Communication failures can arise from a number of sources: Equipment Failure, Radio interference, Radio black holes, language barrier. Pilots are expected to exercise good judgement when confronted with radio communication problem. They may deviate from the rules to the extent required to meet an emergency. The pilots usually try one of more the following scenarios to correct the situation.

Incorrect Frequency

As planes fly towards their destination, they are handed over from one sector to other. When the plane is being handed over, the pilot is provided a new frequency to contact the new sector. If the pilot is unable to communicate over the new frequency, pilots switch back to the previous frequency and verify with the controller if they have the correct frequency for the new sector. If pilots are unable to establish communications with the previous controller as well, they continue flying as per the previous instruction given to them by the controller and all the while try establishing the communication to either Air Traffic Controller.

Relaying

At times the pilots may find other planes in the vicinity that are able to communicate with the controller. In these cases, the messages are relayed to the stricken plane by the pilots of these planes. Sometimes this help may arrive without asking as that plane is able to hear the stricken plane as well the controller and knows that the plane and ATC cannot communicate directly.

Transponder Code/ Squak

Pilots can change the transponder code to 7600 which mean “Lost Communications”. This should get the attention of the controllers and they will make for the plane ensuring all other traffic steers clear of the plane.

Signal Lamp

When controllers are unable to establish radio communications with an airplane, they may use the signal lamp to direct the aircraft. The signal lamp has a focused bright beam and is capable of emitting three different colours: Red, White and Green. These colors may be flashed or steady and have different meanings to aircraft in flight and on ground. Pilots can acknowledge the instruction by rocking their wings, moving the ailerons if on the ground, or by flashing their landing or navigation lights during low light conditions or at night.Air Traffic Control: Radio Communication Failure

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