Narrative:

This report cites a recurring problem rather than a specific event. Occasionally, after a pilot makes a radio transmission, the microphone switch will remain keyed (stuck microphone). In an en route or approach control environment, this is unnerving at best and very dangerous at worst when dealing with numerous aircraft at conflicting altitudes. On the ground, this may cause delays which eventually affect traffic in the air. At present, the offending party is rarely aware of the stuck microphone, and the situation may exist for several mins, making the frequency virtually useless. Other pilots on that frequency are then at the mercy of their own common sense in taking appropriate action. This action is often to return to a previous frequency, which, although probably the best alternative, may provide an unnecessary workload on that sector. In order to bring a stuck microphone to a pilot's attention, a timed warning device could be built into or added onto aircraft radios. After a microphone has been keyed continually for a specified time (example: 30 seconds) a beep-style alarm sounds, alerting the pilot that the microphone is still keyed. If the pilot is in the midst of a lengthy transmission longer than the specified time, he/she merely 'clicks' the microphone switch quickly and continues transmitting, and the alarm is discontinued, but reset for another 30 seconds. Some new automobiles have a similar feature to warn that a directional signal has been left on, so this suggestion merely adapts existing technology.

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Original NASA ASRS Text

Title: CTLR SUGGESTS THAT ACFT MICROPHONES HAVE A TIMING DEVICE BUILT IN TO REDUCE STUCK MIKE PROBLEMS.

Narrative: THIS RPT CITES A RECURRING PROBLEM RATHER THAN A SPECIFIC EVENT. OCCASIONALLY, AFTER A PLT MAKES A RADIO XMISSION, THE MICROPHONE SWITCH WILL REMAIN KEYED (STUCK MIKE). IN AN ENRTE OR APCH CTL ENVIRONMENT, THIS IS UNNERVING AT BEST AND VERY DANGEROUS AT WORST WHEN DEALING WITH NUMEROUS ACFT AT CONFLICTING ALTS. ON THE GND, THIS MAY CAUSE DELAYS WHICH EVENTUALLY AFFECT TFC IN THE AIR. AT PRESENT, THE OFFENDING PARTY IS RARELY AWARE OF THE STUCK MIKE, AND THE SITUATION MAY EXIST FOR SEVERAL MINS, MAKING THE FREQ VIRTUALLY USELESS. OTHER PLTS ON THAT FREQ ARE THEN AT THE MERCY OF THEIR OWN COMMON SENSE IN TAKING APPROPRIATE ACTION. THIS ACTION IS OFTEN TO RETURN TO A PREVIOUS FREQ, WHICH, ALTHOUGH PROBABLY THE BEST ALTERNATIVE, MAY PROVIDE AN UNNECESSARY WORKLOAD ON THAT SECTOR. IN ORDER TO BRING A STUCK MIKE TO A PLT'S ATTN, A TIMED WARNING DEVICE COULD BE BUILT INTO OR ADDED ONTO ACFT RADIOS. AFTER A MICROPHONE HAS BEEN KEYED CONTINUALLY FOR A SPECIFIED TIME (EXAMPLE: 30 SECONDS) A BEEP-STYLE ALARM SOUNDS, ALERTING THE PLT THAT THE MICROPHONE IS STILL KEYED. IF THE PLT IS IN THE MIDST OF A LENGTHY XMISSION LONGER THAN THE SPECIFIED TIME, HE/SHE MERELY 'CLICKS' THE MICROPHONE SWITCH QUICKLY AND CONTINUES XMITTING, AND THE ALARM IS DISCONTINUED, BUT RESET FOR ANOTHER 30 SECONDS. SOME NEW AUTOMOBILES HAVE A SIMILAR FEATURE TO WARN THAT A DIRECTIONAL SIGNAL HAS BEEN LEFT ON, SO THIS SUGGESTION MERELY ADAPTS EXISTING TECHNOLOGY.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.