Narrative:

Had clearance to 16000 ft, passing through FL210 at approximately 2500 FPM descent, we were told to maintain FL210. By this time we were approaching FL200 and I questioned the clearance as we started to slow the descent and climb back to FL210. As we did, we received an RA with a 2000 FPM descent command. With the traffic not in sight we followed the command. At approximately FL195 we were clear of the conflict and advised ATC. We were then reclred to 11000 ft. It looked to us as the initial clearance, with our rate of descent, would have kept us clear of any conflict. The conflict arose with the reclearance to maintain an altitude we had just passed through.

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Original NASA ASRS Text

Title: LOSS OF SEPARATION BTWN AN ACR DSNDING THROUGH FL210 AND OTHER ACFT PRESUMED TO BE AT OR CLBING TO FL200. RPTR STATED THEY RECEIVED A TCASII RA TO DSND AND WERE CLR OF THE TFC AT FL195.

Narrative: HAD CLRNC TO 16000 FT, PASSING THROUGH FL210 AT APPROX 2500 FPM DSCNT, WE WERE TOLD TO MAINTAIN FL210. BY THIS TIME WE WERE APCHING FL200 AND I QUESTIONED THE CLRNC AS WE STARTED TO SLOW THE DSCNT AND CLB BACK TO FL210. AS WE DID, WE RECEIVED AN RA WITH A 2000 FPM DSCNT COMMAND. WITH THE TFC NOT IN SIGHT WE FOLLOWED THE COMMAND. AT APPROX FL195 WE WERE CLR OF THE CONFLICT AND ADVISED ATC. WE WERE THEN RECLRED TO 11000 FT. IT LOOKED TO US AS THE INITIAL CLRNC, WITH OUR RATE OF DSCNT, WOULD HAVE KEPT US CLR OF ANY CONFLICT. THE CONFLICT AROSE WITH THE RECLEARANCE TO MAINTAIN AN ALT WE HAD JUST PASSED THROUGH.

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.