Narrative:

We had been cleared to cross dresr intersection at FL240. This clearance was complied with. Shortly after this, the controller on 134.67 gave us a clearance to descend to 12000 ft and contact controller on 124.22. The altitude selector was set to 12000 ft via company protocol and the descent was initiated. The captain, who was working the radios, made a 'check in' on the new frequency, did not receive an immediate reply. The crew was then distraction by conversation. Shortly thereafter the controller called us and asked why we were descending and why we had not answered her radio calls. At that time the controller told us that we had been considered a NORDO aircraft, and that we should stop our descent at 15000 ft. This clearance was complied with. It was obvious that the controller was not aware of our clearance to descend to 12000 ft. In retrospect it is possible that we heard a clearance for another aircraft with similar sounding call sign, thought it was ours, made a readback and switched the radio before the controller had time to correct the mistake. The solution to this problem is to read back clearance and give a slight delay before switching the frequency. The other solution to the problem that we had is on the check-in call, make sure controller answers. If not answered on first try, delay for a short time and make second call in case controller was busy on a ground line. If no answer on second try, go back to previous frequency, where last controller would undoubtedly correct any mistake in progress.

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Original NASA ASRS Text

Title: MDT ACFT IN CRUISE FLC THOUGHT THEY RECEIVED DSCNT CLRNC AND FREQ CHANGE. RPTR FO, PF, BELIEVES THEY TOOK CLRNC FOR ANOTHER ACFT AND CHANGED FREQ BEFORE THE CTLR COULD CORRECT THE CALL SIGN ERROR. NEXT CTLR QUESTIONED THEIR ALT AND ISSUED NEW ALT CLRNC.

Narrative: WE HAD BEEN CLRED TO CROSS DRESR INTXN AT FL240. THIS CLRNC WAS COMPLIED WITH. SHORTLY AFTER THIS, THE CTLR ON 134.67 GAVE US A CLRNC TO DSND TO 12000 FT AND CONTACT CTLR ON 124.22. THE ALT SELECTOR WAS SET TO 12000 FT VIA COMPANY PROTOCOL AND THE DSCNT WAS INITIATED. THE CAPT, WHO WAS WORKING THE RADIOS, MADE A 'CHK IN' ON THE NEW FREQ, DID NOT RECEIVE AN IMMEDIATE REPLY. THE CREW WAS THEN DISTR BY CONVERSATION. SHORTLY THEREAFTER THE CTLR CALLED US AND ASKED WHY WE WERE DSNDING AND WHY WE HAD NOT ANSWERED HER RADIO CALLS. AT THAT TIME THE CTLR TOLD US THAT WE HAD BEEN CONSIDERED A NORDO ACFT, AND THAT WE SHOULD STOP OUR DSCNT AT 15000 FT. THIS CLRNC WAS COMPLIED WITH. IT WAS OBVIOUS THAT THE CTLR WAS NOT AWARE OF OUR CLRNC TO DSND TO 12000 FT. IN RETROSPECT IT IS POSSIBLE THAT WE HEARD A CLRNC FOR ANOTHER ACFT WITH SIMILAR SOUNDING CALL SIGN, THOUGHT IT WAS OURS, MADE A READBACK AND SWITCHED THE RADIO BEFORE THE CTLR HAD TIME TO CORRECT THE MISTAKE. THE SOLUTION TO THIS PROB IS TO READ BACK CLRNC AND GIVE A SLIGHT DELAY BEFORE SWITCHING THE FREQ. THE OTHER SOLUTION TO THE PROB THAT WE HAD IS ON THE CHK-IN CALL, MAKE SURE CTLR ANSWERS. IF NOT ANSWERED ON FIRST TRY, DELAY FOR A SHORT TIME AND MAKE SECOND CALL IN CASE CTLR WAS BUSY ON A GND LINE. IF NO ANSWER ON SECOND TRY, GO BACK TO PREVIOUS FREQ, WHERE LAST CTLR WOULD UNDOUBTEDLY CORRECT ANY MISTAKE IN PROGRESS.

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.