Narrative:

First officer obtained clearance, reading back the following: 'military M4000, r-hand squawk XXXX.' clearance delivery responded affirmatively after some discussion regarding the squawk. On departure, we contacted departure control reporting that we were climbing to 4000 ft. She responded with 'maintain runway heading.' about 2 mins later, the departure controller questioned if we were climbing. We responded that we were maintaining 4000 ft as assigned. She (ATC) questioned who assigned us 4000 ft. We stated that we were assigned 4000 ft from clearance delivery. Her (ATC) response was that she would 'check on that.' later the same day, I called the buf TRACON to inquire about the confusion on our departure. I was informed after some discussion and review of the tapes that the clearance was to climb to 10000 ft the first officer read back 4000 ft and the clearance delivery person did not detect the error. I read the clearance as written by the first officer and 4000 ft was written down. Prevention: 1) greater diligence by all parties concerned. 2) departure control confirm altitude climbing to. 3) if in doubt (any doubt, no matter how little), question and confirm!

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Original NASA ASRS Text

Title: A B737 FLC MISINTERPS THE CLRNC AND LEVELS OFF AT 4000 FT DURING A DEP PROC THAT HAD ISSUED A 10000 FT CLB OUT OF BUF, NY.

Narrative: FO OBTAINED CLRNC, READING BACK THE FOLLOWING: 'MIL M4000, R-HAND SQUAWK XXXX.' CLRNC DELIVERY RESPONDED AFFIRMATIVELY AFTER SOME DISCUSSION REGARDING THE SQUAWK. ON DEP, WE CONTACTED DEP CTL RPTING THAT WE WERE CLBING TO 4000 FT. SHE RESPONDED WITH 'MAINTAIN RWY HDG.' ABOUT 2 MINS LATER, THE DEP CTLR QUESTIONED IF WE WERE CLBING. WE RESPONDED THAT WE WERE MAINTAINING 4000 FT AS ASSIGNED. SHE (ATC) QUESTIONED WHO ASSIGNED US 4000 FT. WE STATED THAT WE WERE ASSIGNED 4000 FT FROM CLRNC DELIVERY. HER (ATC) RESPONSE WAS THAT SHE WOULD 'CHK ON THAT.' LATER THE SAME DAY, I CALLED THE BUF TRACON TO INQUIRE ABOUT THE CONFUSION ON OUR DEP. I WAS INFORMED AFTER SOME DISCUSSION AND REVIEW OF THE TAPES THAT THE CLRNC WAS TO CLB TO 10000 FT THE FO READ BACK 4000 FT AND THE CLRNC DELIVERY PERSON DID NOT DETECT THE ERROR. I READ THE CLRNC AS WRITTEN BY THE FO AND 4000 FT WAS WRITTEN DOWN. PREVENTION: 1) GREATER DILIGENCE BY ALL PARTIES CONCERNED. 2) DEP CTL CONFIRM ALT CLBING TO. 3) IF IN DOUBT (ANY DOUBT, NO MATTER HOW LITTLE), QUESTION AND CONFIRM!

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.