Narrative:

Problem concerned hear-back of altitude clearance. After departure from phx area and climbing to 14000', we were switched to ZAB. We were given further climb to what my copilot and I heard to be FL270. I repeated back FL270 to center. Aircraft was being flown on autoplt by my copilot and, in accordance with company procedures, he (PF) selected 27000' in altitude selector and confirmed the altitude with me. Next call from center was to alert us to traffic at 12 O'clock. Since the flight conditions were very clear visibility, I shortly spotted traffic ahead of us. As the traffic passed a couple of miles to our side, I remarked to the copilot that it was strange that we would be passing that close to us when we were passing his altitude. We were between 20500 and 21000', climbing at 1200-1500 FPM, when the traffic passed. Center called and informed us that we were cleared only to FL200. I responded that we had been cleared to FL270 and repeated back FL270. After a few moments of silence, center told us to stop our climb at FL240. I acknowledged FL240 and copilot reset altitude selector. As we were passing FL220, center again called and told us to maintain FL230. I again acknowledged and the new altitude was reset. We leveled at FL230. The power was reset for cruise and we began discussing what had just happened when center again called (in what appeared to be a nervous voice) and told us to level at FL230. I informed him that we were already level at FL230. Since we were both sure that the altitude had been given and repeated back as FL270, this action served to confirm our suspicion that we were correct. Remainder of flight was uneventful. Subsequent conversation with ZAB supervisor indicated that a violation report would be automatic because of the parameters involved (2 mi and 400').

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Original NASA ASRS Text

Title: FLT CREW OF MLG UNDERSTOOD CLEARED TO FL270. CLIMBING THROUGH 20500' FLT CREW SAW TRAFFIC 2 MILES, 400' ABOVE. CENTER CTLR ALLEGED FLT CREW CLEARED ONLY TO FL200. CONFLICT ALERT. VIOLATION FILED.

Narrative: PROB CONCERNED HEAR-BACK OF ALT CLRNC. AFTER DEP FROM PHX AREA AND CLBING TO 14000', WE WERE SWITCHED TO ZAB. WE WERE GIVEN FURTHER CLB TO WHAT MY COPLT AND I HEARD TO BE FL270. I REPEATED BACK FL270 TO CENTER. ACFT WAS BEING FLOWN ON AUTOPLT BY MY COPLT AND, IN ACCORDANCE WITH COMPANY PROCS, HE (PF) SELECTED 27000' IN ALT SELECTOR AND CONFIRMED THE ALT WITH ME. NEXT CALL FROM CENTER WAS TO ALERT US TO TFC AT 12 O'CLOCK. SINCE THE FLT CONDITIONS WERE VERY CLR VISIBILITY, I SHORTLY SPOTTED TFC AHEAD OF US. AS THE TFC PASSED A COUPLE OF MILES TO OUR SIDE, I REMARKED TO THE COPLT THAT IT WAS STRANGE THAT WE WOULD BE PASSING THAT CLOSE TO US WHEN WE WERE PASSING HIS ALT. WE WERE BTWN 20500 AND 21000', CLBING AT 1200-1500 FPM, WHEN THE TFC PASSED. CENTER CALLED AND INFORMED US THAT WE WERE CLRED ONLY TO FL200. I RESPONDED THAT WE HAD BEEN CLRED TO FL270 AND REPEATED BACK FL270. AFTER A FEW MOMENTS OF SILENCE, CENTER TOLD US TO STOP OUR CLB AT FL240. I ACKNOWLEDGED FL240 AND COPLT RESET ALT SELECTOR. AS WE WERE PASSING FL220, CENTER AGAIN CALLED AND TOLD US TO MAINTAIN FL230. I AGAIN ACKNOWLEDGED AND THE NEW ALT WAS RESET. WE LEVELED AT FL230. THE PWR WAS RESET FOR CRUISE AND WE BEGAN DISCUSSING WHAT HAD JUST HAPPENED WHEN CENTER AGAIN CALLED (IN WHAT APPEARED TO BE A NERVOUS VOICE) AND TOLD US TO LEVEL AT FL230. I INFORMED HIM THAT WE WERE ALREADY LEVEL AT FL230. SINCE WE WERE BOTH SURE THAT THE ALT HAD BEEN GIVEN AND REPEATED BACK AS FL270, THIS ACTION SERVED TO CONFIRM OUR SUSPICION THAT WE WERE CORRECT. REMAINDER OF FLT WAS UNEVENTFUL. SUBSEQUENT CONVERSATION WITH ZAB SUPVR INDICATED THAT A VIOLATION RPT WOULD BE AUTOMATIC BECAUSE OF THE PARAMETERS INVOLVED (2 MI AND 400').

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.