Narrative:

ZME pointed out an large transport at 10 O'clock and FL270. He issued a clearance for us to descend from FL260. I don't specifically recall the clearance limit altitude issued, but I do clearly recall the first officer reading back FL230, which was acknowledged by center. During our descent center cleared the large transport to FL240. After we were level at FL230, center asked our altitude, and he responded that we should be at FL240 (where the large transport was cleared). We replied that we had understood and read back FL230. He said, 'no problem,' and acknowledged that he did not recall our readback. Obviously, the communication link is broken if a readback is acknowledged west/O comprehension. There could have been other traffic at FL230!

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Original NASA ASRS Text

Title: FLT CREW OF MLG RECEIVED AND READ BACK CLRNC TO FL230. CENTER CTLR QUESTIONED THE ALT AFTER FLT LEVELED.

Narrative: ZME POINTED OUT AN LGT AT 10 O'CLOCK AND FL270. HE ISSUED A CLRNC FOR US TO DSND FROM FL260. I DON'T SPECIFICALLY RECALL THE CLRNC LIMIT ALT ISSUED, BUT I DO CLEARLY RECALL THE F/O READING BACK FL230, WHICH WAS ACKNOWLEDGED BY CENTER. DURING OUR DSNT CENTER CLRED THE LGT TO FL240. AFTER WE WERE LEVEL AT FL230, CENTER ASKED OUR ALT, AND HE RESPONDED THAT WE SHOULD BE AT FL240 (WHERE THE LGT WAS CLRED). WE REPLIED THAT WE HAD UNDERSTOOD AND READ BACK FL230. HE SAID, 'NO PROB,' AND ACKNOWLEDGED THAT HE DID NOT RECALL OUR READBACK. OBVIOUSLY, THE COM LINK IS BROKEN IF A READBACK IS ACKNOWLEDGED W/O COMPREHENSION. THERE COULD HAVE BEEN OTHER TFC AT FL230!

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.