For US student pilots
Light gun signals and radio failure
When the radio dies, the tower still has a way to talk to you: a light gun, and six signals whose meanings change depending on whether you are on the ground or in the air. Every private pilot checkride asks about them, and the day you need them is not the day to look them up.
Here are the signals, how to acknowledge one, and what the AIM says to do first when the receiver goes quiet.
Light signals
The tower controls aircraft without a working radio by light gun. In daylight acknowledge by rocking the wings (in flight) or moving the ailerons or rudder (on the ground); at night by flashing the landing or navigation lights. [AIM 4-3-13, TBL 4-3-1]
- Steady green
- In flight: cleared to land. On the ground: cleared for takeoff.
- Flashing green
- In flight: return for landing (a steady green will follow). On the ground: cleared to taxi.
- Steady red
- In flight: give way to other aircraft and continue circling. On the ground: stop.
- Flashing red
- In flight: airport unsafe, do not land. On the ground: taxi clear of the runway in use.
- Flashing white
- On the ground: return to your starting point on the airport.
- Alternating red and green
- Exercise extreme caution.
Radio failure
- Squawk 7600
- And, in VFR conditions, continue VFR and land as soon as practicable — which is not “as soon as possible”, nor at an unsuitable airport. [AIM 6-4-1 c 2]
- Receiver failed, arriving at a towered airport
- Stay outside or above the Class D until you have worked out the traffic flow; then transmit in the blind — type, position, altitude, intention to land, request light signals — and at 3 to 5 miles announce your position and join the pattern, watching the tower. [AIM 4-2-13 a 1]
- Transmitter failed (or both)
- Stay outside or above the Class D until the flow is known, join the pattern, monitor the tower frequency and watch for light signals; acknowledge by rocking the wings. [AIM 4-2-13 a 2, 3]
- Departing with a failed radio
- Have it fixed; otherwise telephone the tower for authorisation to depart without two-way radio. [AIM 4-2-13 b]
Practice the day it goes wrong
TowerTalk's Exercise G is the non-standard situations: the calls that are not in the script, at a real US airport, graded with the AIM paragraph.
Related
Study aid, written in our own words from the FAA Aeronautical Information Manual (Change 3, 7/9/26) and the Pilot/Controller Glossary, with paragraph references so you can check each point. Last reviewed 9 September 2026; awaiting review by a US flight instructor. It does not reproduce those documents and is not a substitute for them — always defer to the AIM, the current FAA publications, your instructor and your examiner. TowerTalk is not approved or endorsed by the FAA.