Narrative:

ATC gave us a left turn to 360 degree (approximately 65 degree left turn) and descend to FL290. (Descent was given first, followed by the turn). We were descending at approximately 1100 FPM and turning to 360 degree when TCASII activated and showed a red arc everywhere except 1500-1800 down. I took aircraft from first officer and steepened to about 1800 FPM (somewhere in green arc). We spotted a widebody transport passing directly overhead about 500 ft higher. We completed turn and leveled at FL290. TCASII gave us a clear of traffic as widebody transport passed overhead. ATC then assigned a right turn to 090 degree and reintercepted J-42, as filed. I was surprised to get a RA from the TCASII (first officer and I both commented on the sudden left turn and descent). I perhaps waited 1-2 seconds longer before pushing over to achieve a faster descent rate. Supplemental information from acn 220937. While cruising at FL330 southwest of bna VOR on J-42 nebound, ZME gave us a turn to 360 degree from a base heading of 071 degree. With such a large heading change for no apparent reason, I suspected a traffic conflict, but none was given by ATC. In addition, our aircraft was TCASII equipped and there was no conflict shown. ATC then gave us an immediate descent to FL290 -- again no mention of conflict. When ATC issues an off-course vector while in the cruise confign, the normal response is slow and easy (ie, keep the passengers comfortable). When ATC issues a traffic conflict, the response is generally more immediate. In this situation, I never heard a traffic conflict from ATC until I was already responding to a TCASII RA. Had ATC said something about traffic at first, we could easily have provided more separation between aircraft.

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Original NASA ASRS Text

Title: AN MLG AND A WDB HAD AN LTSS THAT APPARENTLY WAS CAUSED BY PLT ERROR IN NOT STARTING TURN IN A TIMELY MANNER.

Narrative: ATC GAVE US A L TURN TO 360 DEG (APPROX 65 DEG L TURN) AND DSND TO FL290. (DSCNT WAS GIVEN FIRST, FOLLOWED BY THE TURN). WE WERE DSNDING AT APPROX 1100 FPM AND TURNING TO 360 DEG WHEN TCASII ACTIVATED AND SHOWED A RED ARC EVERYWHERE EXCEPT 1500-1800 DOWN. I TOOK ACFT FROM FO AND STEEPENED TO ABOUT 1800 FPM (SOMEWHERE IN GREEN ARC). WE SPOTTED A WDB PASSING DIRECTLY OVERHEAD ABOUT 500 FT HIGHER. WE COMPLETED TURN AND LEVELED AT FL290. TCASII GAVE US A CLR OF TFC AS WDB PASSED OVERHEAD. ATC THEN ASSIGNED A R TURN TO 090 DEG AND REINTERCEPTED J-42, AS FILED. I WAS SURPRISED TO GET A RA FROM THE TCASII (FO AND I BOTH COMMENTED ON THE SUDDEN L TURN AND DSCNT). I PERHAPS WAITED 1-2 SECONDS LONGER BEFORE PUSHING OVER TO ACHIEVE A FASTER DSCNT RATE. SUPPLEMENTAL INFO FROM ACN 220937. WHILE CRUISING AT FL330 SW OF BNA VOR ON J-42 NEBOUND, ZME GAVE US A TURN TO 360 DEG FROM A BASE HDG OF 071 DEG. WITH SUCH A LARGE HDG CHANGE FOR NO APPARENT REASON, I SUSPECTED A TFC CONFLICT, BUT NONE WAS GIVEN BY ATC. IN ADDITION, OUR ACFT WAS TCASII EQUIPPED AND THERE WAS NO CONFLICT SHOWN. ATC THEN GAVE US AN IMMEDIATE DSCNT TO FL290 -- AGAIN NO MENTION OF CONFLICT. WHEN ATC ISSUES AN OFF-COURSE VECTOR WHILE IN THE CRUISE CONFIGN, THE NORMAL RESPONSE IS SLOW AND EASY (IE, KEEP THE PAXS COMFORTABLE). WHEN ATC ISSUES A TFC CONFLICT, THE RESPONSE IS GENERALLY MORE IMMEDIATE. IN THIS SITUATION, I NEVER HEARD A TFC CONFLICT FROM ATC UNTIL I WAS ALREADY RESPONDING TO A TCASII RA. HAD ATC SAID SOMETHING ABOUT TFC AT FIRST, WE COULD EASILY HAVE PROVIDED MORE SEPARATION BTWN ACFT.

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.