Aviation lighting is essential in keeping everyone safe; it ensures that building and objects can be seen in low light as well as helping both the pilot and air traffic controller communicate on landing in the form of light signals. In case of communication failure or when an aircraft isn’t equipped with a radio, light signals are used using a signal lamp. Signal lamps have focused bright beams that can generate red, white and green lights which can be steady or flashing. Each of these colours and patterns are instructions for aircraft pilots and have a specific meaning, depending whether the aircraft is in flight or on the ground. The aircraft pilot must recognize both the colour and pattern (steady or flashing) to properly decode the message from the control tower. Aircraft pilots can acknowledge these instructions by rocking the aircraft wings, moving the ailerons, or by flashing their navigation lights.
Aviation Light Signal Colours and their meanings
Just like a traffic light, aviation light signals use three different colours. However, instead of red, green and amber, used by road traffic signals, the Air Traffic Control light signals use the colours red, green and white. As mentioned above, each of these colours have a specific meaning and vary depending whether the aircraft is in flight or on the ground.
Aviation Light Signals on the Ground
Steady Green Light – The steady green light signal on the ground means the aircraft is cleared for takeoff and the pilot may proceed for takeoff.
Flashing Green – The flashing green light signal on the ground means that the aircraft is cleared or authorized to taxi.
Steady Red – The steady red light means the aircraft must stop immediately and hold their position.
Flashing Red –The flashing red light means the aircraft must taxi clear of the runway in use or get off the runway. The air traffic controller wants the aircraft pilot to find the nearest taxiway and get off the runway to allow other aircraft to use the runway.
Flashing White – The flashing white signal means the aircraft pilot must return to their starting point. The air traffic controller wants the pilot to return to the airport parking apron.
Alternating Red/Green – In countries such as the United States, the alternating red/green signal light means an important warning to the aircraft pilot to exercise extreme caution.
Aviation Light Signals in the Air
Steady Green – Green signal lights always indicate a GO. This means the aircraft is cleared to land.
Flashing Green – The flashing green light signal to an aircraft in flight means the aircraft should return for landing and is essentially a Go-Around command. The aircraft do not have a clearance to land, so the aircraft must return for landing via Go-Around.
Steady Red – Red light signals always indicate a stop command. However, an aircraft in flight is impossible to stop. So red light signal for an aircraft in flight means, the aircraft must continue circling and give way to other aircraft until the air traffic controller indicates that you are cleared to land by giving a steady green light.
Flashing Red – A Flashing Red light signal to an aircraft in flight indicates danger, the airport is unsafe and do not land.
Alternating Red/Green –Alternating Red/Green light signal applies to both aircraft on the ground and in flight. It indicates the aircraft pilot to exercise extreme caution.
Light signals are rarely used today by aircraft pilots because of the presence of radio for communication. However, radios are not always reliable and sometimes stop working. In times of communication failure, this will come in handy and is really important for aircraft navigation. An aircraft pilot will have the need to fall back on Aviation Light Signals for communication in order to avoid accident and ensure safety.
Communication is also key between the pilot and obstacles along his flight path – such as high buildings, masts, towers etc. To alert the pilot to the danger of these, warning beacon lamps are added to tall objects. The use of such lighting is intended to reduce hazards to aircraft by indicating the presence of obstacles.
The presence of objects which must be lighted, should be indicated by low, medium or high intensity obstacle warning light, or a combination of such lights.
Fixed obstacles of 45m or less in height, width and length are normally lit by a single, steady, red light, placed at the highest practicable point. Obstacles of greater size are normally provided with additional red lights in order to outline the extent of the building.
D.G. Controls offer a range of Type-A and Type-B Beacons that meet ICAO Annex 14, Chapter 6 requirements for Low Intensity Obstruction Warning and can be found at:
https://beaconlamps.com/products/visual-warning-signals/i.c.a.o.-warning-signals/