Narrative:

After takeoff from runway 14L (iah), departure told us to turn right to 250 degrees followed by further right turn to 260 degrees and climb to 5000 ft. Out of 4000 ft the captain called 2 to go. He had dialed 6000 ft into the awl. Coming up to 5000 ft I heard departure call traffic at 2 O'clock and 8 mi, opposite direction at 6000 ft. I saw the traffic appear on the TCASII with plus 800 denoted. I immediately initiated stop climb and asked the captain to verify 6000 ft, because I remembered being cleared to 5000 ft. I retarded the throttles to idle and returned to 5000 ft. The aircraft peaked altitude at 5400 ft. At the same time all this was happening, houston departure was telling us to descend to 5000 ft immediately. At the same time we were getting a TA from our TCASII. Upon returning to 5000 ft, the flight progressed uneventfully. Supplemental information from acn 277378: on departure from iah we were cleared to 4000 ft. Subsequently received further clearance to 6000 ft and set altitude in altitude alerter. I believe I read back 6000 ft. We were advised of higher traffic but due to distrs don't recall his altitude. First officer was flying and noticed a separation on that traffic of less than 1000 ft on TCASII. He immediately returned from 5400-5000 ft. ATC then told us to level at 5000 ft by which time we were already level. After discussion between the crew, we really couldn't determine if we were really cleared to 5000 or 6000 ft. I did however read back 6000 ft and set it in the window. Guess I wasn't in the loop as well as I should have been.

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Original NASA ASRS Text

Title: ACFT CLBS 400 FT ABOVE CLRED ALT BECAUSE CLRNC IS MISUNDERSTOOD.

Narrative: AFTER TKOF FROM RWY 14L (IAH), DEP TOLD US TO TURN R TO 250 DEGS FOLLOWED BY FURTHER R TURN TO 260 DEGS AND CLB TO 5000 FT. OUT OF 4000 FT THE CAPT CALLED 2 TO GO. HE HAD DIALED 6000 FT INTO THE AWL. COMING UP TO 5000 FT I HEARD DEP CALL TFC AT 2 O'CLOCK AND 8 MI, OPPOSITE DIRECTION AT 6000 FT. I SAW THE TFC APPEAR ON THE TCASII WITH PLUS 800 DENOTED. I IMMEDIATELY INITIATED STOP CLB AND ASKED THE CAPT TO VERIFY 6000 FT, BECAUSE I REMEMBERED BEING CLRED TO 5000 FT. I RETARDED THE THROTTLES TO IDLE AND RETURNED TO 5000 FT. THE ACFT PEAKED ALT AT 5400 FT. AT THE SAME TIME ALL THIS WAS HAPPENING, HOUSTON DEP WAS TELLING US TO DSND TO 5000 FT IMMEDIATELY. AT THE SAME TIME WE WERE GETTING A TA FROM OUR TCASII. UPON RETURNING TO 5000 FT, THE FLT PROGRESSED UNEVENTFULLY. SUPPLEMENTAL INFO FROM ACN 277378: ON DEP FROM IAH WE WERE CLRED TO 4000 FT. SUBSEQUENTLY RECEIVED FURTHER CLRNC TO 6000 FT AND SET ALT IN ALT ALERTER. I BELIEVE I READ BACK 6000 FT. WE WERE ADVISED OF HIGHER TFC BUT DUE TO DISTRS DON'T RECALL HIS ALT. FO WAS FLYING AND NOTICED A SEPARATION ON THAT TFC OF LESS THAN 1000 FT ON TCASII. HE IMMEDIATELY RETURNED FROM 5400-5000 FT. ATC THEN TOLD US TO LEVEL AT 5000 FT BY WHICH TIME WE WERE ALREADY LEVEL. AFTER DISCUSSION BTWN THE CREW, WE REALLY COULDN'T DETERMINE IF WE WERE REALLY CLRED TO 5000 OR 6000 FT. I DID HOWEVER READ BACK 6000 FT AND SET IT IN THE WINDOW. GUESS I WASN'T IN THE LOOP AS WELL AS I SHOULD HAVE BEEN.

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.