Narrative:

Location: downwind dfw. En route, captain communication trouble lit-dfw. Captain not receiving. Speaker ok, transmit ok, first officer communication ok. During frequency change dfw by dfw approach lost both first officer and captain transmit and receive. Reset circuit breaker no help. At 6000 ft on downwind, nose-to-nose with the pattern, IFR very busy. Dirtied aircraft so as not to run over traffic, trying tower frequencys, approach frequencys, circuit breaker reset, etc. Very busy in the cockpit with our problem and other traffic. The downwind in the middle of an IFR arrival is not a good place to go no- communication. The captain, in a very busy state, said we have to let ATC know we have a no-communication, go ahead and enter the no-communication transponder code 7500. Insert spurious braintron here. Although a subtle difference between 7600 and 7500 it is nevertheless a large tactical error. We finally got first officer communication back, established communication with dfw tower, and they asked to verify 7500 transponder. Acknowledged and we were now VFR and could squawk 1200. At the same time the captain and first officer realized the mistake and advised tower we were all ok and required no special handling. The wheels of progress were already in motion for 7500. Advised ground and dispatch and tower all ok and called dfw tower system operation center who advised mod all ok 7500 entered for a no-communication situation. Captain takes full responsibility for error. It was an honest mistake in a very busy environment, but caused quite a stir. Much learned by first officer, and captain likely will not make again.

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Original NASA ASRS Text

Title: FLC INADVERTENTLY SQUAWKED XPONDER CODE 7500 IN ERROR AFTER EXPERIENCING A LOSS OF COMS WHILE DOWNWIND FOR LNDG. FLC WERE ABLE TO RE-ESTABLISH COM AND CANCEL THE ALERT ERROR.

Narrative: LOCATION: DOWNWIND DFW. ENRTE, CAPT COM TROUBLE LIT-DFW. CAPT NOT RECEIVING. SPEAKER OK, XMIT OK, FO COM OK. DURING FREQ CHANGE DFW BY DFW APCH LOST BOTH FO AND CAPT XMIT AND RECEIVE. RESET CIRCUIT BREAKER NO HELP. AT 6000 FT ON DOWNWIND, NOSE-TO-NOSE WITH THE PATTERN, IFR VERY BUSY. DIRTIED ACFT SO AS NOT TO RUN OVER TFC, TRYING TWR FREQS, APCH FREQS, CIRCUIT BREAKER RESET, ETC. VERY BUSY IN THE COCKPIT WITH OUR PROB AND OTHER TFC. THE DOWNWIND IN THE MIDDLE OF AN IFR ARR IS NOT A GOOD PLACE TO GO NO- COM. THE CAPT, IN A VERY BUSY STATE, SAID WE HAVE TO LET ATC KNOW WE HAVE A NO-COM, GO AHEAD AND ENTER THE NO-COM XPONDER CODE 7500. INSERT SPURIOUS BRAINTRON HERE. ALTHOUGH A SUBTLE DIFFERENCE BTWN 7600 AND 7500 IT IS NEVERTHELESS A LARGE TACTICAL ERROR. WE FINALLY GOT FO COM BACK, ESTABLISHED COM WITH DFW TWR, AND THEY ASKED TO VERIFY 7500 XPONDER. ACKNOWLEDGED AND WE WERE NOW VFR AND COULD SQUAWK 1200. AT THE SAME TIME THE CAPT AND FO REALIZED THE MISTAKE AND ADVISED TWR WE WERE ALL OK AND REQUIRED NO SPECIAL HANDLING. THE WHEELS OF PROGRESS WERE ALREADY IN MOTION FOR 7500. ADVISED GND AND DISPATCH AND TWR ALL OK AND CALLED DFW TWR SYS OP CTR WHO ADVISED MOD ALL OK 7500 ENTERED FOR A NO-COM SIT. CAPT TAKES FULL RESPONSIBILITY FOR ERROR. IT WAS AN HONEST MISTAKE IN A VERY BUSY ENVIRONMENT, BUT CAUSED QUITE A STIR. MUCH LEARNED BY FO, AND CAPT LIKELY WILL NOT MAKE AGAIN.

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.