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 even a structure which in height is 150mtr or higher, requires visual marking with aircraft warning lights.

What are the different types of aircraft warning lights?

Here are three main types of aircraft warning lights which are used; these are:

  • High IntensityThe High intensity is a Type A (white flashing) aircraft warning light with an output intensity of 200,000candela during the day, 20,000candela at twilight and 2,000candela during the night.
  • Medium IntensityThe Medium intensity comes in 3 different types.
    • Type A – white flashing 20,000candela
    • Type B – red flashing 2,000candela
    • Type C – red steady burning 2,000candela
  • Low IntensityThe Low intensity light is a constant red light (steady burning), and however comes as a 10candela, 20candela, 32candela and a 200candela light intensity, an optional

What type of lights do I need?

Structures with a height less than 45mtr require low intensity lights

Structures with a height of 45mtr or higher require medium intensity lights.

Structures with a height greater than 150mtr require high intensity lights – 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.

LEDs have many advantages such as:

  • 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 together 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.

The LED also has disadvantages:

  • 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 which 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 color light as the bulbs only give out a white light which only comes as a flashing type and not steady burning.

Below 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 a small bulb but with high power output
  • Power – The xenon a light consume less power than an incandescent bulb but produces more light.

Disadvantages of a Xenon aircraft warning light:

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

What is FluorescentLighting?

Fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. 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.

Advantages of a fluorescent light:

  • 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.

And 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.

Advantages of a fluorescent light:

  • Cost Effective – bulbs are easy to purchase and cheaper then 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 faulty bulb

And disadvantages of a fluorescent 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