Narrative:

Cruising at FL240, we received an RA for traffic to descend. The captain complied and I reported it to ATC. After we were clear of traffic, we climbed back to FL240. Total altitude deviation was approximately 900 ft. The other aircraft leveled at FL250 as cleared. Suspect excessive descent rate of other aircraft was the problem.

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Original NASA ASRS Text

Title: A CL600 ACR CREW DSNDS 900 FT BELOW THEIR ASSIGNED CRUISE ALT WHEN THEIR TCASII SENSES A RAPIDLY DSNDING ACFT LEVELING 1000 FT ABOVE 35 MI SE OF FLM, KY.

Narrative: CRUISING AT FL240, WE RECEIVED AN RA FOR TFC TO DSND. THE CAPT COMPLIED AND I RPTED IT TO ATC. AFTER WE WERE CLR OF TFC, WE CLBED BACK TO FL240. TOTAL ALTDEV WAS APPROX 900 FT. THE OTHER ACFT LEVELED AT FL250 AS CLRED. SUSPECT EXCESSIVE DSCNT RATE OF OTHER ACFT WAS THE PROB.

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.