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Aviation Learning Center Document Radio Communications Phraseology and Techniques - P-8740-47
Author: Federal Aviation Administration Date: revised April 2006
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Radio Malfunction Procedures
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Aircraft Radio Malfunctions

Inoperative Receiver. If you are approaching a towered airport and have reason to believe your transmitter works but your receiver is inoperative, remain outside or above the airport traffic area until you determine the direction and flow of traffic. Then you should advise the tower of your type aircraft, position, altitude, intention to land, and request that you be controlled with light signals (see below). When you are approximately 3 to 5 miles from the airport, advise the tower of your position and join the airport traffic pattern. From this point on, watch the tower for light signals. Thereafter, if a complete pattern is made, transmit your position downwind and/or turning base leg.

Inoperative Transmitter. If you are approaching a towered airport and have reason to believe your receiver works but your transmitter is inoperative, remain outside or above the airport traffic area until you can determine the direction and flow of traffic, then join the airport traffic pattern. Monitor the primary local control frequency as depicted on Sectional Charts for landing or traffic information, and look for a light signal addressed to your aircraft. During daylight hours, acknowledge tower transmissions or light signals be rocking your wings. At night, acknowledge by blinking the landing or navigation lights.

Inoperative Transmitter and Receiver. If you are approaching a towered airport and have reason to believe that your transmitter and receiver are both inoperative, remain outside or above the airport traffic area until you can determine the direction and flow of traffic. Then join the airport traffic pattern and maintain visual contact with the tower to receive light signals. During daylight hours, acknowledge tower transmissions or light signals by moving the ailerons or rudder. At night, acknowledge by blinking the landing or navigation lights.

If you experience radio failure prior to leaving the aircraft parking area, make every effort to have the equipment repaired. If you are unable to have the malfunction repaired, it is possible in some areas to call the tower by telephone and request authorization to depart without two-way radio communications. (Note: This procedure would not be authorized in areas such as the Washington DC Air Defense Identification Zone, or ADIZ, where two-way communications are required at all times. If the tower grants your request, you will receive departure information and instructed to monitor the tower frequency or watch for light signals, as appropriate. During daylight hours, acknowledge tower transmissions or light signals by moving the ailerons or rudder. At night, acknowledge by blinking the landing or navigation lights.

If radio malfunction occurs after departing the aircraft parking area (i.e., on the taxiway), watch the tower for light signals or monitor tower frequency. Note: Refer to 14 CFR 91.87 and 14 CFR 91.77 for additional information..

Light Gun Signals

An airport control tower uses the following procedures to issue control instructions to aircraft not equipped with radio, or those with inoperative 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.

Although the traffic signal light offers the advantage that some control may be exercised over nonradio ("NORDO") aircraft, pilots should be aware of the following disadvantages.

  • The pilot may not be looking at the control tower at the time a signal is directed toward him.
  • 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 the alert.

Between sunset and sunrise, a "NORDO" pilot on the ground seeking 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 the landing light is visible to the tower. The landing light should remain on until appropriate signals are received from the tower.

During daylight hours, acknowledge tower transmissions or light signals by moving the ailerons or rudder. At night, acknowledge by blinking the landing or navigation lights. If a radio malfunction occurs after departing the parking area, watch the tower for light signals or monitor tower frequency.

The following table summarizes light gun signals.

used for alignment Light Gun Signals used for alignment
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used for alignment Type  Color  Meaning-On Ground  Meaning-In Flight used for alignment
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used for alignment Steady  Green  Cleared for Takeoff  Cleared to Land used for alignment
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used for alignment Steady  Red  Stop  Give Way/Circle used for alignment
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used for alignment Flashing  Green  Cleared to Taxi  Return for Landing used for alignment
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used for alignment Flashing  Red  Taxi Clear of Landing Area  Airport Unsafe-Do Not Land used for alignment
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used for alignment Flashing  White  Return to Starting Point  Not Applicable used for alignment
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used for alignment Alternating  Red/Green  Use Extreme Caution  Use Extreme Caution used for alignment
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ATC Radio Outages

ARTCCs normally have at least one back up radio receiver and transmitter system for each frequency which can usually be placed into service quickly with little or no disruption of ATC service. Occasionally, technical problems may cause a delay but switchover seldom takes more than 60 seconds. When it appears that the outage will not be quickly remedied, the ARTCC will usually request a nearby aircraft, if there is one, to switch to the affected frequency to broadcast communications instructions. It is important, therefore. that the pilot wait at least one minute before deciding that the ARTCC has actually experienced a radio frequency failure. When such an outage does occur. the pilot should, if workload and equipment capability permit, maintain a listening watch on the affected frequency while attempting to comply with the following recommended communications procedures.

  • If two-way communications cannot be established with the ARTCC after changing frequencies, a pilot should attempt to recontact the transferring controller for the assignment of an alternative frequency or other instructions.
  • When an ARTCC radio frequency failure occurs after two-way communications have been established, the pilot should attempt to reestablish contact with the center on any other known ARTCC frequency, preferably that of the next responsible sector when practicable, and ask for instructions. When the next normal frequency change along the route is known to involve another ATC facility, the pilot should contact that facility, if feasible, for instructions. If communications cannot be reestablished by either method, the pilot is expected to request communications instructions from the FSS appropriate to the route of flight.

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