In the case of a
radio failure or
aircraft
An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...
not equipped with a radio, or in the case of a deaf pilot,
air traffic control
Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled air ...
may use a
signal lamp (called a "signal light gun" or "light gun" by the
FAA) to direct the aircraft.
ICAO regulations require air traffic control towers to possess such signal lamps.
The signal lamp has a focused bright beam and is capable of emitting three different colors: red, white and green.
These colors may be flashed or steady, and have different meanings to aircraft in flight or on the ground.
Planes can acknowledge the instruction by rocking their wings, moving the
ailerons if on the ground, or by flashing their landing or navigation lights during hours of darkness.
Air traffic control signal light guns are typically specified with a (white) center beam brightness of > 180,000 - 200,000 candela,
and are visible for roughly 4 miles in clear daylight conditions.
The table below describes the meaning of the signals.
The use of handheld combination red/green/white signal lamps for air traffic control dates back to at least the 1930s.
See also
*
Navigation light
*
Formation light
*
Landing light
References
{{Reflist
Airport infrastructure
Aviation communications
Air traffic control
Optical communications