A B737-700 first officer's push to talk microphone switch stuck in the transmit position blocking th...

Narrative:

First officer's push to talk (ptt) switch became stuck in the transmit position. First officer thought he was hearing himself through his headset but knew that the ptt switch was in the off (neutral position). He verified that the switch was in the neutral position and asked me if I had heard him. I had heard him through my headset. He cycled the ptt switch to get it to stop transmitting. About 10 seconds later; ATC asked if we were on frequency. We had discussed the possibility of a stuck mic during crew briefing because there are reports that this is occurring frequently. The last communication that we received from company flight operations declared that the switch was not the problem and could not be the problem. I've talked with several mechanics that have told me that the failure rate of this switch is much higher than the previous switch that we used. If this is indeed the case; it would be proper for a correction and clarification as to what the problem might/could be so that better vigilance could be demonstrated by flight crews until such a time as a fix can be made. This is an extreme safety issue. It's not if; but when; another company aircraft's communication is compromised which could result in the crew being unable to communicate with ATC.

Original NASA ASRS Text

Title: A B737-700 First Officer's push to talk microphone switch stuck in the transmit position blocking the ATC frequency; repeated switch activation returned it to OFF.

Narrative: First Officer's Push to Talk (PTT) switch became stuck in the transmit position. First Officer thought he was hearing himself through his headset but knew that the PTT switch was in the off (neutral position). He verified that the switch was in the neutral position and asked me if I had heard him. I had heard him through my headset. He cycled the PTT switch to get it to stop transmitting. About 10 seconds later; ATC asked if we were on frequency. We had discussed the possibility of a stuck mic during crew briefing because there are reports that this is occurring frequently. The last communication that we received from Company Flight Operations declared that the switch was not the problem and could not be the problem. I've talked with several Mechanics that have told me that the failure rate of this switch is much higher than the previous switch that we used. If this is indeed the case; it would be proper for a correction and clarification as to what the problem might/could be so that better vigilance could be demonstrated by flight crews until such a time as a fix can be made. This is an extreme safety issue. It's not if; but when; another Company aircraft's communication is compromised which could result in the crew being unable to communicate with ATC.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	975638
Time
Date	201110
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Air/Ground Communication
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 180
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Maintenance

A B737-700 first officer's push to talk microphone switch stuck in the transmit position blocking the ATC frequency; repeated switch activation returned it to off.