Narrative:

Near hlc at FL390 we encountered light turbulence. I requested FL350 and was told to wait 6 mins or take a substantial turn. I said we would take the turn. ATC responded by saying stand by. We were then given a left turn 30 degrees and a descent while I was making a PA. I heard the first officer read back FL350. Descending out of approximately FL366 we got a TCASII alert reduce descent followed by monitor vertical speed. We leveled off about FL361. ATC asked 'you are descending to FL370 aren't you?' not the kind of question you would like to hear. We answered that we were responding to a TCASII alert while descending to FL350. ATC then told us to climb to FL370. Supplemental information from acn 416309: the first officer leveled off at FL360 and the traffic passed underneath us. I was unaware that when the captain went to make his PA he turned his overhead speaker off. The first officer's speaker was off because he used his ear piece. I never heard the actual clearance from center until the captain came back on frequency. Lesson: stereo means both speakers on in order to keep the flight engineer in the loop.

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Original NASA ASRS Text

Title: A DC10 REQUESTS DSCNT TO FL350. ARTCC CLRS FLC TO FL370, BUT FLC FLIES THROUGH FL370 DOWN TO FL360.

Narrative: NEAR HLC AT FL390 WE ENCOUNTERED LIGHT TURB. I REQUESTED FL350 AND WAS TOLD TO WAIT 6 MINS OR TAKE A SUBSTANTIAL TURN. I SAID WE WOULD TAKE THE TURN. ATC RESPONDED BY SAYING STAND BY. WE WERE THEN GIVEN A L TURN 30 DEGS AND A DSCNT WHILE I WAS MAKING A PA. I HEARD THE FO READ BACK FL350. DSNDING OUT OF APPROX FL366 WE GOT A TCASII ALERT REDUCE DSCNT FOLLOWED BY MONITOR VERT SPD. WE LEVELED OFF ABOUT FL361. ATC ASKED 'YOU ARE DSNDING TO FL370 AREN'T YOU?' NOT THE KIND OF QUESTION YOU WOULD LIKE TO HEAR. WE ANSWERED THAT WE WERE RESPONDING TO A TCASII ALERT WHILE DSNDING TO FL350. ATC THEN TOLD US TO CLB TO FL370. SUPPLEMENTAL INFO FROM ACN 416309: THE FO LEVELED OFF AT FL360 AND THE TFC PASSED UNDERNEATH US. I WAS UNAWARE THAT WHEN THE CAPT WENT TO MAKE HIS PA HE TURNED HIS OVERHEAD SPEAKER OFF. THE FO'S SPEAKER WAS OFF BECAUSE HE USED HIS EAR PIECE. I NEVER HEARD THE ACTUAL CLRNC FROM CTR UNTIL THE CAPT CAME BACK ON FREQ. LESSON: STEREO MEANS BOTH SPEAKERS ON IN ORDER TO KEEP THE FE IN THE LOOP.

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.