Frequently Asked Questions

faq aircraft warning light image

Do you have some questions about aviation obstruction systems? So, here is the place you can get your answers.

If you couldn’t find your answer or have a different kind of question about aircraft warning systems, feel free to contact with us via e-mail or phone.

 

What does aviation obstruction light mean?

Aviation obstruction lights are used to reduce the hazards to all kind of aircraft such as airplanes, helicopters, drones etc. by indicating the presence of obstructions.

These obstructions could be fixed or mobile objects.  should be marked in order to avoid collision risks near airports or heliports.

Also, it might be necessary to mark high structures which are in airplane or helicopter air traffic zone. These obstacles could be tall buildings, chimneys, power transmission line pylons, wind turbines, bridges etc.

Aviation obstruction lights also called as aircraft warning lights are lighting devices that are installed to high structures and are used as collision avoidance measures. Aviation obstruction lights make structures more visible to passing aircrafts such as airplanes, helicopters, drones and are usually used at night, although they can be used during the day as well. The intensity of aviation obstruction lights could be low, medium and high depending on the candelas.

Why should we use an Aviation obstruction light?

We are in the 21st century, the aviation sector has developed a lot and some international organizations, such as ICAO and FAA, have introduced some rules and standarts to ensure flight safety. For example ICAO Annex 14, FAA and TSHK standarts.

You do not have to use an aviation obstruction light (AWL) for every building, tower crane, chimney or other high structures. If any structure which is higher than 45m, it needs to be visual marking with aviation obstruction lights at the night time. Also If it exceeds 150 m, it has to be marked day and night time.

Is there a national or international regulation / rule on this subject?

Yes, ICAO Annex-14 chapter 6 and FAA Advisory Circular regulations lead us about how to mark/and or light tall structures and aviation obstruction lights.

What are the types of aircraft warning lights?

Please check below table;

Characteristics of obstacle lights

Characteristics of obstacle lights

Note.— This table does not include recommended horizontal beam spreads. 6.3.22 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.

What type of light should be used in which situations?

Low intensity lights should be used for structure with H ≤ 45 m during night time, if those are considered inadequate, than medium – high intensity lights should be used.

Medium intensity lights type A,B or C should be used to lit extensive object (group of buildings or tree) or structure with 45 m < H ≤ 150 m.

Note: Medium intensity lights, type A and C should be used alone, whereas medium intensity lights, Type B should be used either alone or in combination with LIOL-B.

High intensity type A, should be used to indicate the presence of an object if its H > 150 m and an aeronautical study indicates such lights to be essential for the recognition of the object by day.

* also please check our application page for more details.

What is the difference between type A and type B?

FOR LOW INTENSITY OBSTRUCTION LIGHT (LIOL)

  • Type A (Intensity>10 cd)steady red lightRED-STEADY BURNING LIGHT
  • Type B (Intensity>32 cd)steady red lightRED-STEADY BURNING LIGHT
  • Type B (Intensity>32 cd)flashing red lightRED-FLASHING LIGHT

 

LIOL-A or B should be used for structure with H ≤ 45 m during night time

Note: If those are considered inadequate or a special warning is required, then medium – high intensity lights should be used.

LIOL-B should be used either alone or in combination with MIOL-B. (This rule is also valid for object with height included between 45 m and 150 m above ground level

 

MEDIUM INTENSITY OBSTRUCTION LIGHT (MIOL)

  • Type Aflashing white light(used both day and night time) WHITE-FLASHING LIGHT
  • Type Bflashing red light(used only during night time) RED-FLASHING LIGHT
  • Type Csteady red light(used only during night time RED-STEADY BURNING LIGHT

 

MIOL-A,B or C should be used to lit extensive object (group of buildings or tree) or structure with 45 m < H ≤ 150 m 

Note: Medium intensity lights, type A and C should be used alone, whereas medium intensity lights, Type B should be used either alone or in combination with LIOL-B.

 

DUAL MEDIUM INTENSITY OBSTRUCTION LIGHT (MIOL)

  • Type AB WHITE FLASHING LIGHTflashing dual light(day time) RED FLASHING LIGHT (night time)
  • Type AC WHITE FLASHING LIGHTsteady dual light(day time) RED STEADY BURNING LIGHT (night time)

Where, in the opinion of the appropriate authority, the use of MIOL-A, at night may dazzle pilots in the vicinity of an aerodrome (within  approximately 10 000 m radius) or cause significant environmental concerns, a dual obstacle lighting system should be provided.

This system should be composed of medium-intensity obstacle lights, Type A, as appropriate, for daytime and twilight use and medium-intensity obstacle lights, Type B or C, for night-time use.

 

HIGH INTENSITY OBSTRUCTION LIGHT (HIOL)

  • Type Aflashing white light(Intensity>200’000 cd) WHITE-FLASHING LIGHT
  • Type Bflashing white light(Intensity>100’000 cd) WHITE-FLASHING LIGHT

HIOL-A, should be used to indicate the presence of an object if its H > 150 m and an aeronautical study indicates such lights to be essential for the recognition of the object by day

HIOL-B, should be used to indicate the presence of a tower supporting overhead wires, cables, etc.

What to do if the obstacle is 45m or less?

Lighting of objects with a height less than 45m above ground level

According to ICAO Annex 14 Chapter 6  6.2.3.19 recommendation.

Low-intensity obstacle lights, Type A or B, should be used where the object is a less extensive one and its height above the surrounding ground is less than 45 m.

Is there a specific statement about chimney/stack in the regulation?

A chimney is a typical cylindrical and vertical structure that provides ventilation for hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere.

ICAO 6.3.12 says : In the case of chimney or other structure of like function, the top lights shall be placed sufficiently below the top so as to minimize contamination by smoke etc.

3 pcs aviation obstruction lights might be used for chimneys/stacks with circular base < 6m

4 pcs aviation obstruction lights might be used for chimneys/stacks with circular base > 6m

But If the diameter of chimney exceeds 31m, 6 pcs Aviation obstruction lights shall be used on the top.

Also If the diameter of chimney exceeds 61m, 8 pcs Aviation obstruction lights shall be used on the top.

*you can also check our applications page for more details.

How is the installation, feeding and maintenance of AWL system?

We provide a guidebook for customer to install the system properly regarding to our design. It includes drawings, cable details and any other important information which helps to installer.

Also, Operation and Maintenance Manual Book about aviation lighting system is released when the production process is done with customers. We are also able to guide you how to install the system.

How about the IP classification?

All Wetra lights are classified as IP65, IP66 or IP67. According to your request, IP degree can be increased.

Should we use AWL in day-time?

If structure is not marked and its height more than 45m, it shall be lighted during the daytime with a Aviation obstruction lights Type A which has candela at least 20.000 candela.