Narrative:

Just past arlin at 11000 ft, 250 KTS, received clearance to 075 degree heading and (we thought) 7000 ft, and first officer read back 7000 ft, without comment from ATC. First officer went off frequency to talk to commanding officer, and I received a frequency change shortly thereafter. Upon checking in on new frequency, I was told I needed to climb to 9000 ft, that we were cleared to 10000 ft, not 7000 ft. (Altitude was approximately 8400 ft at that time.) promptly complied. No traffic conflict existed and no further comments received from ATC. I was pretty sure we both heard 7000 ft, because the first officer initially read back 070 degrees instead of 075 degrees on the heading, and I thought to myself that 'he got the 7's mixed up.' contributing factors: flying a non FMS aircraft (we don't fly it often at my base) which meant a little more distraction on my part adding up numbers for crossing restrs. Also, this was the first officer's very first month on line after finishing IOE. Supplemental information from acn 477116: while descending on arlin 2 to phx, just east of arlin we received instructions to turn left 075 degrees and descend to 7000 ft. I read back the clearance and the controller did not correct me. As the captain started the descent, I went off frequency to check in with company. At about 8400 ft, the captain started to climb and said the controller had told us we were only cleared to 10000 ft and wanted us back up to 9000 ft. We complied with the instructions. There were no traffic conflicts apparent and we continued to phx with no more mention of the situation from ATC.

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Original NASA ASRS Text

Title: B737. ALT CLRNC IN DISPUTE IN PHX CLASS B AIRSPACE.

Narrative: JUST PAST ARLIN AT 11000 FT, 250 KTS, RECEIVED CLRNC TO 075 DEG HDG AND (WE THOUGHT) 7000 FT, AND FO READ BACK 7000 FT, WITHOUT COMMENT FROM ATC. FO WENT OFF FREQ TO TALK TO COMMANDING OFFICER, AND I RECEIVED A FREQ CHANGE SHORTLY THEREAFTER. UPON CHKING IN ON NEW FREQ, I WAS TOLD I NEEDED TO CLB TO 9000 FT, THAT WE WERE CLRED TO 10000 FT, NOT 7000 FT. (ALT WAS APPROX 8400 FT AT THAT TIME.) PROMPTLY COMPLIED. NO TFC CONFLICT EXISTED AND NO FURTHER COMMENTS RECEIVED FROM ATC. I WAS PRETTY SURE WE BOTH HEARD 7000 FT, BECAUSE THE FO INITIALLY READ BACK 070 DEGS INSTEAD OF 075 DEGS ON THE HDG, AND I THOUGHT TO MYSELF THAT 'HE GOT THE 7'S MIXED UP.' CONTRIBUTING FACTORS: FLYING A NON FMS ACFT (WE DON'T FLY IT OFTEN AT MY BASE) WHICH MEANT A LITTLE MORE DISTR ON MY PART ADDING UP NUMBERS FOR XING RESTRS. ALSO, THIS WAS THE FO'S VERY FIRST MONTH ON LINE AFTER FINISHING IOE. SUPPLEMENTAL INFO FROM ACN 477116: WHILE DSNDING ON ARLIN 2 TO PHX, JUST E OF ARLIN WE RECEIVED INSTRUCTIONS TO TURN L 075 DEGS AND DSND TO 7000 FT. I READ BACK THE CLRNC AND THE CTLR DID NOT CORRECT ME. AS THE CAPT STARTED THE DSCNT, I WENT OFF FREQ TO CHK IN WITH COMPANY. AT ABOUT 8400 FT, THE CAPT STARTED TO CLB AND SAID THE CTLR HAD TOLD US WE WERE ONLY CLRED TO 10000 FT AND WANTED US BACK UP TO 9000 FT. WE COMPLIED WITH THE INSTRUCTIONS. THERE WERE NO TFC CONFLICTS APPARENT AND WE CONTINUED TO PHX WITH NO MORE MENTION OF THE SIT FROM 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.