NORDO
NORDO (no radio) refers to an aircraft operating without functioning radio communications. A NORDO aircraft in controlled airspace must follow specific lost communications procedures and ATC will use light gun signals to control the aircraft.
Light Gun Signals
- Steady green: Cleared to land (in air) / Cleared to taxi (on ground)
- Flashing green: Return for landing (in air) / Cleared to taxi to active runway (on ground)
- Steady red: Give way — continue circling (in air) / Stop (on ground)
- Flashing red: Airport unsafe, do not land (in air) / Taxi clear of runway in use (on ground)
- Flashing white: Return to starting point on airport (on ground)
- Alternating red and green: Exercise extreme caution
NORDO Procedures
If radio communication is lost while airborne: squawk 7600; if VMC, land at the nearest suitable airport with a tower; if IMC, comply with the lost communications procedure for IFR flight. Tower will watch for light gun acknowledgements (rock wings in flight, flash landing/taxi lights on ground).
On the TC Written Exam
Light gun signals are a standard exam topic. Know all six signals and their meanings for both air and ground.
Related Terms
See also: Transponder Codes, Control Tower.