Narrative:

First officer on the flight, I was flying the aircraft. Center cleared us to descended from FL390 to FL290 (no restrictions). While captain was making a passenger announcement, I leveled off at FL290. Shortly after, a transmission by center was totally blocked by other aircraft. None of it was legible. Thinking that it might be for us, I stated over the radio: 'you were blocked.' (silence.) other aircraft on the frequency: 'you were stepped on.' (dead silence.) 2-3 mins later center called us asking what altitude we were descending through. Captain answered: 'we are level at FL290.' center: 'descended to FL240, expedite through 270.' nothing else was said, we complied. After entering operations at detroit airport, agent advised ATC was on the phone and wanted to talk to captain about possible traffic conflict over dryer VOR, and wanted our version of the facts. ATC called us later that night and said that after listening to the tapes, they would not pursue the matter any further. Conclusion: ATC was blocked by other aircraft transmitting at the same time, was advised twice of the fact, but never repeated the clearance. Thinking that it might be for us, I should have insisted that ATC repeat last transmission or state: 'disregard.' the fact that 2 aircraft advised of transmission blockage was not enough. Supplemental information from acn 82165: apparently the controller issued a clearance for us to cross dryer at FL240. Never having received the clearance, and never having read back any clearance, we remained at FL290. The blocked transmission may have been directed at us, but the controller never repeated himself even after 2 aircraft reported the transmission blocked. Also, after being told to expedite through FL270, we were never told of any traffic conflict while in the air.

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Original NASA ASRS Text

Title: LGT MISSED A DESCENT CLRNC AND CTLR LATER HAD TO HAVE ACFT EXPEDITE DESCENT FOR SEPARATION.

Narrative: F/O ON THE FLT, I WAS FLYING THE ACFT. CENTER CLRED US TO DESCENDED FROM FL390 TO FL290 (NO RESTRICTIONS). WHILE CAPT WAS MAKING A PAX ANNOUNCEMENT, I LEVELED OFF AT FL290. SHORTLY AFTER, A XMISSION BY CENTER WAS TOTALLY BLOCKED BY OTHER ACFT. NONE OF IT WAS LEGIBLE. THINKING THAT IT MIGHT BE FOR US, I STATED OVER THE RADIO: 'YOU WERE BLOCKED.' (SILENCE.) OTHER ACFT ON THE FREQ: 'YOU WERE STEPPED ON.' (DEAD SILENCE.) 2-3 MINS LATER CENTER CALLED US ASKING WHAT ALT WE WERE DSNDING THROUGH. CAPT ANSWERED: 'WE ARE LEVEL AT FL290.' CENTER: 'DESCENDED TO FL240, EXPEDITE THROUGH 270.' NOTHING ELSE WAS SAID, WE COMPLIED. AFTER ENTERING OPS AT DETROIT ARPT, AGENT ADVISED ATC WAS ON THE PHONE AND WANTED TO TALK TO CAPT ABOUT POSSIBLE TFC CONFLICT OVER DRYER VOR, AND WANTED OUR VERSION OF THE FACTS. ATC CALLED US LATER THAT NIGHT AND SAID THAT AFTER LISTENING TO THE TAPES, THEY WOULD NOT PURSUE THE MATTER ANY FURTHER. CONCLUSION: ATC WAS BLOCKED BY OTHER ACFT XMITTING AT THE SAME TIME, WAS ADVISED TWICE OF THE FACT, BUT NEVER REPEATED THE CLRNC. THINKING THAT IT MIGHT BE FOR US, I SHOULD HAVE INSISTED THAT ATC REPEAT LAST XMISSION OR STATE: 'DISREGARD.' THE FACT THAT 2 ACFT ADVISED OF XMISSION BLOCKAGE WAS NOT ENOUGH. SUPPLEMENTAL INFO FROM ACN 82165: APPARENTLY THE CTLR ISSUED A CLRNC FOR US TO CROSS DRYER AT FL240. NEVER HAVING RECEIVED THE CLRNC, AND NEVER HAVING READ BACK ANY CLRNC, WE REMAINED AT FL290. THE BLOCKED XMISSION MAY HAVE BEEN DIRECTED AT US, BUT THE CTLR NEVER REPEATED HIMSELF EVEN AFTER 2 ACFT RPTED THE XMISSION BLOCKED. ALSO, AFTER BEING TOLD TO EXPEDITE THROUGH FL270, WE WERE NEVER TOLD OF ANY TFC CONFLICT WHILE IN THE AIR.

Data retrieved from NASA's ASRS site as of August 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.