Communication failure procedures and lost-comm
This section covers communication failure procedures and lost-comm: what to do when you can transmit but not receive, receive but not transmit, or lose both, and how to interpret light signals.
Core rules
- For two-way radio failure, squawk 7600, try alternate frequencies and check headset, volume, squelch and circuit breakers.
- In visual meteorological conditions, continue under VFR and land at the nearest suitable aerodrome; in instrument conditions, follow the last assigned clearance or the filed flight plan and listen on 121.5.
- Watch for light-gun signals from the tower. In flight: steady green means cleared to land; flashing green means return for landing; steady red means give way and continue circling; flashing red means aerodrome unsafe, do not land; alternating red and green means exercise extreme caution.
- On the ground: steady green means cleared for take-off; flashing green means cleared to taxi; steady red means stop; flashing red means taxi clear of the runway in use.
Worked example
A pilot loses radio in VMC while approaching a controlled aerodrome and squawks 7600. The tower gives a steady green light. The pilot is cleared to land because steady green, in flight, means “cleared to land”. The pilot should still watch for other traffic and avoid assuming that the light signal authorises anything beyond landing.
Traps
Squawking 7700 instead of 7600; assuming lost-comm always means an emergency; not trying a second radio or headset; and misreading a flashing red light as clearance to land.