Narrative:

Approaching egpf talking to glasgow radar, expecting runway 23 (already briefed and configured), radar vectors descending to 4000 ft, heading northeast, IMC, WX at gla good: 5 KM visibility, 2000 ft broken, wind 5 KTS, captain is PF, first officer is PNF. Instructed to turn left to 185 degree heading, runway change to runway 5, visibility midfield 700 ft with low level fog. Due to WX change, we now begin briefing and setting up for a monitored approach. Both of us are having trouble understanding controller. We keep asking him to repeat. We are very busy at this point with briefing, and both of us hear controller issue clearance to descend to 3000 ft. First officer reads back clearance, 3000 ft is confirmed set in altitude window by both pilots, and we descend to 3000 ft. Controller then said, 'confirm level at 4000 ft.' first officer replies, 'negative, level at 3000 ft as assigned.' controller says, 'ok, just stay at 3000 ft.' we contacted glasgow controllers by phone on the ground, and after listening to tapes, determined that clearance was for another air carrier and both of us answered the clearance at exactly the same time. On tape it was garbled, but ended with audible,'...X,' the last number of our call sign. Controller did not ask for clarification of who answered clearance, and we did not know we had answered someone else's clearance. ATC supervisor admitted late runway change may have added to confusion. It certainly increased our workload, which was already increased due to the fog WX change, and was questionable with such light winds. Responsibility lies with both us and controller. We mistook and answered someone else's clearance (due to our high workload) and controller for not clarifying readback when it was obviously garbled and ended with '...X,' not '...Y.'

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Original NASA ASRS Text

Title: 2 ACFT ACCEPT THE SAME CLRNC WITH SIMULTANEOUS REPLY IN FOREIGN OP.

Narrative: APCHING EGPF TALKING TO GLASGOW RADAR, EXPECTING RWY 23 (ALREADY BRIEFED AND CONFIGURED), RADAR VECTORS DSNDING TO 4000 FT, HEADING NE, IMC, WX AT GLA GOOD: 5 KM VISIBILITY, 2000 FT BROKEN, WIND 5 KTS, CAPT IS PF, FO IS PNF. INSTRUCTED TO TURN L TO 185 DEG HDG, RWY CHANGE TO RWY 5, VISIBILITY MIDFIELD 700 FT WITH LOW LEVEL FOG. DUE TO WX CHANGE, WE NOW BEGIN BRIEFING AND SETTING UP FOR A MONITORED APCH. BOTH OF US ARE HAVING TROUBLE UNDERSTANDING CTLR. WE KEEP ASKING HIM TO REPEAT. WE ARE VERY BUSY AT THIS POINT WITH BRIEFING, AND BOTH OF US HEAR CTLR ISSUE CLRNC TO DSND TO 3000 FT. FO READS BACK CLRNC, 3000 FT IS CONFIRMED SET IN ALT WINDOW BY BOTH PLTS, AND WE DSND TO 3000 FT. CTLR THEN SAID, 'CONFIRM LEVEL AT 4000 FT.' FO REPLIES, 'NEGATIVE, LEVEL AT 3000 FT AS ASSIGNED.' CTLR SAYS, 'OK, JUST STAY AT 3000 FT.' WE CONTACTED GLASGOW CTLRS BY PHONE ON THE GND, AND AFTER LISTENING TO TAPES, DETERMINED THAT CLRNC WAS FOR ANOTHER ACR AND BOTH OF US ANSWERED THE CLRNC AT EXACTLY THE SAME TIME. ON TAPE IT WAS GARBLED, BUT ENDED WITH AUDIBLE,'...X,' THE LAST NUMBER OF OUR CALL SIGN. CTLR DID NOT ASK FOR CLARIFICATION OF WHO ANSWERED CLRNC, AND WE DID NOT KNOW WE HAD ANSWERED SOMEONE ELSE'S CLRNC. ATC SUPVR ADMITTED LATE RWY CHANGE MAY HAVE ADDED TO CONFUSION. IT CERTAINLY INCREASED OUR WORKLOAD, WHICH WAS ALREADY INCREASED DUE TO THE FOG WX CHANGE, AND WAS QUESTIONABLE WITH SUCH LIGHT WINDS. RESPONSIBILITY LIES WITH BOTH US AND CTLR. WE MISTOOK AND ANSWERED SOMEONE ELSE'S CLRNC (DUE TO OUR HIGH WORKLOAD) AND CTLR FOR NOT CLARIFYING READBACK WHEN IT WAS OBVIOUSLY GARBLED AND ENDED WITH '...X,' NOT '...Y.'

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.