4/18/75 AC 70/7460-1D If the top of the structure has a cover or roof, the top orange band should be continued to cover the entire top of the structure. If the object under study is a flagpole, skeletal structure or similar object erected on top of a building, the combined height of the object and building will determine whether marking is recommended;
however, only the height of the object under study determines the width of the color bands.
(b) Partial Marking. If marking is recommended on only a por Elon of a structure because of shielding by other objects or terrain, the width of the bands should be determined by the overall height of the structure. A minimum of three bands should be displayed on the upper portion of the structure.
C. Checkerboard Pattern. Checkerboard patterns of alternate rectangles of aviation surface orange and white are normally displayed on:
(1) Water, gas and grain storage tanks, excluding skeletal framework.
(2) Buildings.
Structures which appear broad from a side view, such as structures having a horizontal dimension 10.5 feet (3.2m) or greater and this horizontal dimension is equal to or greater than the
(a) Size of Rectangles. The sides of the checkerboard rectangles should measure not less than five feet (1.5m) nor more than 20 feet (6m). However, if it is impracticable because of the size or shape of a structure, the rectangle may have sides less than five feet (1.5m), provided their colore ne post of (1.5m) minimum. When possible, corner surfaces should be dimensions remain as close as practicable to the five-foot If it is technically impracticable to color the roof of a structure in a checkerboard pattern, such roof may be colored orange. If part or all of a spherical shaped structure does not permit the exact application of a checkerboard pattern, then the shape of the new rectangles may be modified to fit the shape of the spherical surface.
Chap. 3 Par. 10 Page 7
AC 70/7460-1D 4/18/75 Exceptions. does not permit coloring by a checkerboard pattern, then such obstructions should be colored by alternate bands of If the type construction of storage tanks nautical study indicates that the modified marking will provide adequate protection for air navigation. orange and white, or a limited checkerboard pattern applied to the upper one-third of the structure, provided an aero-
to its supporting standpipe. The stripes should extend from the top center of the tank Width of Stripes. (4.5m) . and the width of each stripe at the greatest girth of the tank should not be less than five feet (1.5m) nor more than 15 feet The width of the stripes should be equal maximum height of three feet (0.9m). Community Name. broken to serve this purpose. community on the side of the tank, the stripe pattern may be If it is desirable to paint the name of the This open area should have a
11. MARKERS. Markers should be used to mark obstructions when it has been Markers may also be used in addition to aviation surface orange and white colors when it has been determined that such markings should be used to determined that it is impracticable to mark such obstructions by painting.
provide protection for air commerce. They should be displayed in con- spicuous positions on or adjacent to the obstruction so as to retain tions from which an aircraft is likely to approach. They should be distinctively shaped so they are not mistaken for markers that are used to convey other information. in clear air from a distance of at least 1,000 feet (300m) in all direc- they mark is not increased. the general definition of the obstruction. They should be recognizable The shape should be such that the hazard
a. Spherical Markers. Spherical markers are normally displayed on overhead wires. Markers may be of another shape, provided the pro- jected area of such markers will not be less than that presented by a spherical marker.
overall length of the overhead line and not lower than the intervals for each 150 feet (45m), or fraction thereof, of the Display. At least one such marker should be displayed at equal highest wire, The distance between markers may be increased to not more than 600 feet (180m) when the overhead wires are Page 8 Chap. 3 Par. 10
located more than 15,000 feet (450m) from the nearest landing area. Where there is more than one overhead wire on which the spheres can be installed, the spheres may be installed alternately along each wire as long as the distance between adjacent spheres meets the spacing standard. This allows the weight and wind loading factors to be distributed.
Size and Color. The diameter of the markers should not be less than 20 inches (0.5m) and should be colored aviation orange.
b. Flag Markers. Flags may be used to mark obstructions when it has been determined that the use of coloring or spherical markers is technically impracticable.
Display. Flag markers should be displayed around, on top of the obstruction or around its highest edge. When flags are used to mark extensive obstructions or closely grouped obstructions, they should be displayed approximately 50 feet (15m) Shape. Flags should be rectangular in shape and have stiffeners to keep them from drooping in calm wind. The flag stakes should be of such strength and height that they will support the flags free of the ground, vegetation or nearby surfaces.
(3) Color Patterns. Flags should be in one of the following patterns:
(a) Solid color aviation surface orange not less than two feet
(0.6m) on a side.
(b) Two triangular sections, one of aviation surface orange and the other of aviation surface white, combined to form a rectangle not less than two feet (0, 6m) on a side.
(c) A checkerboard pattern of aviation surface orange and aviation surface white squares, each one foot (0.3m) plus or minus ten percent on a side, combined to form a rectangle not less than three feet (0.9m) on a side.
12. SPECIAL MARKINGS. 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 Used on an Airport. The FAA may also recommend appropriate marking in an area where obstructions are so grouped as to present a common hazard to air commerce.
Chap. 3 Par. 11 Page 9 (and 10)
CHAPTER 4. GENERAL APPLICATION OF LIGHTING
13. PURPOSE. The purpose of lighting a structure is to warn airmen of its presence during both daytime and nighttime conditions. To be most effective, the lighting standards herein should be adhered to exactly as described.
* 14. COLORS. Red Obstruction lights may be used during the hours of darkness, during periods of limited daytime illuminance and/or reduced meteorological visibility. High intensity white lights may be used for both daytime and nighttime conditions. Although red obstruction lighting systems and aviation surface orange and white paint are considered as meeting the minimum obstruction marking and lighting standards, the high intensity white lights are considered to be far more effective and may be recommended in lieu of red obstructin lights in some instances. Obstruction lighting may be displayed on structures in any of the following combi-
steady burning aviation red lights during nighttime operation, Aviation orange and white paint should be used for daytime marking.
b. High Intensity White Obstruction Lights. Flashing high intensity white lights during daytime with reduced intensity for twilight and nighttime operation. When this type system is used, the marking of structures with red obstruction lights and aviation orange and white paint may be omitted.
c. Dual Lighting. A combination of flashing aviation red beacons and steady burning aviation red lights for nighttime operation and flashing high intensity white lights for daytime operation. Aviation orange and white paint may be omitted.
15. APPLICATION. Whenever obstruction lights are displayed on any structure, they should be of sufficient intensity and instalied in a manner that will attract the attention of pilots approaching the obstruction from any normal angle while at any altitude up to 1,500 feet (450m) above the obstruction. Obstruction lighting may be displayed in addition to marking (paint) for daytime operation provided such lights more adequately warn airmen of the obstruction. The following factors should be considered when determining the placement of obstruction lights on a structure:
a. Heights. All heights referred to herein pertain to the obstruction's height above ground level or water, if so situated.
Determining Number of Light Levels.
(1) Red Obstruction Lighting Systems. The overall height of the structure including all appurtenances such as rods, antennas, obstruction lights, etc., is used to determine the number of Chap. 4 Par. 13 Page 11
AC 70/7460-1D 4/18/75 levels of lights. on the highest point. The top level of lights should be installed High Intensity Lighting Systems. The overall height of the mine the number of levels of lights. The top level of lights main structure, excluding all appurtenences, is used to deter- should be installed on the highest portion of the main struc- In addition, a white omnidirectional beacon should be tenance supported by the main structure. displayed on the highest portion of any antenna or other appur- C. Adjacent Structures. The 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 number of lights necessary to adequately mark an obstruction.
Shielded Lights. If any light is shielded by an adjacent object, additional lights should be mounted on that object to retain the of the obstruction. lights may be omitted if they do not contribute to the definition general definition of the obstruction, However, the additional
e. Temporary Warning Lights. When an obstruction to air navigation is be installed at the uppermost point of the structure. presented during construction of a structure, temporary lights should as the height of the structure progresses above the level at which In addition, lights are in operation. The lights should be positioned so as to permanent lights should be installed at such levels. Temporary lights should be displayed from sunset to sunrise until all of the permanent permanent obstruction lights will be required, either temporary or from aircraft at any normal angle of approach. ensure unobstructed visibility of at least one light at each level * Nonstandard Lights. Obstruction lighting other than those specified herein may be utilized provided such lighting installations offer equal or greater light intensity in all angles of azimuth and elevation equal or greater dependability of operation, possess the color characteristics prescribed in Chapter 9, and flash as required. than that specified for standard obstruction light assemblies, afford Chimneys and similar obstructions may be floodlighted by fixed search- provide an average illumination of at least 15 foo‡candles over the top one-third of the obstruction. light projectors installed at three or more equidistant points around the base of each obstruction. The searchlight projectors should Hazard Areas, An area in which a visible or invisible hazard exists or is proposed should be lighted as prescribed by FAA. This lighting would be in addition to such lighting as may be necessary on any natural or man-made obstruction located within the area.
Page 12 Chap. 4 Par. 15
h. Monitoring of Obstruction Lighting. visually observed at least once each 24 hours. In the event obstruc- Obstruction lighting should be tion lighting is not readily accessible for visual observation, a properly maintained automatic visual or audible alarm indicator should be installed and operated to provide an indication that such lights are functioning properly as required. This alarm indicator should be designed to register any malfunction of any light on the obstruction regardless of its position. The automatic monitoring alarm indicator should be located in an area generally occupied by facility personnel. In some cases, this may require relocating the monitor to a remote control station.
Cleaning. All lights, and particularly the top level, should be readily accessible to enable cleaning when necessary and to facilitate lamp/flashtube replacement. The lights should be kept clean to prevent a reduction in light output. They should be cleaned on a scheduled basis to prevent residue from accumulating on the face of the light unit and to prevent crusting due to the lamp heat.
* j• Lamp Types. Only lamps of the type supplied with FAA approved equipment or those recommended by the manufacturer as original or replacement lamps, should be used in the light fixtures. * Notification of Light Failure. Any observed or otherwise known extinguishment or improper functioning of any top steady burning light or any flashing obstruction light, regardless of its position on should be immediately reported. Such reports should be made by a natural or man-made obstruction, which will last more than 30 minutes, telephone or telegraph to the nearest flight service station or office of the FAA and should set forth the condition of the light, or lights, the circumstances which caused the failure and the probable date the operation of the light, or lights. or telegraph should be given immediately upon resumption of normal normal operation will be resumed. Further notification by telephone
1. Interference. Where obstruction lights might present a problem to the safe operation of aircraft (landing or departing), railway trains, motor vehicles and surface vessels, or if the lights might be a source of irritation to residents, consideration should be given to mitigating or eliminating the adverse effects of the lights.
Shielding of lights should be considered, steady burning lights may be made to flash, or the lower level of lights may be extinguished provided the hazard to air navigation is not increased. The FAA Regional Director or his designee is responsible for assuring that such obstruction lighting installations are fully coordinated with all parties concerned and that proper corrective measures are placed in effect. In the case of a navigable waterway, the light installation must be coordinated with the Commandant, U. S. Coast Guard, to avoid interference with marine navigation.
Chap. 4 Far. 15 Page 13
AC 70/7460-1D 4/18/75
m. Manufacturers. The names of qualified manufacturers and a description of their equipment are listed in the FAA Advisory Circular 150/5345-1, Approved Airport Lighting Equipment. See Chapter 9.
* Lighting Equipment. The standards outlined in this advisory circular ere predicated upon the use of lighting units that meet specified intensities, beam patterns, color and flash rates (if appropriate).
Therefore, only equipment having been approved by the Airports Service of the Federal Aviation Administration or nonstandards lights in accordance with paragraph 15.f. above, should be used, O • Lighting Systems) Designation. A method of designating the specific type of lighting system to be employed on a structure, and previously used to designate the number of levels and type of red obstruction lights to be used, has been expanded to cover the high intensity lighting system configurations. (See Appendix 2, Figures 1-12).
(1) Type of lighting system.
(a) A - Red obstruction lighting system
(b) B - High intensity obstruction lighting system C - High intensity obstruction lighting system with an appurtenance extending above the top of the structure.
(d) D - Dual lighting system
(2) Number of levels. The numerical designator immediately following the letter designator, identifies the number of levels of lights. * Page 14 chap. .
Par. 1.
4/18/75 AC 70/7460-1D CHAPTER 5. RED OBSTRUCTION LIGHTING STANDARDS TION LIGHTS. STANDARDS FOR LIGHTING OBSTRUCTIONS TO AIR NAVIGATION WITH RED OBSTRUC- Flashing Red Beacon. This 300 mm flashing beacon consists of two simultaneously flashing incandescent lamps of at least 620 watts with aviation red color filters. The steady burning intensity should not be less than 2,000 candelas (in red). The flashing mechanism should produce not more than 40 flashés per minute nor less than 12 flashes per minute with a period of darkness equal to approximately one-half the luminous period. If the obstruction is located within 15,000 feet (4,500m) of a landing area, the flashing frequency should be not less than 20 flashes per minute. These Specification I-6273. beacons should conform to FAA Specification CAA 446, or Military Steady Burning Red Obstruction Light. This obstruction light con- sists of one or more steady burning lamps of at least 116 watts (when used in multiple circuit), enclosed in an aviation red obstruction light globe. The intensity should be not less than 32.5 candelas. If the flashing mechanism is installed so as to make it necessary for these lights to flash, the simultaneous flashing of all lights will be permissible. These lights should conform to FAA Specification AC 150/5345-2 (L-810), or Military Specification L-7830.
C. Rated Lamp Voltage. The rated voltage of the lamp should, in each case, be not more than three percent higher than the average voltage during the hours of normal operation. across the lamp measured at the lamp socket with the lamp operating *
1. Operation of Red Lights. Red Obstruction lights should be operated y a satisfactory control device adiusted so the lights will be turned on when the north sky illuminance falls on a vertical surface to a level of not less than 35 footcandles (376.7 lux).
They should also be turned on during daytime when the flight visibility is restricted. In Alaska, however, the lights should be turned on during daytime when a prominent unlighted object cannot be seen of not less than 58 footcandles (624.3 lux), or the lights may from a distance of three statute miles. The control device should turn off the lights when the north sky illuminance rises to a level face the north sky. remain on continuously. The sensing device should, if practical,
e. Availability of Specifications.
(1) FAA Specifications CAA 446 and AC 150/5345-2 (L-810) are See Chapter 9. available free of charge from the Department of Transportation.
Chap. 5 Par. 16 Page 15
AC 70/7460-1D 4/18/75
(2) Military Specifications I-6273 and I-7830 are available free of charge from the Naval Publications and Forms Center. See Chapter 9, *
f. Poles, Towers, and Similar Skeletal Structures. The following standards apply to radio and television towers, supporting structures for overhead transmission lines and similar lacy structures. *
(1) Top Mounted Obstruction Light.
Structures Not More Than 150 Feet (45m) AGL. Two or more steady burning lights should be installed in a manner to ensure unobstructed visibility of one or more lights from an aircraft at any normal angle of approach.
(b) Structures Exceeding 150 Feet (45m) AGL. At least one 300 mm flashing beacon should be installed in a manner to ensure unobstructed visibility from an aircraft at any normal angle of approach.
(c) Special Cases.
Appurtenances Not Exceeding 20 Feet (6m). If a rod, antenna or other appurtenance of not more than 20 feet (6m) in height is incapable of supporting a beacon and it is determined that this appurtenance does not allow „unobstructed viewing of a single 300 mm flashing beacon from any normal angle of approach, there shouid be installed two such beacons properly positioned on top of the main structure to permit unobstructed viewing Appurtenances Exceeding 20 Feet (6m). If a rod, antenna or other appurtenance greater than 20 feet (6m) in height is incapable of supporting a beacon, a supporting mast with one or more beacons should be installed adjacent to the appurtenance and to a height within 20 feet (6m) of the tip of the appurtenance so as to permit unobscured viewing of at least one beacon.
(2) Mounting Intermediate Levels. The number of levels of lights may be obtained from Appendix 2, Figs: 1-3. The number of lights on each level is determined by the shape and height of the structure.
These lights should be mounted so as to ensure unobstructed viewing of at least one light from any normal angle of approach.
(a) Steady Burning Lights.
1. If the structure is not more than 450 feet (135m) in height, two or more steady burning lights should be Chap. 5 Page 16 Par. 16
4/18/75 AC 70/7460-1D installed on diagonally or diametrically opposite positions.
If the structure exceeds 450 feet (135m) in height, steady burning lights should be installed on each.
outside corner of each level.
(b) Flashing Beacons.
1. Normally, structures not more than 450 feet (135m) in height do not require intermediate levels of flashing beacons.
If the structure is more than 450 feet (135m) in height, a flashing beacon should be installed within the structure proper. If the structural members impair the viewing of the beacon, then two beacons should be mounted on the outside of diagonally or diametrically opposite positions of each level.
Chimneys, Flare Stacks and Similar Solid Structures.
(1) Top Mounted Obstruction Lights.
(a) Structures Not More Than 150 Feet (45m) AGL. At least three steady burning obstruction lights should be installed at regular intervals on the horizontal plane at or near the top, in a manner to ensure unobstructed visibility, of at least two lights from aircraft at any normal angle of approach.
(b) Structures Exceeding 150 Feet (45m) AGL. Two or more 300 m flashing beacons should be installed in a manner to ensure unobstructed visibility from an aircraft at any normal angle of approach.
(c) Chimneys. Lights may be displayed from five (1.5m) to 10 feet (3m) below the top of chimneys to avoid the obscurant effect of the deposits generally emitted by this type of structure. It is important that these lights be readily accessible to enable cleaning when necessary and to facilitate lamp replacements.
(2) Mounting Intermediate Levels,
(a) Steady Burning Lights. The number of light levels may be obtained from Appendix 2, Figs. 1-3. At least three lights should be installed on each level. These lights should be mounted so as to ensure unobstructed viewing of at least two lights on each level.
Chap. 5 Par. 16 Page 17
AC 70/7460-1D 4/18/75
(b) Flashing Beacons. The number of beacon levels may be obtained from Appendix 2, Figs, 1-3.
1. Normally, structures not more than 450 feet (135m) in beacons. height do not need intermediate levels of flashing
2. If the structure exceeds 450 feet (135m) two or more flashing beacons should be installed on each level and installed in a manner to allow unobstructed viewing of at least one beacon.
h. Prominent Buildings and Similar Extensive Obstructions. If individual objects within a group of obstructions are approximately the same overall height above ground, or water if so situated, and are located not more than 150 feet (45m) apart, the group of obstructions may be considered an extensive obstruction. Prominent buildings and follows: similar extensive obstructions should display steady burning obstruc- tion lights in a manner to indicate the extent of the obstruction as
(1) Direction. Structures Not More Than 150 Feet (45m) in Either Horizontal If the structure/extensive obstruction is not more than 150 feet (45m) in either horizontal dimension, at least one steady burning obstruction light should be displayed on the highest point of each end of the major axis of the obstruction.
If this method of lighting is impracticable because of the shape of the obstruction, then two lights may be displayed in the center of the highest point.
(2) Structures More Than 150 Feet (45m) in at Least One Horizontal one steady burning obstruction light should be displayed for each 150 feet (45m) in either or both horizontal dimensions, at least Direction. If the structure/extensive obstruction is more than 150 feet (45m), or fraction thereof, of the overall length of the major axis of the obstruction. At least one of these lights should be displayed on the highest point of each end of the obstruction. Additional lights, as required, should be displayed at approximately equal intervals not to exceed 150 feet (45m) on the highest points or edge between the end lights. If there are two or more edges of the same height on an obstruction located lighted. near a landing area, the edge nearest the landing area should be
(3) lieu of steady burning obstruction lights in the event early or Page 18 Chap. 5 Par. 16
displayed on the highest points of an extensive obstruction at intervals not exceeding 3,000 feet (900m). At least three beacons should be displayed on one side of the extensive obstruction to indicate a line of lights.
(4) If individual objects within a group of obstructions are not the same height and are spaced more than 150 feet (45m) apart, the prominent objects within the group should be lighted in accordance with the specifications for individual obstructions of a corresponding height, In addition, at least one rotating beacon should be installed at the top of a prominent center obstruction or on a special tower located near the center of the group of obstructions.
(5) Obstructions More Than 150 Feet (45m) AGL. Steady burning obstruction lights should be installed at the top as specified in paragraphs (1) or (2) above. At selected intermediate levels, steady burning lights should be displayed for each 150 feet (45m), or fraction thereof. The position of these lights on the vertical plane should be equidistant between the top lights and the ground level as the shape and type of obstruction will permit. One such light should be displayed at each outside corner on each level with the remaining lights evenly spaced between the corner lights.
i. Alternate Method of Displaying Obstruction Lights. In lieu of installing lights on the obstruction, lights may be placed on poles of slightly greater height than the obstrućtion and installed on or adjacent to the structure.
Chap. 5 Par. 16 Page 19 (and 20)