Narrative:

When departing den on aug/thu/95, flying air carrier X den-tpa, we understood and acknowledged a position and hold clearance on runway 35L. While in position on runway 35L, tower told us we hadn't been cleared into position, we said we had, he said it was air carrier Y, departing runway 8, who had been cleared. After our arrival at tampa we contacted the tower supervisor at den upon our initiative and learned that they had already listened to the tapes and that the position and hold acknowledgements from both air carrier X and air carrier Y could be heard, transmitting over each other, with air carrier Y being the stronger xmissions and the one the controller heard, which explains our error not being caught and corrected by the controller. Whatever human factors contributed to this incident were aggravated by the system allowing us to hear all of the tower's xmissions on more than one frequency, but the acknowledgements on only the frequency to which we were assigned, and two similarly close flight numbered trips departing at the same time. Over the next several hours, as we flew air carrier X den-tpa and air carrier Y flew den- mia, as we were handed off from sector to sector and center to center a min or so ahead of them. We had reinforced in our minds the reality of needless, ever present confusion associated with similar numbered trips operating at the same time over the same route, which we feel contributed to this incident almost as much as the multiple frequency xmissions by ATC.

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Original NASA ASRS Text

Title: PLTDEV. ACR X TOOK CLRNC ISSUED TO ACR Y.

Narrative: WHEN DEPARTING DEN ON AUG/THU/95, FLYING ACR X DEN-TPA, WE UNDERSTOOD AND ACKNOWLEDGED A POS AND HOLD CLRNC ON RWY 35L. WHILE IN POS ON RWY 35L, TWR TOLD US WE HADN'T BEEN CLRED INTO POS, WE SAID WE HAD, HE SAID IT WAS ACR Y, DEPARTING RWY 8, WHO HAD BEEN CLRED. AFTER OUR ARR AT TAMPA WE CONTACTED THE TWR SUPVR AT DEN UPON OUR INITIATIVE AND LEARNED THAT THEY HAD ALREADY LISTENED TO THE TAPES AND THAT THE POS AND HOLD ACKNOWLEDGEMENTS FROM BOTH ACR X AND ACR Y COULD BE HEARD, XMITTING OVER EACH OTHER, WITH ACR Y BEING THE STRONGER XMISSIONS AND THE ONE THE CTLR HEARD, WHICH EXPLAINS OUR ERROR NOT BEING CAUGHT AND CORRECTED BY THE CTLR. WHATEVER HUMAN FACTORS CONTRIBUTED TO THIS INCIDENT WERE AGGRAVATED BY THE SYS ALLOWING US TO HEAR ALL OF THE TWR'S XMISSIONS ON MORE THAN ONE FREQ, BUT THE ACKNOWLEDGEMENTS ON ONLY THE FREQ TO WHICH WE WERE ASSIGNED, AND TWO SIMILARLY CLOSE FLT NUMBERED TRIPS DEPARTING AT THE SAME TIME. OVER THE NEXT SEVERAL HRS, AS WE FLEW ACR X DEN-TPA AND ACR Y FLEW DEN- MIA, AS WE WERE HANDED OFF FROM SECTOR TO SECTOR AND CTR TO CTR A MIN OR SO AHEAD OF THEM. WE HAD REINFORCED IN OUR MINDS THE REALITY OF NEEDLESS, EVER PRESENT CONFUSION ASSOCIATED WITH SIMILAR NUMBERED TRIPS OPERATING AT THE SAME TIME OVER THE SAME RTE, WHICH WE FEEL CONTRIBUTED TO THIS INCIDENT ALMOST AS MUCH AS THE MULTIPLE FREQ XMISSIONS BY ATC.

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.