Narrative:

After departure from detroit metropolitan airport, radio failure occurred with departure control for approximately 2-4 mins. Contact with departure control was established cause of the radio failure was not determined. Flight was cleared on course. Approximately 3 mins later radio contact was lost again. Through sfo arinc a frequency for cle center was received and contact with cle center was successful. Clearance to destination was received. En route once again radio contact was lost. Followed lost communication procedures, squawked 7700 for one min then 7600. All radios including VOR navigation receivers were utilized for reception and transmission. Radio contact with chicago center was established and contact with ATC was continuous thereafter and no further radio failure occurred. The capts pendant switch was suspected to have caused a hot microphone blocking reception on the #1 UHF receiver. The problem was intermittent. The capts pendant switch was disconnected and the hand-held microphone was used in its place which contributed to establishing radio contact. A hot microphone is difficult to determine and is compounded if the problem is intermittent. The capts pendant switch could be heard audibly clicking on and off lessening the determination that the switch was sticking in the on position causing a hot microphone. Setting up radio #1 and radio #2 on separate frequencys and separately selecting the transmission switch from the captain and coplts position may aid in clearing the stuck microphone (or isolating the stuck microphone). A crew should be on alert for a stuck microphone as there's no indication to the crew other than loss of reception. Xmissions are normal with audible side tones.

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Original NASA ASRS Text

Title: LGT FLT DEPARING DTW HAD DIFFICULTY CONTACTING ZOB AND ZAU. ATC ADVISED THEY HAD A STUCK MICROPHONE.

Narrative: AFTER DEP FROM DETROIT METRO ARPT, RADIO FAILURE OCCURRED WITH DEP CTL FOR APPROX 2-4 MINS. CONTACT WITH DEP CTL WAS ESTABLISHED CAUSE OF THE RADIO FAILURE WAS NOT DETERMINED. FLT WAS CLRED ON COURSE. APPROX 3 MINS LATER RADIO CONTACT WAS LOST AGAIN. THROUGH SFO ARINC A FREQ FOR CLE CTR WAS RECEIVED AND CONTACT WITH CLE CTR WAS SUCCESSFUL. CLRNC TO DEST WAS RECEIVED. ENRTE ONCE AGAIN RADIO CONTACT WAS LOST. FOLLOWED LOST COM PROCS, SQUAWKED 7700 FOR ONE MIN THEN 7600. ALL RADIOS INCLUDING VOR NAV RECEIVERS WERE UTILIZED FOR RECEPTION AND XMISSION. RADIO CONTACT WITH CHICAGO CTR WAS ESTABLISHED AND CONTACT WITH ATC WAS CONTINUOUS THEREAFTER AND NO FURTHER RADIO FAILURE OCCURRED. THE CAPTS PENDANT SWITCH WAS SUSPECTED TO HAVE CAUSED A HOT MIC BLOCKING RECEPTION ON THE #1 UHF RECEIVER. THE PROB WAS INTERMITTENT. THE CAPTS PENDANT SWITCH WAS DISCONNECTED AND THE HAND-HELD MIC WAS USED IN ITS PLACE WHICH CONTRIBUTED TO ESTABLISHING RADIO CONTACT. A HOT MIC IS DIFFICULT TO DETERMINE AND IS COMPOUNDED IF THE PROB IS INTERMITTENT. THE CAPTS PENDANT SWITCH COULD BE HEARD AUDIBLY CLICKING ON AND OFF LESSENING THE DETERMINATION THAT THE SWITCH WAS STICKING IN THE ON POS CAUSING A HOT MIC. SETTING UP RADIO #1 AND RADIO #2 ON SEPARATE FREQS AND SEPARATELY SELECTING THE XMISSION SWITCH FROM THE CAPT AND COPLTS POS MAY AID IN CLRING THE STUCK MIC (OR ISOLATING THE STUCK MIC). A CREW SHOULD BE ON ALERT FOR A STUCK MIC AS THERE'S NO INDICATION TO THE CREW OTHER THAN LOSS OF RECEPTION. XMISSIONS ARE NORMAL WITH AUDIBLE SIDE TONES.

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.