IRImplementing rule
CS ADR-DSN.Q.852Marking and lighting of overhead wires, cables, supporting towers, etc.
(a)Marking: The wires, cables, etc. to be marked should be equipped with markers; the supporting tower should be coloured.
(b)Marking by colours: The supporting towers of overhead wires, cables, etc. that require marking should be marked in accordance with CS ADR-DSN.Q.845(b), except that the marking of the supporting towers may be omitted when they are lighted by high-intensity obstacle lights by day.
(c)Marking by markers:
(1)Markers displayed on or adjacent to objects should be located in conspicuous positions so as to retain the general definition of the object and should be recognisable in clear weather from a distance of at least 1 000 m for an object to be viewed from the air and 300 m for an object to be viewed from the ground in all directions in which an aircraft is likely to approach the object. The shape of markers should be distinctive to the extent necessary to ensure that they are not mistaken for markers employed to convey other information, and they should be such that the hazard presented by the object they mark is not increased.
(2)A marker displayed on an overhead wire, cable, etc., should be spherical and have a diameter of not less than 60 cm.
(3)The spacing between two consecutive markers, or between a marker and a supporting tower, should be appropriate to the diameter of the marker. The spacing should normally not exceed:
(i)30 m where the marker diameter is 60 cm, increasing progressively with increase of the marker diameter to:
(ii)35 m where the marker diameter is 80 cm; and
(iii)further progressive increases to a maximum of 40 m where the marker diameter is of at least 130 cm. Where multiple wires, cables, etc., are involved, a marker should be located not lower than the level of the highest wire at the point marked.
(4)A marker should be of one colour. When installed, white and red, or white and orange, markers should be displayed alternately. The colour selected should contrast with the background against which it should be seen.
(5)When it has been determined that an overhead wire, cable, etc., needs to be marked but it is not practicable to install markers on the wire, cable, etc., then high-intensity obstacle lights, Type B, should be provided on their supporting towers.
(d)Lighting:
(1)High-intensity obstacle lights, Type B, should be used to indicate the presence of the tower supporting overhead wires, cables, etc. where:
(i)a safety assessment indicates such light to be essential for the recognition of the presence of wires, cables, etc.; or
(ii)it has not been found practicable to install marker on the wires, cables, etc.
(2)Where high-intensity obstacle lights, Type B, are used, they should be located at three levels:
(i)at the top of the tower;
(ii)at the lowest level of the catenary of the wires or cables; and
(iii)at approximately midway between these two levels.
(3)High-intensity obstacle lights, Type B, indicating the presence of a tower supporting overhead wires, cables, etc., should flash sequentially; first the middle light, second the top light, and last the bottom light. The intervals between flashes of the lights should approximate the following ratios:
| Flash interval between | Ratio of cycle time |
|---|---|
| Middle and top light | 1/13 |
| Top and bottom light | 2/13 |
| Bottom and middle light | 10/13 |
(4)The installation setting angles for high-intensity obstacle lights, Types B, should be in accordance with Table Q-5.
| (1) | (2) | (3) | (4) | (5) | (6) | (7) |
|---|---|---|---|---|---|---|
| Light type | Colour | Signal type/ (Flash Rate) | Peak intensity (cd) at given Background Luminance (b) | Light Distribution Table | ||
| Day (Above 500 cd/m2) | Twilight (50-500 cd/m2) | Night (Below 50 cd/m2) | ||||
| Low-intensity Type A (fixed obstacle) | Red | Fixed | N/A | N/A | 10 | Table Q-2 |
| Low-intensity Type B (fixed obstacle) | Red | Fixed | N/A | N/A | 32 | Table Q-2 |
| Low-intensity Type C (mobile obstacle) | Yellow/ Blue (a) | Flashing (60-90 fpm) | N/A | 40 | 40 | Table Q-2 |
| Low-intensity Type D (follow-me vehicle) | Yellow | Flashing (60-90 fpm) | N/A | 200 | 200 | Table Q-2 |
| Low-intensity, Type E | Red | Flashing (c) | N/A | N/A | 32 | Table Q-2 (Type B) |
| Medium-intensity Type A | White | Flashing (20-60 fpm) | 20 000 | 20 000 | 2 000 | Table Q-3 |
| Medium-intensity Type B | Red | Flashing (20-60 fpm) | N/A | N/A | 2 000 | Table Q-3 |
| Medium-intensity Type C | Red | Fixed | N/A | N/A | 2 000 | Table Q-3 |
| High-intensity Type A | White | Flashing (40-60 fpm) | 200 000 | 20 000 | 2 000 | Table Q-3 |
| High-intensity Type B | White | Flashing (40-60 fpm) | 100 000 | 20 000 | 2 000 | Table Q-3 |
| (a) ADR.OPS.B.080(a)(2), AMC1 ADR.OPS.B.080(a) and AMC2 ADR.OPS.B.080(a) (b) For flashing lights, effective intensity as determined in accordance with ICAO Doc 9157, Aerodrome Design Manual, Part 4, Visual Aids. (c) For wind turbine application, to flash at the same rate as the lighting on the nacelle. | ||||||
Table Q-1. Characteristics of obstacle lights
| Minimum intensity (a) | Maximum intensity (a) | Vertical beam spread (f) | ||
|---|---|---|---|---|
| Minimum beam spread | Intensity | |||
| Type A | 10 cd (b) | N/A | 10° | 5 cd |
| Type B | 32 cd (b) | N/A | 10° | 16 cd |
| Type C | 40 cd (b) | 400 cd | 12(d) | 20 cd |
| Type D | 200 cd (c) | 400 cd | N/A(e) | N/A |
| Note: This table does not include recommended horizontal beam spreads. CS ADR-DSN.Q.846(c) requires 360° coverage around an obstacle. Therefore, the number of lights needed to meet this requirement will depend on the horizontal beam spreads of each light as well as the shape of the obstacle. Thus, with narrower beam spreads, more lights will be required. (a) 360° horizontal. For flashing lights, the intensity is read into effective intensity, as determined in accordance with ICAO, Aerodrome Design Manual, Part 4, Visual Aids. (b) Between 2 and 10° vertical. Elevation vertical angles are referenced to the horizontal when the light is levelled. (c) Between 2 and 20° vertical. Elevation vertical angles are referenced to the horizontal when the light is levelled. (d) Peak intensity should be located at approximately 2.5° vertical. (e) Peak intensity should be located at approximately 17° vertical. (f) Beam spread is defined as the angle between the horizontal plan and the directions for which the intensity exceeds that mentioned in the ‘intensity’ column. | ||||
Table Q-2. Light distribution for low-intensity obstacle lights
| Benchmark intensity | Minimum requirements | Recommendations | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Vertical elevation angle (b) | Vertical beam spread (c) | Vertical elevation angle (b) | Vertical beam spread (c) | ||||||||
| 0° | -1° | 0° | -1° | -10° | |||||||
| Minimum average intensity (a) | Minimum intensity (a) | Minimum intensity (a) | Minimum beam spread | Intensity (a) | Maximum intensity (a) | Maximum intensity (a) | Maximum intensity (a) | Maximum beam spread | Intensity (a) | ||
| 200 000 | 200 000 | 150 000 | 75 000 | 3° | 75 000 | 250 000 | 112 500 | 7 500 | 7° | 75 000 | |
| 100 000 | 100 000 | 75 000 | 37 500 | 3° | 37 500 | 125 000 | 56 250 | 3 750 | 7° | 37 500 | |
| 20 000 | 20 000 | 15 000 | 7 500 | 3° | 7 500 | 25 000 | 11 250 | 750 | N/A | N/A | |
| 2 000 | 2 000 | 1 500 | 750 | 3° | 750 | 2 500 | 1 125 | 75 | N/A | N/A | |
| Note: This table does not include recommended horizontal beam spreads. CS ADR-DSN.Q.846(c) requires 360° coverage around an obstacle. Therefore, the number of lights needed to meet this requirement will depend on the horizontal beam spreads of each light as well as the shape of the obstacle. Thus, with narrower beam spreads, more lights will be required. (a) 360° horizontal. All intensities are expressed in Candela. For flashing lights, the intensity is read into effective intensity, as determined in accordance with ICAO Doc 9157, Aerodrome Design Manual, Part 4, Visual Aids. (b) Elevation vertical angles are referenced to the horizontal when the light unit is levelled. (c) Beam spread is defined as the angle between the horizontal plan and the directions for which the intensity exceeds that mentioned in the ‘intensity’ column. Note: an extended beam spread may be necessary under specific configuration and justified by a safety assessment. | |||||||||||
Table Q-3. Light distribution for medium- and high-intensity obstacle lights according to benchmark intensities of Table Q-1
| Longest dimension | Band width | |
|---|---|---|
| Greater than | Not exceeding | |
| 1.5 m | 210 m | 1/7 of longest dimension |
| 210 m | 270 m | 1/9 “ “ “ |
| 270 m | 330 m | 1/11 “ “ “ |
| 330 m | 390 m | 1/13 “ “ “ |
| 390 m | 450 m | 1/15 “ “ “ |
| 450 m | 510 m | 1/17 “ “ “ |
| 510 m | 570 m | 1/19 “ “ “ |
| 570 m | 630 m | 1/21 “ “ “ |
Table Q-4. Marking band widths
| Height of light unit above terrain (AGL) | Angle of the peak of the beam above the horizontal | |
|---|---|---|
| Greater than | Not exceeding | |
| 151 m | 0° | |
| 122 m | 151 m | 1° |
| 92 m | 122 m | 2° |
| 92 m | 3° | |
Table Q-5. Installation setting angles for high-intensity obstacle lights
[Issue: ADR-DSN/3]
[Issue: ADR-DSN/4]
[Issue: ADR-DSN/6]
[Issue: ADR-DSN/7]
IR · CS ADR-DSN.Q.852 — Regulation (EU) No 139/2014 · ED Decision 2025/004/R · Aerodromes Easy Access Rules · EAR revision 13 Mar 2026