Air carrier widebody transport communication poblem due to stuck microphone.

Attributes
ACN	182959
Time
Date	199107
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : sfo
State Reference	CA
Altitude	msl bound lower : 29000 msl bound upper : 29000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : rjtg
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 4 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : other oceanic enroute : pacific enroute other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : atp
ASRS Report	182959
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

The second officer's microphone on this aircraft is located at a position just forward of his audio selector panel, however on other widebody transport's this hand microphone is located on the forward edge of the second officer's table. On two occasions during this flight, complete communications blockage with tokyo control and many nearby aircraft occurred. We did not realize it was our aircraft causing the problem until noticing the first officer's seat was backed fully aft and the life jacket in his back seat pocket was pressing squarely onto the second officer's microphone button. The instant the first officer slid his seat forward, the stuck microphone problem ceased. This can be a difficult problem to resolve especially if the second officer had not used his hand microphone for some time and after he did use it communication remained normal. Then the simple sliding aft of the first officer's seat is not easily connected with such a stuck microphone situation. Suggest all our widebody transport second officer hand mics be relocated to the forward table location to alleviate such possible communication failure problems.

Original NASA ASRS Text

Title: ACR WDB COM POBLEM DUE TO STUCK MIC.

Narrative: THE S/O'S MIC ON THIS ACFT IS LOCATED AT A POS JUST FORWARD OF HIS AUDIO SELECTOR PANEL, HOWEVER ON OTHER WDB'S THIS HAND MIC IS LOCATED ON THE FORWARD EDGE OF THE S/O'S TABLE. ON TWO OCCASIONS DURING THIS FLT, COMPLETE COMS BLOCKAGE WITH TOKYO CTL AND MANY NEARBY ACFT OCCURRED. WE DID NOT REALIZE IT WAS OUR ACFT CAUSING THE PROB UNTIL NOTICING THE F/O'S SEAT WAS BACKED FULLY AFT AND THE LIFE JACKET IN HIS BACK SEAT POCKET WAS PRESSING SQUARELY ONTO THE S/O'S MIC BUTTON. THE INSTANT THE F/O SLID HIS SEAT FORWARD, THE STUCK MIC PROB CEASED. THIS CAN BE A DIFFICULT PROB TO RESOLVE ESPECIALLY IF THE S/O HAD NOT USED HIS HAND MIC FOR SOME TIME AND AFTER HE DID USE IT COM REMAINED NORMAL. THEN THE SIMPLE SLIDING AFT OF THE F/O'S SEAT IS NOT EASILY CONNECTED WITH SUCH A STUCK MIC SITUATION. SUGGEST ALL OUR WDB S/O HAND MICS BE RELOCATED TO THE FORWARD TABLE LOCATION TO ALLEVIATE SUCH POSSIBLE COM FAILURE PROBS.

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.