate stripes of aviation surface orange and white. The stripes should extend from the top center of the tank to its supporting standpipe.
The width of the stripes should be equal and the width of each band at the greatest girth of the tank should be not less than five feet nor more than 15 feet. If it is desirable to paint the name of the community on the side of the tank, the stripe pattern may be broken for a sufficient distance to serve this feet. purpose. This open area should have a maximum height of three C. Exceptions.
(1) Combined Patterns. If a part of a water tower, gas holder, building, or similar obstruction consists of a skeletal-type construction, that portion of the obstruction should be colored with alternate bands of aviation surface orange and white as specified for towers, poles, smokestacks and similar obstructions. In this case, if the portion of the obstruction which is to be colored to show a checkerboard pattern of alternate rectangles of aviation surface orange and white, has any surfaces the projection of which on any vertical plane is less than 15 feet in either dimension, the alternate rectangles of aviation surface orange and white may have dimensions of less than five feet on a side, provided their dimensions remain as close as practicable to the minimum five feet specified for coloring by the checkerboard pattern,
(2) Bands on Certain Structures. If the size and shape of water towers, grain elevators, gas holders, and similar obstructions come within the dimensions set forth under the specification for coloring by bands, or if their type of construction does not permit coloring by the checkerboard pattern described in b(3) above, then such obstructions should be colored by bands as specified for towers, poles, smokestacks, and similar obstructions. Where this method of coloring is employed, the top aviation surface orange band should be continued from the vertical surface so as to cover the entire top of the obstruction.
Chap. 3 Par. 9 Page 9
AC 70/7460-1B 1 Oct 72
(3) of aviation surface orange and white covering the spherical shape may be modified to fit the particular shape of the Spherical Shaped Structures. If a part, or all, of certain shape does not permit the exact application of the checkerboard pattern of coloring, then the shape of the alternate rectangles obstructions such as water towers and gas holders of spherical structural surface, provided the dimensions of these modified checkerboard pattern. limits set forth in the specifications for coloring by the rectangles remain to the extent practicable within the dimensional
(4) Limited Pattern. If certain obstructions such as gas holders of the checkerboard pattern of coloring may be limited to the of the checkerboard pattern of coloring to the complete outer surface of the structure would be impracticable, the application and grain elevators are of such large size that the application protection for air navigation. upper one-third of the structure, provided the aeronautical study indicates that the modified marking will provide adequate
d. Special.
Marking of Vehicles. Vehicles customarily used on landing areas should be marked in accordance with the provisions of Advisory Circular 150/5210-5, Painting, Marking and lighting of Vehicles
(2) Buildings or Similar Obstructions. When the upper portion of a building or similar extensive obstruction projects above an airport imaginary surface, as described in Part 77 of the Federal Aviation Regulations, the point or edge of it highest in relation to the airport imaginary surface should be regarded as the "top of the obstruction." 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 referenced surface may not be the highest point or edge above a horizontal plane passing of the object, the upper parts of which are higher above a horizontal plane passing through the base of the object than through the base of the object. In such cases, those portions should also be obstruction marked. the upper part considered as the "top of the obstruction," Hazard Areas. The FAA may recommend appropriate marking in an area where towers, poles, and similar obstructions are so grouped as to present a common hazard to air commerce; where the hazard of a particular obstruction is increased by guy wires or other appurtenances; or, where an invisible hazard to aircraft Page 10 Chap. 3 Par. 9
1 Oct 72 AC 70/7460-1B 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. To accomplish this objective, it is necessary to display lighting on the obstruction of sufficient intensity, and 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 at obstruction. any altitude up to 1,500 feet above the uppermost point on the
11. 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 or lights, should be installed on the points or edges of the that when no airport imaginary surface is involved, such top light, obstruction highest in relation to the ground, or water if so situated. If two or more edges of an extended obstruction located near any landing and takeoff area of an airport are of the same height, an obstruction lighting is to be displayed on only one of lighted. 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 definition of the obstruction. light, or lights, being omitted if it does not contribute to the Chap. 4 Par. 10 Page 11
AC 70/7460-1B 1 Oct 72
12. QUALITIES OF LIGHTING. obstruction lights shall be aviation red in color; except that, the The signal emitted by hazard beacons and signal emitted by high intensity obstruction lights may be white.
a. Aviation Red Obstruction Lights.
Intensity.
(a) Flashing Obstruction Beacon. The integral of the timeintensity curve of each flash emitted by a flashing obatruction beacon, measured in the direction corresponding to the peak intensity and integrated over a period not exceeding 1.0 second, should be not less than 1,500 candle-seconds of aviation red light.
tentity bates Be flash at edgy of the timeobstruction beacon, measured in the direction corresponding to the peak intenaity and integrated over a period not exceeding 0,5 second, should be not less than 7,500 candle-seconds of aviation red light.
(c) Fixed Obstruction Lights. The intensity of fixed obstruction lights should be not less than 10 candelas of aviation red light.
Distribution. The vertical and horizontal light distribution of the fixed obstruction lights should meet the requirements specified in the pertinent specifications listed in this publication, The vertical light distribution of the flashing and rotating obstruction beacons should be such that the 1° and 3° above the horizontal 18 not less than the candle- seconds values specified above under "(1) Intensity," and time-intensity integral of the flashes at angles between the time-intenaity integral at angles between 3° and 15° above the horizontal is not lees 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 satiafactory output by obstruction lights, the rated voltage of the lamp should, in each case, correspond to or be within 3 percent higher than the average voltage across the lamp during the normal hours oi operation.
Page 12 Chap. 4 Par. 12
1 Oct 72 AC 70/7460-1B
b. High Intensity White Obstruction Lights.
Source. Advisory Circular 150/5345-43B, FAA/DOD Specification publication which provides the specification requirements for L-856, High Intensity Obstruction Lighting Systems, is the publication, these lights. The following 1s information from that
(2) Intensity. (Refer to paragraph 22b for transmission lines and their support structures.)
(a) Daytime - Visibility Less Than Five Miles. For daytime, when the meteorological visual range is less than five miles, the effective intensity of the lights should not horizontal plane. be less than 200,000 candelas at every point in the
(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 horizontal plane, not less than 100,000 candelas at every point in the
(c) Nighttime. For night conditions the light intensity should be reduced to 1,000 candelas.
(d) Nighttime - Dual Lighting Systems. In lieu of operating the high intensity white obstruction lights at a reduced lighting may be provided by aviation red obstruction intensity during night conditions, nighttime obstruction lighting installed and operated in accordance with the standards contained in Chapter 6 of this publication, intensity white obstruction lights should (Where dual lighting systems are shued, be installed and operated at the closest level associated with an aviation red obstruction light or hazard beacon in this publication.) accordance with the standards contained in Chapter 8 of
(3) Distribution.
(a) Vertical. The vertical beam spread everywhere around the no less than 3o and to 10 percent of its effective intensity light to 50 percent of its effective intensity shall be Chap. 4 Par. 12 Page 13
AC 70/7460-1B 1 Oct 72 Horizontal. The distribution of light should be at least horizontal plane. the minimum prescribed intensity at all points on the
(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
(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, page 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 should be continuous. north sky illuminance rises to a level of 58 footcandles, or Page 14 Chap. 4 Par, 12
1 Oct 72 AC 70/7460-1B * 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 half footcandle. to three footcandles, but before that illuminance reaches one-
(3) 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.
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 70/7460-1B I Oct 72 * Automatic Alarm System. is not readily accessible for visual observation at least once In the event the obstruction lighting may be installed and operated to replace the normally required visual inspection. Under such conditions the FAA will not failure of the lights and to provide indication of such failure, each 24 hours, an automatic alarm system, designed to detect any percent of their normal life expectancy. Xenon flash tubes are exempted from this replacement requirement. all top lights; and that all obstruction lighting mounted on the obstruction are visually inspected at least once every two weeks, intervals after being lighted the equivalent of not more than 75 with all the lamps and/or light units being replaced at regular lights, regardless of their position on the obstruction, and of all flashing and rotating beacons and/or high intensity white provided the signalling device will indicate malfunctioning of lights on an obstruction being excluded from the alarm circuit, object to the side or intermediate aviation red obstruction
(2) Lamp Replacement. Except as specified in paragraph 13c(1), a immediate replacement purposes at all times. sufficient supply of spare lamps should be maintained for
d. ment or improper functioning is not necessary. corrected as soon as possible, but notification of such extinguish- or lights, installed on a natural or man-made obstruction should be normal operation by the light, or lights. Any extinguishment or improper functioning of a steady burning side or intermediate light, by telephone or telegraph to the nearest flight service station or lights, the circumstance 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 minutes, should be immediately reported. Such reports should be made office of FAA and should set forth the condition of the light, or Notification of Light Failure. Any observed or otherwise known of any natural or man-made obstruction, which will last more than 30 beacon light, regardless of its position on a natural or man-nade steady burning obstruction light, installed at the top or near top obstruction, which will last more than 30 minutes, and any observed or otherwise known extinguishment or improper functioning of a extinguishment or improper functioning of a flashing and rotating rage 16 Спар. 4
I Oct 72 AC 70/7460-1B
e. Flashing Frequency of Aviation Red Obstruction Lights,
(1) Aviation Red Rotating Beacon. An aviation red rotating beacon more than 15 times per minute. should produce a flash not less than 12 times per minute nor 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 minute 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 landing 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 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.
(b) 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.
Par.
AC 70/7460-1B I Oct 72 taneous flashing of all lights will be permissible. Aviation Red Intermediate Lights. necessary for the intermediate lights to flash, the simul- in obstruction lighting circuits is installed so as to make it If the flashing mechanism should be 40 flashes per minute with deviation from this flash rate not greater than plus or minus five percent. level must flash simultaneously. The flash rate of each light from any direction from the obstruction and all lights on the same high intensity white obstruction lights, except those used to mark obstruction that appear as a vertical line of lights when viewed Flashing Frequency of High Intensity White Obstruction Lights. All transmission lines and their support structures, displayed on an
14. SPECIAL CONDITIONS.
a. Lighting Variables. Obstruction lighting shall be displayed on following combinations: smokestacks, chimneys, and similar obstructions in any of the
(3) (2) Chapter 8, for daytime operation. and flashing high intensity white lights, as specified in steady burning aviation red lights for nighttime operation Lights. A combination of flashing aviation red beacons and Combination Aviation Red and High Intensity White Obstruction during both daytime and nighttime operation. High Intensity White Obstruction Lights. Flashing high intensity white obstruction lights, as specified in Chapter 7, in Chapter 6, during nighttime operation. beacons and steady burning aviation red lights, as specified Aviation Red Obstruction Lights. Flashing aviation red Interference. Where any obstruction lights displayed on an should be given to mitigating or eliminating the adverse effects person or persons in the vicinity of the lights, consideration trains or motor vehicles, or may be a source of irritation to any obstruction may present a problem to the safe operation of railway Page 18 Chap. 4 Par. 13
1 Oct 72 AC 70/7460-1B 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 if doing so will not materially increase the hazard to air be found necessary to manually shield or extinguish that light, 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 ' marine navigation. Commandant, United States Coast Guard to avoid interference with
(3) 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 70/7460-1B 1 Oct 72
d. additional obstruction lights should be placed on the highest part airport imaginary surface may not be the highest above a horizontal to the airport imaginary surface. of the object as well as on the point or edge highest in relation (i.e., sloping), this point or edge highest in relation to the plane passing through the base of the object. imaginary surface concerned is an approach or transition surface tion, In certain cases, however, such as when the airport imaginary surface should be regarded as theitop of the obstruc- Building Lighting. When the upper portion of a building or surface, as described in Part 77 of the Federal Aviation Regula- similar extensive object projects above an airport imaginary tions, the point or edge highest in relation to the airport In such cases,
e. 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 lighting fixtures at each required level, in lieu of the above temporary warning lights, as each such level is exceeded in height practicable, to install and operate the permanent obstruction lights have been installed and placed in operation, and should be approach. It will be permissible, in the event it is more ed nightly from sunset to sunrise until the permanent obstruction of the lights at each level from aircraft at any normal angle of positioned so as to insure unobstructed visibility of at least one lights will be required, two similar lights should be installed at the structure exceeds each level at which permanent obstruction each such level. Thesę temporary warning lights should be display- uppermost point of the structure, In addition, as the height of an aviation red obstruction light globe, should be installed at the
f. Obstruction Lighting by Nonstandard Lights. Obstruction lighting greater light intensity in all angles of azimuth and elevation than characteristics prescribed in Chapter 5. cent lamps, provided such lighting installations offer equal or that specified for standard obstruction light assemblies, afford equal or greater dependability of operation, and possess the color specified under the recommended lamp equipment, gaseous tubes such installations may utilize incandescent lamps other than those as neon tubes, or any method other than the conventional incandes- Page 20 Chap. 4 Par. 14