4/18/75 AC 70/7460-1D
g. Chimneys, Flare Stacks and Similar Solid Structures. The number of levels of lights • commended depends on the height of the structure and may be obtained from Appendix 2, Figs. 4-6. The amount of light units recommended for each level is dependent on the outside diameter of the structure but should in no case be less than three.
The light units should be installed in a manner to ensure unobstructed viewing of the system from aircraft at any normal angle of approach.
Normally, the top level of light units are installed on the highest point of a structure. However, in the case of shimneys, the top level of lights may be installed from five (1.5m) to 10 feet (3m) below the top. This is to avoid the obscurant effects of the deposits generally emitted by this type structure.
h. Radio and Television Towers and Similar Skeletal Structures.
Mounting of Lights. The number of levels recommended depends on the height of the structure, excluding antennas and similar appurtenances, and may be obtained from Appendix 2, Figs. 7-9.
At least three lights should be installed on each level and mounted so that the effective. intensity over the full beam is not impaired by the structural members. They should be mounted in a manner to ensure unobstructed viewing from aircraft at any normal angle of approach.
(2) Ice Shields. Where climatic conditions dictate, metal grates or similar protective ice shields should be installed directly over each light unit to prevent falling ice accumulation from damaging the light units.
Top Level of Lights. One level of lights should be installed at the highest point of the structure. If the highest point is a rod or antenna incapable of supporting a lighting system then the top level of lights should be installed at the highest portion of the main skeletal structure. If the rod or antenna is more than 20 feet (6m) above the main structure, a white capacitor discharge omnidirectional light should be mounted on the highest point.
If the appurtenance (such as a whip antenna) is incapable of supporting the omnidirectional light, 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.
(4) Intermediate Levels of Lights. The intermediate levels of lights should be installed at approximately the same heights shown in Appendix 2, Figs. 7-9.
i. Hyperbolic Cooling Towers.
Mounting of Obstruction Lights. The light units should be installed in a manner to ensure unobstructed visibility of at least two lights from aircraft at any normal angle of approach.
Chap. 6 Par. 17 Page 25
AC 70/7460-1D 4/18/75 More than one light unit should be visible to provide the required intensity about the structure and to indicate to pilots the magnitude of the structure.
(2) Top Level of Obstruction Lights. The number of light units recommended depends on the diameter of the structure at the top. See paragraph 17.e.(2).
(3) Structures Exceeding 600 feet (180m) AGL. Structures greater than 600 feet (180m) AGL should have one additional level of light units installed approximately mid-point on the structure and in line with the top level of lights.
j. Supporting Structures of Overhead Transmission (Catenary) Lines.
(1) Purpose. The purpose of marking the supporting structures of lighting system is to warn pilots of the presence of the support overhead transmission lines with a unique, sequentially flashing catenary line. structures themselves and to alert pilots that they support a
(2) Mounting of Obstruction Lights. A system of three levels of sequentially flashing light units should be installed on each supporting structure (or adjacent terrain) of an overhead transmission line. One level should be installed at the top of the structure; one at the height of the lowest point in the catenary; and one level at approximately midway between the of 50 feet (15m) from the other two levels. If the installation The middle level should normally be a minimum of the top level of lights presents a potential danger to maintenance personnel, or is necessary for lightning protection, such lights may be mounted from five (1.5m) to 10 feet (3n) The flash sequence should be middle level, top level and bottom level with all lights on the same level flashing simultaneously. The time delay between flashes of the levels is designed to present a unique system display similar to a flash of lightning.
(b) Flash Rate. Each series of flashes is repeated 60 times every minute.
(c) Horizontal Coverage. Two or more light units should be installed at each light level and directed on a horizontal plane such as to provide 180 degrees of coverage centered on the transmission line. Where a catenary crossing is situated near a bend in a river, canyon, etc., the direction Page 26 Chap. 6 Par. 17
of the horizontal beam pattern should be directed to provide the most effective light coverage to warn pilots approaching from either direction of the presence of the transmission lines.
Variation. The vertical and horizontal arrangements of the lights may be subject to the structural limits of the towers and/or adjacent terrain and a tolerance of 20 percent from uniform spacing of the bottom and middle light is allowed, If the base of the supporting structure(s) is higher than the lowest point in the catenary, such as a canyon crossing, one or more lights should be installed on the adjacent terrain at the level of the lowest point in Special Cases. Where lighting systems are installed on supporting structures located near vehicular bridges, waterways, ensure that the lights do not cause a hazard to motorists' In airport approach areas, etc., caution should be exercised to vessel operators or pilots on an approach to an airport.
these cases, shielding or an adjustment to the vertical or horizontal light direction may be necessary. This adjustment should not derogate the intended purpose of the lighting system.
Area Surrounding Support Structures. The area in the immediate vicinity of the base of the supporting structures should be cleared of all structures and objects of natural growth that could interfere with the line-of-sight between a pilot and the
(5) Omission of Standard Marking. When the high intensity obstruction lighting system is used to identify a catenary line crossing, the following marking and lighting may be omitted:
(a) Spherical markers on the lines.
(b) The marking of the supporting structures for the surface area having the same exposure covered by this lighting system.
(c) The installation of red obstruction lights on the supporting structures serving the same exposure covered by the high intensity obstruction lighting system.
Total Elimination of Marking and Red Obstruction Lights.
Transmission line supporting structures having a catenary extending in one direction only and obstruction lighted as out-.
lined under paragraph 17.j. (2) may omit the standard marking and red obstruction lighting provided:
Chap. 6 Par. 17 Page 27
AC 70/7460-1D 4/18/75
(a) At least three light units are installed on the top level and situated so as to provide 360 degrees coverage about the structure. Four lights should be used if any light is installed more than 20 feet (6m) from another light on the top level. In addition, four light units may be required to effectively cover the approach to the structure dependent upon the beam pattern of the light unit and possible directions of approach, In certain situations, it may be desirable to have three lights on the top level of one supporting structure and four on the companion structure to provide adequate obstruction lighting coverage.
Structures exceeding 500 feet (150m) above ground, or water if so situated, have at least three light units installed at the middle level to provide 360 degrees coverage.
(c) All lights at each level flash simultaneously.
Three or More Supporting Structures. Where a transmission line crossing requires three or more supporting structures, the inner structures should be equipped with three or four light units per level to provide 360 degrees coverage. The number will depend upon the bean pattern of the particular manufacturer's light and the area desired to be covered as determined by the possible directions of approach. Four lights should be used if any light is installed more than 20 feet (6m) from another light on any level. Structures equipped with a lighting system providing 360 degrees of coverage about the structure may delete the standard marking and red obstruction lighting system.
Prominent Buildings, Observation Towers and Similar Extensive Obstructions. Prominent obstructions should have lights installed at the highest portion or edge of the obstruction, on the same horizontal plane and provide 360 degrees of coverage about the obstruc- They should be installed in a manner to indicate the extent of the obstruction and to ensure unobstructed visibility of at least two light units from aircraft at any normal angle of approach.
(1) If the obstruction is not more than 200 feet (60m) in either horizontal dimension, there should be installed at the highest portion of the structure three or more light units in a manner to ensure that at least one light is visible from aircraft at any normal angle of approach. They may be mounted on a single pedestal at or near the center of the obstruction. If the light units are placed more than 20 feet (6m) from a central point, a minimum of four light units should be used.
Page 28 Par. 17 Chap. 6
4/18/75 AC 70/7460-1D * (2) If the obstruction is more than 200 feet (60m) in one horizontal dimension, but not more than 200 feet (60m) in the other, two light units should be placed on each of the shorter sides.
These light units may either be installed adjacent to each other at the mid-point of the edge of the obstruction or at or near each corner and directed horizontally such as to give 180 degrees of coverage to each end of the obstruction. One or more light units should be installed along the overall length of the major axis. These lights should be installed at approximately equal intervals not to exceed a distance of 100 feet (30m) from the corners or from each other.
(3) If the obstruction is more than 200 feet (60m) in both horizontal dimensions, there should be installed one light unit for each 100 feet (30m) or fraction thereof of the overall perimeter of the obstruction.
Chap. 6 Par. 17 Page 29 (and 30)
CHAPTER 7. DUAL LIGHTING SYSTEMS
18. DUAL LIGHTING SYSTEMS. Red (nighttime) and high intensity white (daytime) obstruction lighting systems may be utilized under certain conditions when it might not be feasible to operate the high intensity white lighting systems at night. The use of the high intensity white lights for daytime obstruction lighting precludes the painting recommendations.
The systems should be installed and operated as specified in Chapters 4, 5 and 6. The light units should be installed as though each system was the only system being used. However, the levels of lights recommended for the high intensity lighting systems may be adjusted, if necessary, to coincide with the nearest platform used for the red obstruction lights.
The lights should be installed as specified in Appendix 2, Figs. 10-12.
Chap. 7 Par. 18 Page 31 (and 32)
4/18/75 AC 70/7460-1D CHAPTER 8. MARKING AND LIGHTING OF MOORED BALLOONS AND KITES
19. PURPOSE. To describe marking and lighting standards for moored balloons from any normal angle of approach. of these objects and to warn pilots of their presence when converging and kites for the purpose of indicating to airmen the general definition
20. APPLICATION. This chapter pertains to all moored balloons and kites which require marking and lighting under Part 101 of the Federal Aviation Regulations.
21. mooring lines to warn airmen of their presence during daylight hours. MARKING. Pennant, streamers or similar type markers should be used on earth and should be visible for at least one mile. se waite for af last one were the wife of the
b. Shape. Markers should be rectangular in shape and not less than two feet on a side. Stiffeners should be used in the borders to prevent drooping in calm wind, wrapping around the cable, and to expose a
c. Color Patterns. One of the following color patterns should be used:
(1) Solid color aviation orange.
(2) Two triangular sections, one of aviation orange and the other of white, combined to form a rectangle.
22. LIGHTING. that lights meeting the L-856 specifications be used.) balloons or kites and their mooring lines to warn airmen of their pres- ence during the hours between sunset and sunrise or, they may remain on continuously. Xenon type lights are acceptable, (It 19 not intended High intensity white flashing lights should be used on moored Display• tion, tail section and on the tether cable approximately 15 feet (4.5m) below the craft so as to define the extremes of size and Flashing lights should be displayed on the top, nose secshape. Additional lights should be equally spaced along the cable's overall length for each 350 feet (105m) or fraction thereof.
b. Light Distribution. The intensity of each light should be approxi- mately 1,000, and preferably 1,500, effective candelas at every point in the horizontal plane (and a minimum of two degrees in the vertical plane) with a flash rate of 40 pulses per minute.
Chap. 8 Par. 19 Page 33
AC 70/7460-1D 4/18/75
23. LIGHT CONTROL DEVICE. The operation of each light may be controlled by a photocell controller which automatically turns the light on when the north illumination on a vertical surface drops to 60 footcandles but before reaching 30 footcandles. The reverse order should apply in transitioning from nighttime to daytime operation.
24. OTHER FEDERAL OR LOCAL COVERNMENT REGULATIONS. Rules and regulations as prescribed by the FAA and other Federal and local government agencies pertaining to the use of balloons, kites and associated equipment in the navigable airspace are not affected and shall apply.
Page 34 Chap. 8 Par. 23
CHAPTER 9. OBSTRUCTION MARKING AND LIGHTING EQUIPMENT
25. PURPOSE. This chapter lists all of the documents relating to the obstruction painting and lighting of objects and advises where they may be obtained.
26. PAINT. Paint and aviation colors referred to in the standards set forth in this publication should conform to Federal Standards FED-STD-595, Colors, as follows:
a. Colors.
(1) Orange Number 12197 (Aviation Surface Orange).
(2) White Number 17875 (Aviation White).
b. Availability of Specifications. FED-STD-595 and other Federal specifications describing the technical characteristics of various paints and their application techniques may be obtained Specification Activity Building 197, Room 301 Naval Weapons Plant First and N Streets, S. E.
washington, D. C. 20407
27. LIGHTS AND ASSOCIATED EQUIPMENT. The lighting equipment referred to in drawings. applicable provisions of the following specifications and their related the standards set forth in this publication should conform with the
a. Aviation Red Obstruction Lighting System.
(1) Color. Military Specification MIL-C-25050 Colors; Aeronautical Lights and Lighting Equipment.
(2) Flashing Beacons. FAA Specification CAA 446, Code Beacons, 300 mm.
(3) Double and Single Obstruction Lights.
(a) Military Specification MIL-L-7830, Light, Navigational Boundary and Obstruction Markers.
(b) FAA Advisory Circular Number 150/5345-2, Specifications for L-810 Obstruction Light.
Chap. 9 Par. 27 . Page 35
AC: 70/7460- 1D 4/18/75 Covers for Aeronautical Lights. Military Specification MIL-C-7989 Covers; Light-Transmitting (for Aeronautical Lights).
High Intensity White Obstruction Lighting Systems. Circular Number 150/5345-43, FAA/DOD Specification L-856, High Intensity Obstruction Lighting Systems. FAA Advisory Approved Manufacturera. FAA Advisory Circular Number 150/5345-1, Approved Airport Lighting Equipment, lists the approved airport lighting equipment and manufacturers qualified to supply their pro- duct in accordance with the indicated specification requirements.
d. Installation and Maintenance. FAA Advisory Circular Number 150/5340-21, Airport Miscellaneous Lighting Visual Aids, provides tion of the red beacon and steady burning obstruction lighting. guidance for the installation, maintenance and testing and inspec-
(1) Military Specifications:
Commanding Officer Naval Publications and Forms Center 5801 Tabor Avenue Attention: NPFC-105 Philadelphia, Pennsyivania 19120
(2) FAA Specifications: • *% Chief, Configuration Control Branch, AAF-110 Department of Transportation Federal Aviation Administration 800 Independence Avenue, S.W.
Washington, D.C. 20591 * (3) FAA Advisory Circulars:
Department of Transportation Publications Section, TAD-443.1 400 7th Street, S.W. 5. 20390 Washington, D.C. * Page 36 Chap. S Par. 27
5L/81/7 AC 70/7460-1D
RECOMMENDED LAMP EQUIPMENT Multiple Circuits Average 10 Rated Lab. Approx. Specifications "sduy Ting Base Life (Hours) Lumens FAA MIL Double & Single 125 120V A-21 Md. Pf. 6,000 1,220 L-810 I-7830 Obstruction 116 120V A-21 Md. Scr 6,000 1,260 L-810 L-7830 Flashing 700 120V PS-40 Mg. Pf. 6,000 11,200 446 I-6273 Beacon 620 120V PS-40 Mg. Pf. 3,000 11,200 446 I-6273 High 480V L-856 Intensity 240V white 120V Obstruction Lights Series Circuit Obstruction IA-21 Md. Pf. 2,000 1,020 1-810 L-7830 Lights Chap. 9 Par. 27 Page 37
4/18/75 AC 70/7460-1D Appendix 1
SINGLE OBSTRUCTION
LIGHT FITTING (Fresnel Globe) 300 mm BEACON DOUBLE OBSTRUCTION (Fresnel Lens)
LIGHT FITTING (Fresnel Globe)
TYPES OF OBSTRUCTION LIGHTS Fig. I.