Narrative:

Our flight departed rno en route to dfw at xx. On climb out while climbing through about FL190, with a clearance to FL230, we were switched to another controller at ZOA. This new controller cleared us to FL370, our filed altitude, and it came at the normal time in the flight profile. The controller also cleared us direct mina VOR. Over the mina VOR, while passing FL278, the controller asked our altitude and we responded, 'FL278 for FL370.' at this time we were informed our altitude clearance was FL270. I then quickly descended to FL270. I was the PF the aircraft and I set the altitude alert at FL370 while the copilot who was operating the radios read back FL370. All 3 crew members heard FL370 and there was no question or even any discussion of a question that we may have been cleared to only FL270. I am at a loss to suggest how to prevent a recurrence of this incident. How 2 people performing 2 separate acts, me setting the altitude alert and the copilot reading back FL370, came up with the same result which was wrong is baffling. Especially in this case, since at the time the clearance was given there was absolutely no distracting factor in the cockpit. I also brief and encourage my fellow crew members to speak up if they see, hear or think they hear anything that is not correct or a standard procedure. Possibly the only suggestion of prevention could be a controller's readback of a pilot's readback for altitudes, or a stronger differentiation in the way the words '2' and '3' are pronounced. Supplemental information from acn 142351: ZOA has said the tapes show we were given clearance to FL270 and I acknowledged climbing to FL270.

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Original NASA ASRS Text

Title: LGT FLT CREW RECEIVES, READS BACK CLRNC TO FL370. PASSING FL278, CTLR SAYS CLRNC WAS TO FL270.

Narrative: OUR FLT DEPARTED RNO ENRTE TO DFW AT XX. ON CLBOUT WHILE CLBING THROUGH ABOUT FL190, WITH A CLRNC TO FL230, WE WERE SWITCHED TO ANOTHER CTLR AT ZOA. THIS NEW CTLR CLRED US TO FL370, OUR FILED ALT, AND IT CAME AT THE NORMAL TIME IN THE FLT PROFILE. THE CTLR ALSO CLRED US DIRECT MINA VOR. OVER THE MINA VOR, WHILE PASSING FL278, THE CTLR ASKED OUR ALT AND WE RESPONDED, 'FL278 FOR FL370.' AT THIS TIME WE WERE INFORMED OUR ALT CLRNC WAS FL270. I THEN QUICKLY DSNDED TO FL270. I WAS THE PF THE ACFT AND I SET THE ALT ALERT AT FL370 WHILE THE COPLT WHO WAS OPERATING THE RADIOS READ BACK FL370. ALL 3 CREW MEMBERS HEARD FL370 AND THERE WAS NO QUESTION OR EVEN ANY DISCUSSION OF A QUESTION THAT WE MAY HAVE BEEN CLRED TO ONLY FL270. I AM AT A LOSS TO SUGGEST HOW TO PREVENT A RECURRENCE OF THIS INCIDENT. HOW 2 PEOPLE PERFORMING 2 SEPARATE ACTS, ME SETTING THE ALT ALERT AND THE COPLT READING BACK FL370, CAME UP WITH THE SAME RESULT WHICH WAS WRONG IS BAFFLING. ESPECIALLY IN THIS CASE, SINCE AT THE TIME THE CLRNC WAS GIVEN THERE WAS ABSOLUTELY NO DISTRACTING FACTOR IN THE COCKPIT. I ALSO BRIEF AND ENCOURAGE MY FELLOW CREW MEMBERS TO SPEAK UP IF THEY SEE, HEAR OR THINK THEY HEAR ANYTHING THAT IS NOT CORRECT OR A STANDARD PROC. POSSIBLY THE ONLY SUGGESTION OF PREVENTION COULD BE A CTLR'S READBACK OF A PLT'S READBACK FOR ALTS, OR A STRONGER DIFFERENTIATION IN THE WAY THE WORDS '2' AND '3' ARE PRONOUNCED. SUPPLEMENTAL INFO FROM ACN 142351: ZOA HAS SAID THE TAPES SHOW WE WERE GIVEN CLRNC TO FL270 AND I ACKNOWLEDGED CLBING TO FL270.

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.