Aircraft Warning Lights FAQs

Here we have collated the most commonly asked Aircraft Warning Lights FAQs we come accross. If you can’t find the answer you are looking for then do not hesitate to contact us.

What is the meaning of AWL?

AWL is an abbreviation of the word “Aircraft warning light”.

Do I need aircraft warning lights?

Any structure in a flight path or especially a structure that has a height of 150m or higher requires visual marking with aircraft warning lights.

What are the different types of aircraft warning lights?

Three main types of aircraft warning lights are used; these are high intensity, medium intensity and low intensity.

What are high intensity warning lights?

High intensity warning lights are a Type A (white flashing) aircraft warning light with an output intensity of 200,000cd during the day, 20,000cd at twilight and 2,000cd at night-time.

What are medium intensity warning lights?

Medium intensity warning lights come in 3 different beacon variations, depending on the height and situation of the structure.

  • Type A – white flashing 20,000cd during the day, 2,000 at night-time.
  • Type B – red flashing 2,000cd at night-time.
  • Type C – red steady burning 2,000cd at night-time.

What are low intensity warning lights?

Low intensity warning lights are a constant red light (steady burning). Low intensity warning lights come as 10cd, 20cd, 32cd and 200cd.

Why do tower lights change from red to white?

Red and white aircraft warning lights are acceptable and required to help pilots avoid tower collisions. Most of the time, white lights are used during the daytime and red mostly at night. Many aircraft warning lights are connected to a control device that can adjust automatically in relation to sky illumination.

At what height are aircraft warning lights required?

Structures with a height less than 45 metres require low intensity lights.

For structures with a height of 45m or higher, these require medium intensity lights.

Structures with a height greater than 150m require high intensity lights – as recommended by the ICAO Annex 14.

What is LED Lighting?

Different types of lighting can be used to manufacture an aircraft warning light these are LED (light emitting diode), incandescent bulbs and xenon tubes.

LED technology is the latest of the three, LEDs create light through a “cold process”, when power is applied to semiconductors they’re stimulated by the movement of electrons; thus creating photons, the light that is visibly seen by us.

What are the advantages of LED lighting for aircraft warning lights?

  • High efficiency – LEDs can last up to 100,000hrs
  • Colour – LEDs come in various colours without any separate lenses
  • Size – LEDs are very small and can easily be grouped on a PCB (printed circuit board)
  • Shock resistance – LEDs, being solid state components, are difficult to damage with external shock
  • Toxicity: LEDs do not contain mercury, unlike fluorescent lamps.

Are there any disadvantages of LED lights for use as aircraft warning lights?

  • High initial price – LEDs are currently more expensive, price per lumen, on an initial capital cost basis, than most conventional lighting technologies.
  • Temperature dependence – LED performance largely depends on the ambient temperature of the operating environment. Over-driving the LED in high ambient temperatures may result in overheating of the LED package, eventually leading to device failure
  • Area light source: LEDs do not approximate a “point source” of light, but rather a distribution. So, LEDs are difficult to use in applications requiring a spherical light field.

What is Xenon Lighting?

Another relatively new type of lighting is the Xenon bulbs which consist of a gas that occurs in the Earth’s atmosphere. Xenon bulbs produce more light with less energy cost than some other lights, and the bulbs themselves have a much longer lifetime, therefore being cost-efficient than some incandescent & fluorescent bulbs. In aircraft warning lights Xenon bulbs are used along with filter lenses to create a red, green or a different colour light as the bulbs only give out a white light which only comes as a flashing type and not steady burning.

What are some of the advantages of having Xenon light?

  • Lifetime – The xenon gas in some bulbs can last up to 10 years
  • Size – the xenon bulb is small but with a high power output
  • Power – The xenon a light consumes less power than an incandescent bulb but produces more light.

What are the disadvantages of a Xenon aircraft warning light?

  • Colour – Only comes in white, external filters and lenses necessary for different colours
  • Characteristics – only available as a flashing light, no steady burning facility
  • Price – More expensive than incandescent and fluorescent lights.

What is Fluorescent Lighting?

A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapour. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful light more efficiently than an incandescent lamp. Lower energy cost typically offsets the higher initial cost of the lamp.

What are the advantages of fluorescent lighting used as aircraft warning lights?

  • Luminous efficiency – Fluorescent lamps convert more of the input power to visible light than incandescent lamps
  • Life – Typically a fluorescent lamp will last between 10 to 20 times as long as an equivalent incandescent lamp when operated several hours at a time
  • Lower heat – About two-thirds to three-quarters less heat is given off by fluorescent lamps compared to an equivalent installation of incandescent lamps.

What are the disadvantages of a fluorescent light?

  • Frequent switching – If the lamp is installed where it is frequently switched on and off, it will age rapidly. Under extreme conditions, its lifespan may be much shorter than a cheap incandescent lamp
  • Safety issues – If a fluorescent lamp is broken, a very small amount of mercury can contaminate the surrounding environment
  • Operating temperature – Fluorescent lamps operate best around room temperature. At much lower or higher temperatures, efficiency decreases

What is Incandescent Lighting?

Incandescent bulb/lamp is the oldest type of lighting around being used for aircraft warning lights. The incandescent bulb is a source of electric light that works by incandescence. An electric current passes through a thin filament, heating it to a temperature that produces light. The enclosing glass bulb contains either a vacuum or an inert gas to prevent oxidation of the hot filament.

What are the advantages of incandescent light?

  • Cost-effective – bulbs are easy to purchase and cheaper than LED lights
  • Power – Incandescent lights come in many wattages, and they require no special equipment to operate
  • Dimming – Incandescent lights can be dimmed by reducing the voltage that reaches them
  • Simple to replace the faulty bulb

What are the disadvantages of incandescent light?

  • Least energy efficient
  • Produce large amounts of heat as a by-product – approximately 90% of the energy produced is released in the form of heat and only 10% is light.
  • Shorter lives than most other lighting methods
  • Shock resistance – some movement can cause the filament inside to break failing the light

Remember, if your query is not listed on our aircraft warning lights FAQs page then contact us and we’ll have the answer for you.


Cd = candela. A candela is a unit of measurement of luminous intensity.

M = metre.

ICAO = International Civil Aviation Authority.