Narrative:

Upon departure first officer flying, captain on radio, captain attempted contact with msp departure on 120.0 with no response. Also attempted all other radios, ground frequency and tower frequency with no response. All radios from captain's control box were dead west/O side tone or any other indications. Captain and first officer exchanged duties and captain leveled at 5000' and runway heading as we had been instructed prior to takeoff. First officer attempted all frequencys on all radios and second officer checked all applicable circuit breaker's and radio master switches. First officer also checked VOR audio on msp VOR, emergency/normal switch on first officer's selector box and 121.5 on radio 1 and 2. All this took approximately 1-2 mins. First officer finally got departure on radio 2. Was told to climb to 7000' and given a turn to approximately 280 degrees. I told departure we were having extreme radio problems and abruptly lost communication again. First officer selected 7600 on transponder (no 7700 because departure already knew nature of problem). After more attempted we again made contact with departure and asked for and received a holding fix to dump fuel, EAC time, approach clearance, landing clearance, gate assignment and taxi clearance all at once, so we had a unifiled plan if we had lost communication again. We left all switches and radios alone and maintained communication to gate. After maintenance check found captain's microphone switch on yoke had shorted captain's radio panel, so it acted like he had a stuck microphone. First officer could transmit and receive on VHF 2 with captain's communication selector in VHF 3 position only. Any deviation from that confign resulted in no communication or receive on any radio frequency. One possible explanation is that ACARS uses radio 3 on this aircraft. After landing departure supervisor was contacted for critique and thanks for support. He liked our handling of situation and thought it went well, especially asking for all up to taxi clearance all at once so everyone knew exactly what would happen and with an EAC time, when it would. This reporter is filed for the maintenance information and any possible complications as yet unknown. Supplemental information from acn 180272: conflict could have resulted because msp SID lacks associated lost communication procedures. Msp should have standardized lost communication. Flight returned to msp.

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Original NASA ASRS Text

Title: EMERGENCY DECLARED AFTER INTERMITTENT COM ESTABLISHED IN LOST COM PROC.

Narrative: UPON DEP F/O FLYING, CAPT ON RADIO, CAPT ATTEMPTED CONTACT WITH MSP DEP ON 120.0 WITH NO RESPONSE. ALSO ATTEMPTED ALL OTHER RADIOS, GND FREQ AND TWR FREQ WITH NO RESPONSE. ALL RADIOS FROM CAPT'S CTL BOX WERE DEAD W/O SIDE TONE OR ANY OTHER INDICATIONS. CAPT AND F/O EXCHANGED DUTIES AND CAPT LEVELED AT 5000' AND RWY HDG AS WE HAD BEEN INSTRUCTED PRIOR TO TKOF. F/O ATTEMPTED ALL FREQS ON ALL RADIOS AND S/O CHKED ALL APPLICABLE CB'S AND RADIO MASTER SWITCHES. F/O ALSO CHKED VOR AUDIO ON MSP VOR, EMER/NORMAL SWITCH ON F/O'S SELECTOR BOX AND 121.5 ON RADIO 1 AND 2. ALL THIS TOOK APPROX 1-2 MINS. F/O FINALLY GOT DEP ON RADIO 2. WAS TOLD TO CLB TO 7000' AND GIVEN A TURN TO APPROX 280 DEGS. I TOLD DEP WE WERE HAVING EXTREME RADIO PROBS AND ABRUPTLY LOST COM AGAIN. F/O SELECTED 7600 ON XPONDER (NO 7700 BECAUSE DEP ALREADY KNEW NATURE OF PROB). AFTER MORE ATTEMPTED WE AGAIN MADE CONTACT WITH DEP AND ASKED FOR AND RECEIVED A HOLDING FIX TO DUMP FUEL, EAC TIME, APCH CLRNC, LNDG CLRNC, GATE ASSIGNMENT AND TAXI CLRNC ALL AT ONCE, SO WE HAD A UNIFILED PLAN IF WE HAD LOST COM AGAIN. WE LEFT ALL SWITCHES AND RADIOS ALONE AND MAINTAINED COM TO GATE. AFTER MAINT CHK FOUND CAPT'S MIC SWITCH ON YOKE HAD SHORTED CAPT'S RADIO PANEL, SO IT ACTED LIKE HE HAD A STUCK MIC. F/O COULD XMIT AND RECEIVE ON VHF 2 WITH CAPT'S COM SELECTOR IN VHF 3 POS ONLY. ANY DEVIATION FROM THAT CONFIGN RESULTED IN NO COM OR RECEIVE ON ANY RADIO FREQ. ONE POSSIBLE EXPLANATION IS THAT ACARS USES RADIO 3 ON THIS ACFT. AFTER LNDG DEP SUPVR WAS CONTACTED FOR CRITIQUE AND THANKS FOR SUPPORT. HE LIKED OUR HANDLING OF SITUATION AND THOUGHT IT WENT WELL, ESPECIALLY ASKING FOR ALL UP TO TAXI CLRNC ALL AT ONCE SO EVERYONE KNEW EXACTLY WHAT WOULD HAPPEN AND WITH AN EAC TIME, WHEN IT WOULD. THIS RPTR IS FILED FOR THE MAINT INFO AND ANY POSSIBLE COMPLICATIONS AS YET UNKNOWN. SUPPLEMENTAL INFO FROM ACN 180272: CONFLICT COULD HAVE RESULTED BECAUSE MSP SID LACKS ASSOCIATED LOST COM PROCS. MSP SHOULD HAVE STANDARDIZED LOST COM. FLT RETURNED TO MSP.

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.