AC 70/7460-1B 1 Oct 72 *
(1) If the structure is skeletal by nature, such as a tower, two be placed on diagonally or diametrically opposite positions lights should be installed at each level. Each light should of the obstruction and mounted so as to insure unobstructed visibility of at least one light. In case of a triangular or the obstruction at each level. this level. a light should be installed on each corner of the tower at ground, lights should be installed on each outside corner of rectangular shaped tower, the lights should be mounted so as o insure unobstructed visibility of at least one light, or On towers more than 450 feet in height above
(2) If the obstruction is solid by nature, such as a smokestack, These lights should be placed at regular intervals on the there should be installed at each level at least three lights.
horizontal plane in a manner to insure unobstructed view of at least two lights on each level.
c_ Feet in Overall Height. For Towers, one or more similar flashing code beacons should be installed in Smokestacks and Similar Obstructions more than 450 At selected levels other than the cop, ity of them from aircraft at any normal angle of approach. such a position on the obstruction to insure unobstructed visibil-
(1) If the obstruction is skeletal by nature, such as a tower, the beacon should be installed within the structure proper so that the structural members will not impair its visibility. In the beacons. event this is not possible, there should be installed two such Each beacon should be mounted on the outside of at the prescribed height, diagonally opposite corners on opposite sides of the structure
(2) If the obstruction is solid by nature, such as a smokestack, two or more beacons should be installed at regular intervals on the horizontal plane in a manner to insure unobstructed visibility of at least one beacon at each level.
19. SPECIFICATIONS.
a. Towers, Poles, and Similar Obstructions. When the height of the particular obstruction above ground, or water if so situated, is:
(1) Not more than 150 feet: At the top apply 18b(1).
(2) More than 150 feet but not more than 300 feet:
(a) At the top apply 18a(1).
(b) At midpoint of the overall height apply 18b(1).
Page 26 Chap. 6 Par. 18
1 Oct 72 AC 70/7460-18
(3) More than 300 feet but not more than 450 feet:
(a) At the top apply 18a(1).
(b) At approximately two-thirds and one-third of the overall height apply 18b(1).
(4) More than 450 feet but not more than 600 feet:
(a) At the top apply 18a(1).
(b) At approximately one-half of the overall height apply 18c (1).
(c) At approximately three-fourths and one-fourth of the overall height apply 18b (1).
(5) More than 600 feet but not more than 750 feet:
(a) At the top apply 18a(1).
(b) At approximately two-fifths of the overall height apply 18c (1).
(c) At approximately four-fifths, three-fifths, and one-fifth of the overall height apply 18b(1).
More than 750 feet but not more than 900 feet:
(a) At the top apply 18a(1).
(b) At approximately two-thirds and one-third of the overall height apply 18c(1).
(c) At approximately five-sixths, one-half, and one-sixth of the overall height apply 18b(1).
(7) More than 900 feet but not more than 1050 feet:
At the top apply 18a(1).
(b) At approximately four-sevenths and two-sevenths of the overall height apply 18c(1).
At approximately six-sevenths, five-sevenths, threesevenths and one-seventh of the overall height apply 18b (1).
(8) More than 1050 feet but not more than 1200 feet:
At the top apply 18a(1).
At approximately three-fourths, one-half, and one-fourth of the overall height apply 18c(1).
At approximately seven-eighths, five-eighths, threeeighths, and one-eighth of the overall height apply 18b (1).
Chap. 6 Par. 19 Page 27
AC 70/7460-1B 1 Oct 72 * More than 1200 feet but not more than 1350 feet:
(a) At the top apply 18a(1).
At approximately two-thirds, four-ninths, and two-ninths of the overall height apply 18c(1).
At approximately eight-ninths, seven-ninths, five-ninths, one-third, and one-ninth of the overall height apply More than 1350 feet but not more than 1500 feet:
(a) At the top apply 18a(1).
(b) At approximately four-fifths, three-fifths, two-fifths, and one-fifth of the overall height apply 18c(1).
(c) At approximately nine-tenths, seven-tenths, one-half, 18b(1). three-tenths, and one-tenth of the overall height apply
(11) More than 1500 feet but not more than 1650 feet:
(a) At the top apply 18a(1).
(b) At approximately eight-elevenths, six elevenths, four- 18c(1). elevenths and two-elevenths of the overall height apply At approximately ten-elevenths, nine-elevenths, sevenelevenths, five-elevenths, three-elevenths, and one- eleventh of the overall height apply 18b(1).
(12) More than 1650 feet but not more than 1800 feet:
(a) At the top apply 18a(1).
(b) At approximately five-sixths, two-thirds, one-half, one-third, and one-sixth of the overall height apply 18c (1).
(c) At approximately eleven-twelfths, three-fourths, seventhe overall height apply 18b(1). twelfths, five-twelfths, one-fourth, and one-twelfth of More than 1800 feet but not more than 1950 feet:
(a) At the top apply 18a(1).
(b) At approximately ten-thirteenths, eight-thirteenths, six-thirteenths, four-thirteenths, and two-thirteenths, of the overall height apply 18c(1).
(c) At approximately twelve-thirteenths, eleven-thirteenths, nine-thirteenths, seven-thirteenths, five-thirteenths, three-thirteenths, and one-thirteenth of the overall height apply 18b(1).
Page 28 Chap. 6 Par. 19
1 Oct 72 AC 70/7460-1B
(14) More than 1950 feet but not more than 2100 feet:
(a) At the top apply 18a(1).
(b) At approximately six-sevenths, five-sevenths, fourof the overall height apply 18c(1). sevenths, three-sevenths, two-sevenths, and one-seventh
(c) At approximately thirteen-fourteenths, eleven-fourteenths, nine-fourteenths, one-half, five-fourteenths, three- tourteenths, and one-fourteenth of the overall height apply 1ob (1).
b. Smokestacks and Similar Obstructions. To avoid the obscurant effect of the deposits generally in evidence from this type of structure, the top lights should be installed from 5 to 10 feet below the highest point of the structure. It is important that these lights facilitate lamp replacements. be readily accessible to enable cleaning when necessary and to () Floodlighting. floodlighted by fixed searchlight projectors installed at three or more equidistant points around the base of each Smokestacks and similar obstructions may be obstruction if the searchlight projectors will provide an one-third of the obstruction. average illumination of at least 15 footcandles at the top
(2) When the height of the particular obstruction above ground or water, if so situated is:
(a) Not more than 150 feet: At a near top level apply 18b(2).
(b) More than 150 feet but not more than 300 feet:
1 At a near top level apply 18a(2).
2 At midpoint of the overall height apply 18b (2).
(c) More than 300 feet but not more than 450 feet:
1 At a near top level apply 18a(2).
At approximately two-thirds and one-third of the overall height apply 18b (2).
(d) More than 450 feet but not more than 600 feet:
1 At a near top level apply 18a(2).
2 At approximately one-half of the overall height ápply 18c (2).
3 At approximately three-fourths and one-fourth of the overall height apply 18b(2).
Chap. 6 Par. 19 Page 29
АС 70/7460-ЇВ 1 Oct 72
(e) More than 600 feet but not more than 750 feet: I At approximately two-fifths of the overall height At a near top level apply 18a(2). apply 18c(2).
3 At approximately four-fifths, three-fifths and one- fifth of the overall height apply 18b(2).
(f) More than 750 feet but not more than 900 feet: 3 At the oxtrate he fit appty 186(2-half and one-sixth 2 At approximately two-thirds and one-third of the 1 At a near top level apply 18a(2). overall height apply 18c(2).
(g) More than 900 feet but not more than 1050 feet:
1 At a near top level apply 18a(2).
3 At approximately six-sevenths, five-sevenths, three- At approximately four-sevenths and two-sevenths of 18b(2). the overall height apply 18c(2). sevenths, and one-seventh of the overall height apply
(h) More than 1050 feet but not more than 1200 feet:
3 At approximately seven-eights, five-eights, three- I At approximately three-fourths, one-half, and one- 1 At a near top level apply 18a(2). 18b(2). fourth of the overall height apply 18c(2). eights, and one-eighth of the overall height apply (і) More than 1200 feet but not more than 1350 feet:
1 At a near top level apply 18a(2).
L At approximately two-thirds, four-ninths, and two- ninths of the overall height apply 18c(2).
3 At approximately eight-ninths, seven-ninths, five- apply 18b (2). ninths, one-third, and one-ninth of the overall height
(j) More than 1350 feet but not more than 1500 feet:
1 At a near top level apply 18a(2).
fifths, and one-fifth of the overall height apply At approximately four-fifths, three-fifths, two- 18c (2).
3 At approximately nine-tenths, seven-tenths, one-half, apply 18b (2). three-tenths, and one-tenth of the overall height Page 30 Chap. 6 Par. 19
1 Oct 72 AC 70/7460-1B
(k) More than 1500 feet but not more than 1650 feet:
ž . At a near top level apply 18a(2). At approximately eight-elevenths, six-elevenths tour-elevenths, and two-elevenths of the overall height apply 18c (2).
At approximately ten-elevenths, nine-elevenths, seven-elevenths, five-elevenths, three-elevenths, and one-eleventh of the overall height apply 18b (2).
() More than 1650 feet but not more 1800 feet:
FAt approximately five-sixths, two-thirds, one-half, At a near top level apply 18a(2). one-third, and one-sixth of the overall height apply 18c (2).
At approximately eleven-twelfths, three-fourths, seven-twelfths, five-twelfths, one-fourth and onetwelfth of the overall height apply 18b(2).
(m) More than 1800 feet but not more than 1950 feet:
1 At a near top level apply 18a(2).
2 At approximately ten-thirteenths, eight-thirteenths, șix-thirteenths, four-thirteenths, and two-thirteenths of the overall height apply 18c(2).
At approximately twelve-thirteenths, eleven-thirteenths, nine-thirteenths, seven-thirteenths, fivethirteenths, three-thirteenths, and one-thirteenth of the overall height apply 18b(2).
(п) More than 1950 feet but not more than 2100 feet:
1 At a near top level apply 18a(2).
2 At approximately six-sevenths, five-sevenths, foursevenths, three-sevenths, two-sevenths, and oneseventh of the overall height apply 18c(2).
3 At approximately thirteen-fourteenths, elevenfourteenths, three-fourteenths, and one-fourteenth of * the overall height apply 18b(2). rourteenths, nine-fourteenths, one-half, five- Chap. 6 Par. 19 Page 31
AC 70/7460-1B 1 Oct 72
c. Prominent Building and Similar Extensive Obstructions. Prominent buildings and similar extensive obstructions should be lighted in accordance with the following specifications. In the event the individual objects of a group of obstructions are approximately the be considered an extensive obstruction and so lighted. same overall height above ground, or water if so situated, and are located not more than 150 feet apart, the group of obstructions may
(1) When the particular obstruction is not more than 150 feet in overall height above ground, or water if so situated:
(a) If the obstruction is not more than 150 feet in either horizontal dimension, there should be installed at the major axis of the obstruction at least one light, approximately the highest point or edge at each end of consisting of a lamp of at least 100 watts, enclosed in an aviation red obstruction light globe. These lights should be positioned so as to insure unobstructed visibility of them from aircraft at any normal angle of approach, and to indicate the general extent of the as to make this manner of lighting impracticable, there obstruction; or, if the shape of the obstruction is such may be installed two such lights at the approximate center of the highest point or edge of the obstruction. Both lights should burn simultaneously and be so positioned as to insure unobstructed visibility of at least one of the lights from aircraft at any normal angle of approach.
(b) If the obstruction is more than 150 feet in one horizontal dimension, but not more than 150 feet in the other, there should be installed at least one light, consisting of a lamp of at least 100 watts enclosed in an aviation red obstruction light globe, for each 150 feet, or axis of the obstruction. fraction thereof, of the overall length of the major At least one of these top lights should be installed on the highest point or edge of each end of the obstruction, with the additional lights as required spaced at approximately equal intervals not exceeding 150 feet, on the highest points or edge between the end lights in a manner to indicate the extent of the obstruction and to insure unobstructed visibility of the lights from aircraft at any normal angle of approach. If there are two or more edges of the same height on such an obstruction located near a be lighted. landing area, the edge nearest the landing area should Page 32 Chap. 6 Par. 19
1 Oct 72 AC 70/7460-1B
(c) If the obstruction is more than 150 feet in both horizontal dimensions, there should be installed at least one light, consisting of a lamp of at least 100 watts enclosed in an aviation red obstruction light globe, on the highest point of each corner of the at least one similar light for each 150 feet, or fraction obstruction, In addition, there should be installed hereot, when the distance between the corner lights installed at approximately equal intervals, at the 150 feet. These additional lights should be highest points along the outer edges of the obstruction, between the corner lights in a manner to indicate the general extent and definition of the obstruction and to insure unobstructed visibility of the lights from aircraft at any normal angle of approach.
(d) In the event there are one or more points within the outer edges of the obstruction, the uppermost parts of which are higher than the highest level of the lights prescribed above, at least one similar light should be displayed from the top of each such point.
(2) When the particular obstruction is more than 150 feet in overall height above ground, or water if so situated:
(a) Top lights should be installed on the obstruction in the manner set forth in the applicable provisions of Section 19c(1) above,
(b) Intermediate lights, each consisting of a lamp of at least 100 watts enclosed in an aviation red obstruction light globe, should be provided for each 150 feet, or fraction thereof, the obstruction exceeds 150 feet in overall height above ground, or water if so situated, The position of these intermediate lights on the vertical plane should be as close to the equidistant levels between the top lights and the ground level as the particular shape and type of obstruction will permit.
One such light should be installed at each outside corner of the obstruction at each level and also one such light should be installed at equal intervals on the horizontal plane on each outer surface at each level between adjacent corner lights, for each 150 feet, or fraction thereof, when the overall horizontal distance between such adjacent corner lights exceeds 150 feet.
Chap. 6 10 D=0a 73
AC 70/7460-1B 1 Oct 72 1 In lieu of installing the obstruction lights on the obstruction, a pole or poles of height slightly greater than the overall height of the obstruction may be installed on or adjacent to the obstruction and lighted in accordance with the specifications prescribed in Section 19a.
2 It is important that those towers, poles, or similar structures be installed in such a manner as to indicate the general definition and extent of the obstruction.
(c) In the event early or special warning is considered necessary to provide adequate protection for aircraft, the top lights on each obstruction as required under Section 19c(1) and 19c(2) above, should be replaced with described in Section 18a. one or more flashing 300 m electric code beacons as
(d) Where obstructions are extensive as in the case of a line of trees or hills, and the use of the fixed obstruction lights would be impracticable or inadequate, flashing or rotating hazard beacons may be used as an alternate to the fixed obstruction lights. Such beacons should be obstruction at intervals not exceedirg 3,000 feet, pro- vided at least three beacons are placed on any one side located on the highest points or edges of the extended or edge of the extensive obstruction to indicate a line of lights. The flashing or rotating beacons should be of the type described in Chapter 5 of this circular,
d. Bridges. accordance with the following specifications. However, where the bridge structure is over navigable water, approval of the lighting installation must be obtained from the Commandant of the United States Coast Guard to avoid interference with marine navigation. The superstructure of a bridge should be lighted in
(1) When the bridge Superstructure is not more than 1,50 feet in overall length: There should be installed at the approximate center of the highest point of the superstructure at least two lights, each light consisting of a lamp of at least 100 watts, enclosed in aviation red obstruction light globes, two lights should burn simultaneously and should be positioned The so as to insure unobstructed visibility of at least one of the lights from aircraft at any normal angle of approach, Page 34 Chap. 6 Par, 19
1 Oct 72 AC 70/7460-1B
(2) length: When the bridge superstructure is more than 150 feet in overall
(a) There should be installed for each 150 feet, or fraction thereof, of the overall length of the bridge superstructure one or more lights, each light consisting of a lamp i at least 100 watts, enclosed in aviation red obstructior light globes. These lights should be installed on the highest points of the superstructures at approximately equal intervals not exceeding 150 feet in a manner to indicate the general definition and extent of the obstruction, and to insure unobstructed visibility of the lights from aircraft at any normal angle of approach, The distance between these top lights may be increased to a distance not exceeding 600 feet when the particular bridge is located more than 15,000 feet from the reference point of any landing area.
(b) Where the bridge superstructure exceeds 150 feet in overall length and the use of the above described obstruction lights would be impracticable or inadequate, flashing or rotating hazard beacons should be used as an alternate to the fixed obstruction lights. Such beacons should be located on the highest points or edge of the bridge superstructure at intervals not exceeding 3,000 feet, provided at least three beacons are installed to indicate the extent of the obstruction. The flashing or rotating beacons should be of the type described in Chapter 5 of
e. Water Towers, Grain Elevators, Gas Holders, and Similar Obstructions.
should be lighted in accordance with the following specifications, Water towers, grain elevators, gas holders, and similar obstructions when the particular obstruction is:
Not more than 150 feet in overall height above ground, or water if so situated:
(a) At the top apply 18b(2).
(2) More than 150 feet but not more than 300 feet:
(a) At the top apply 18a(2).
(b) At the approximate midpoint of the overall height (as equidistant between the ground and the top of the structure as the shape of the obstruction will permit) apply 18b(2).
Chap. 6 Par. 19 Page 35
AC 70/7460-1B 1 Oct 72
(3) More than 300 feet but not more than 450 feet:
(a) At the top apply 18a(2).
(Б) At approximately two-thirds and one-third of the overall height apply 18b (2).
f. Group of Structural Hazards. Towers, poles, tanks, smokestacks, and similar obstructions which are so grouped as to present a common potential hazard to air navigation should be lighted in accordance
(1) This specification applies to a group of closely spaced towers, poles, tanks, smokestacks, or similar obstruction of approximately the same overall height above ground, or water it so situated, in which the spacing between the individual structures does not exceed 150 feet. The group may be considered an extensive obstruction and lighted in accordance with Section C.
"Prominent Buildings and Similar Extensive Obstructions."
This specification applies to a group of closely spaced towers, poles, tanks, smokestacks, and similar obstructions which may or may not be of the same overall height, in which the spacing between the individual structures is not in all cases equal to or less than 150 feet. Each prominent object within the group should be lighted in accordance with the specifications preobstructions of a corresponding overall height above ground, or water if so situated. scribed in the section for individual towers, poles and similar In addition, there 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, at least one rotating beacon producing aviation red flashes.
(b) The rotating beacon should be of the type described in Chapter 5 of this circular.
Page 36 Chap. 6 Par. 19
1 Oct 72 AC 70/7460-1B
g. Trees. A line of trees, with the individual trees located less than 150 feet apart, or a tree-covered area should be lighted as an extensive obstruction as specified in Paragraph 19c, Prominent Buildings and Similar Extensive Obstructions, with the obstruction lights mounted on poles or towers, of a height slightly greater than the height of the outstanding trees. Individual trees and widelyspaced trees should be lighted in accordance with the following specification: Poles of a height slightly greater than the height of the outstanding tree(s) should be installed adjacent to the tree(s) and lighted in accordance with Section 19a.
h. 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.
chap • • ar. is Page 37 (and 38)