Narrative:

En route to dtw-dca, ZOB called, gave instructions to 'descend to FL350, be out of FL370 in 2 mins.' (note: we were at FL410.) first officer was on #2 radio with destination station. I acknowledged the descent clearance but mistook the controller's clearance as instructions to begin our descent within 2 mins. As we descended through FL395, I asked the first officer to get clarification from ZOB as to our clearance. When queried, the controller advised we had 20 seconds to be out of FL370, that it didn't look like we'd make that. He then advised/directed a left turn, from our 105 degree heading, to 050 degrees, then 010 degrees. While in our turn, the TCASII warning announced 'traffic, traffic' followed by an RA of 'climb, climb.' we were in a 2000-3000 FPM descent at the time. I immediately disconnected the autoplt and tightened the turn to the left while pulling up into a climb. The TCASII displayed our conflicting traffic 300 ft below and to the right. The first officer advised he was passing off to our right about 3 mi away, and then advised ATC that we were climbing due to a TCASII RA. ATC acknowledged, 'roger, advise when you have descended through FL370....' human factors: a long crew duty day coupled with a very short rest period prior to this day made for a tired cockpit crew. The controller continuously transposed our call sign from XX324 to XX234. The initial clearance required what I regard as an excessive descent rate (2000 plus FPM) from high altitude (FL410). Controllers don't seem to appreciate that such high descent rates are difficult and uncomfortable for the passenger. In retrospect, I question the need for such a clearance given its difficulty and the need for immediate pilot action. Supplemental information from acn 281650: the descent was a 2000- 3000 FPM rate and the controller issued a right turn to 050 degrees (aircraft was on heading of about 100 degrees). Controller was asked to verify right turn, at which time he said left turn, heading 010 degrees. Controller's use of proper call sign for aircraft was not clear and I believe he was mixing up the numbers on at least 1 of his calls. Aircraft was in the left turn and descending when TCASII gave 'traffic, traffic' followed by 'climb, climb.' display showed aircraft at 1-2 O'clock converging, 300 ft below. PF disconnected autoplt and began climb to follow TCASII RA, still in left turn. Controller was advised by PNF that aircraft was in turn and climbing to 'follow TCASII RA.' controller acknowledged and asked for advisory when we resumed descent through FL370. Visual contact was established with intruder aircraft, 2-3 O'clock, 300 ft below, approximately 3 mi horizontal. (That aircraft then asked center about traffic at his 2 O'clock.) we leveled FL350 and received clearance back on course. Remainder of segment was uneventful.

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Original NASA ASRS Text

Title: PLTDEV RESULTING IN A LOSS OF SEPARATION BTWN ACR X AND ACFT Y.

Narrative: ENRTE TO DTW-DCA, ZOB CALLED, GAVE INSTRUCTIONS TO 'DSND TO FL350, BE OUT OF FL370 IN 2 MINS.' (NOTE: WE WERE AT FL410.) FO WAS ON #2 RADIO WITH DEST STATION. I ACKNOWLEDGED THE DSCNT CLRNC BUT MISTOOK THE CTLR'S CLRNC AS INSTRUCTIONS TO BEGIN OUR DSCNT WITHIN 2 MINS. AS WE DSNDED THROUGH FL395, I ASKED THE FO TO GET CLARIFICATION FROM ZOB AS TO OUR CLRNC. WHEN QUERIED, THE CTLR ADVISED WE HAD 20 SECONDS TO BE OUT OF FL370, THAT IT DIDN'T LOOK LIKE WE'D MAKE THAT. HE THEN ADVISED/DIRECTED A L TURN, FROM OUR 105 DEG HDG, TO 050 DEGS, THEN 010 DEGS. WHILE IN OUR TURN, THE TCASII WARNING ANNOUNCED 'TFC, TFC' FOLLOWED BY AN RA OF 'CLB, CLB.' WE WERE IN A 2000-3000 FPM DSCNT AT THE TIME. I IMMEDIATELY DISCONNECTED THE AUTOPLT AND TIGHTENED THE TURN TO THE L WHILE PULLING UP INTO A CLB. THE TCASII DISPLAYED OUR CONFLICTING TFC 300 FT BELOW AND TO THE R. THE FO ADVISED HE WAS PASSING OFF TO OUR R ABOUT 3 MI AWAY, AND THEN ADVISED ATC THAT WE WERE CLBING DUE TO A TCASII RA. ATC ACKNOWLEDGED, 'ROGER, ADVISE WHEN YOU HAVE DSNDED THROUGH FL370....' HUMAN FACTORS: A LONG CREW DUTY DAY COUPLED WITH A VERY SHORT REST PERIOD PRIOR TO THIS DAY MADE FOR A TIRED COCKPIT CREW. THE CTLR CONTINUOUSLY TRANSPOSED OUR CALL SIGN FROM XX324 TO XX234. THE INITIAL CLRNC REQUIRED WHAT I REGARD AS AN EXCESSIVE DSCNT RATE (2000 PLUS FPM) FROM HIGH ALT (FL410). CTLRS DON'T SEEM TO APPRECIATE THAT SUCH HIGH DSCNT RATES ARE DIFFICULT AND UNCOMFORTABLE FOR THE PAX. IN RETROSPECT, I QUESTION THE NEED FOR SUCH A CLRNC GIVEN ITS DIFFICULTY AND THE NEED FOR IMMEDIATE PLT ACTION. SUPPLEMENTAL INFO FROM ACN 281650: THE DSCNT WAS A 2000- 3000 FPM RATE AND THE CTLR ISSUED A R TURN TO 050 DEGS (ACFT WAS ON HDG OF ABOUT 100 DEGS). CTLR WAS ASKED TO VERIFY R TURN, AT WHICH TIME HE SAID L TURN, HDG 010 DEGS. CTLR'S USE OF PROPER CALL SIGN FOR ACFT WAS NOT CLR AND I BELIEVE HE WAS MIXING UP THE NUMBERS ON AT LEAST 1 OF HIS CALLS. ACFT WAS IN THE L TURN AND DSNDING WHEN TCASII GAVE 'TFC, TFC' FOLLOWED BY 'CLB, CLB.' DISPLAY SHOWED ACFT AT 1-2 O'CLOCK CONVERGING, 300 FT BELOW. PF DISCONNECTED AUTOPLT AND BEGAN CLB TO FOLLOW TCASII RA, STILL IN L TURN. CTLR WAS ADVISED BY PNF THAT ACFT WAS IN TURN AND CLBING TO 'FOLLOW TCASII RA.' CTLR ACKNOWLEDGED AND ASKED FOR ADVISORY WHEN WE RESUMED DSCNT THROUGH FL370. VISUAL CONTACT WAS ESTABLISHED WITH INTRUDER ACFT, 2-3 O'CLOCK, 300 FT BELOW, APPROX 3 MI HORIZ. (THAT ACFT THEN ASKED CTR ABOUT TFC AT HIS 2 O'CLOCK.) WE LEVELED FL350 AND RECEIVED CLRNC BACK ON COURSE. REMAINDER OF SEGMENT WAS UNEVENTFUL.

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.