Applies not only to aircraft, but to ground vehicles, equipment, and personnel not equipped with radios
ATC personnel use a directive traffic control signal which emits an intense narrow light beam of a selected color (either red, white, or green) when controlling traffic by light signals
Light Gun Procedures:
If radios go out in the terminal area, circle the field and wait for light gun signals
If no signals appear evident after a sufficient amount of time waiting, begin an approach when traffic has been determined and de-conflicted and land on the active runway (as dictated by traffic and wind) and look for light gun signals
If in the pattern and no light gun signals are observed, wave-off your first approach and continue in the pattern for a full stop
If radio malfunction occurs after departing the parking area, watching the tower for light signals or monitor tower frequency
Day Light Gun Procedures:
Rock your wings to get towers attention and acknowledge towers instructions or light signals by moving the ailerons or rudder
Night Light Gun Procedures:
At night, acknowledge by blinking the landing or navigation lights
Between sunset and sunrise, a pilot wishing to attract the attention of the control tower should turn on a landing light and taxi the aircraft into a position, clear of the active runway, so that light is visible to the tower
The landing light should remain on until appropriate signals are received from the tower
Notes:
A green light means you are cleared to land on any runway
Signals can be difficult to see during the day, especially if you're trying to fly and look at the tower [Video 1]
At night, light signals as you can imagine are easy to see, but from towers point of view, you may not
Complicating matters, if you have an electrical issue causing your inability to communicate, you may not have working lights either
Disadvantages:
Pilots may not be looking at the control tower at the time a signal is directed toward their aircraft
The directions transmitted by a light signal are very limited since only approval or disapproval of a pilot's anticipated actions may be transmitted
No supplement or explanatory information may be transmitted except by the use of the "General Warning Signal" which advises the pilot to be on alert
Private Pilot (Airplane) Communications, Light Signals, and Runway Lighting Systems Airman Certification Standards:
Objective: To determine the applicant exhibits satisfactory knowledge, risk management, and skills associated with normal and emergency radio communications, air traffic control (ATC) light signals, and runway lighting systems
Although the traffic signal light offers the advantage that some control may be exercised over nonradio equipped aircraft, pilots should be cognizant of the disadvantages