Narrative:

I was captain and PF from dtw to phl. We had just taken off from 21L at dtw, and were being vectored during out climb. Initially we were cleared to 10000'. We were on an east heading, and as we approached 9000' and I began to level off, departure gave us what I thought was a clearance to 11000'. Our procedures call for PNF to set in altitudes on the MCP, and for the PF to repeat the clearance altitude. I repeated the cleared altitude of 11000' and pressed EPR on the automatic throttle control panel to continue the climb--I was hand-flying the aircraft--and the aircraft increased its climb rate. The copilot said what I thought was 'cleared to 11000.' I did not look at the altitude window to see what he had set in. As we were passing through 9700' at a rapid pace, he said, 'level 10000,' and pointed to the altitude window. Sure enough, it still said 10000'. I pushed the nose over as rapidly as I could west/O disturbing the passenger and we ended up peaking out at 10350'. Departure control queried, 'confirm level at 10000.' my copilot rogered, 'we're leveling at 10000.' that was all that was said, and we were cleared to a higher altitude and on course shortly after. I asked my copilot what was really said, and he said that departure had pointed out traffic at 11000'. Also, that when I had said 'cleared to 11000,' he had replied that 'he's clear at 11000,' referring to the traffic. He then said, 'boy, I'll never say that again.' it was the end of a long day, but I misheard, confirmed by stating the altitude I thought we were cleared to, but didn't confirm by looking at the altitude window on the MCP. I'll never do that again, either.

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Original NASA ASRS Text

Title: ACR LGT ALT DEVIATION OVERSHOT DURING CLIMBOUT FROM DTW.

Narrative: I WAS CAPT AND PF FROM DTW TO PHL. WE HAD JUST TAKEN OFF FROM 21L AT DTW, AND WERE BEING VECTORED DURING OUT CLB. INITIALLY WE WERE CLRED TO 10000'. WE WERE ON AN E HDG, AND AS WE APCHED 9000' AND I BEGAN TO LEVEL OFF, DEP GAVE US WHAT I THOUGHT WAS A CLRNC TO 11000'. OUR PROCS CALL FOR PNF TO SET IN ALTS ON THE MCP, AND FOR THE PF TO REPEAT THE CLRNC ALT. I REPEATED THE CLRED ALT OF 11000' AND PRESSED EPR ON THE AUTO THROTTLE CTL PANEL TO CONTINUE THE CLB--I WAS HAND-FLYING THE ACFT--AND THE ACFT INCREASED ITS CLB RATE. THE COPLT SAID WHAT I THOUGHT WAS 'CLRED TO 11000.' I DID NOT LOOK AT THE ALT WINDOW TO SEE WHAT HE HAD SET IN. AS WE WERE PASSING THROUGH 9700' AT A RAPID PACE, HE SAID, 'LEVEL 10000,' AND POINTED TO THE ALT WINDOW. SURE ENOUGH, IT STILL SAID 10000'. I PUSHED THE NOSE OVER AS RAPIDLY AS I COULD W/O DISTURBING THE PAX AND WE ENDED UP PEAKING OUT AT 10350'. DEP CTL QUERIED, 'CONFIRM LEVEL AT 10000.' MY COPLT ROGERED, 'WE'RE LEVELING AT 10000.' THAT WAS ALL THAT WAS SAID, AND WE WERE CLRED TO A HIGHER ALT AND ON COURSE SHORTLY AFTER. I ASKED MY COPLT WHAT WAS REALLY SAID, AND HE SAID THAT DEP HAD POINTED OUT TFC AT 11000'. ALSO, THAT WHEN I HAD SAID 'CLRED TO 11000,' HE HAD REPLIED THAT 'HE'S CLR AT 11000,' REFERRING TO THE TFC. HE THEN SAID, 'BOY, I'LL NEVER SAY THAT AGAIN.' IT WAS THE END OF A LONG DAY, BUT I MISHEARD, CONFIRMED BY STATING THE ALT I THOUGHT WE WERE CLRED TO, BUT DIDN'T CONFIRM BY LOOKING AT THE ALT WINDOW ON THE MCP. I'LL NEVER DO THAT AGAIN, EITHER.

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.