Narrative:

With first officer flying, we were climbing slowly through FL250 to our filed cruising altitude of FL350. A TCASII TA appeared at our 12 O'clock position and 800 ft above us and closing. ATC was immediately questioned and replied that he had no conflicting traffic in our vicinity. I directed the first officer to level the aircraft as a continued climb would have put us at his altitude when we converged. TCASII directed monitor vertical speed and then an RA to descend. The first officer initiated a descent of approximately 2000 FPM. When clear of conflict we resumed our climb. Altitude loss was approximately 2000 ft. ATC indicated no loss of separation with known traffic occurred. ATC also continued to maintain that there was no conflicting traffic in our area. With numerous cumulo nimbus and cloud layers in the area, attempts to visually locate the traffic wre unsuccessful. Human factors considerations: 1) both the first officer and myself commented that ongoing simulator training of TCASII RA's would be beneficial. 2) do TCASII system provide false targets? I don't recall any information on the subject. 3) policy of not initiating avoidance prior to an RA is difficult to follow with a rapid closure rate, inability to visually locate traffic, no way of knowing if target is real or false in this case, and target's intentions.

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Original NASA ASRS Text

Title: MD88 IN CLB RECEIVED TCASII RA ON TARGET AT 12 O'CLOCK WHICH CONVERGED WITH RPTR ACFT RESULTING IN RPTR DSNDING 2000 FT UNTIL 'CLR OF CONFLICT.' CTLR RPTED NO CONFLICTING TFC IN THE AREA.

Narrative: WITH FO FLYING, WE WERE CLBING SLOWLY THROUGH FL250 TO OUR FILED CRUISING ALT OF FL350. A TCASII TA APPEARED AT OUR 12 O'CLOCK POS AND 800 FT ABOVE US AND CLOSING. ATC WAS IMMEDIATELY QUESTIONED AND REPLIED THAT HE HAD NO CONFLICTING TFC IN OUR VICINITY. I DIRECTED THE FO TO LEVEL THE ACFT AS A CONTINUED CLB WOULD HAVE PUT US AT HIS ALT WHEN WE CONVERGED. TCASII DIRECTED MONITOR VERT SPD AND THEN AN RA TO DSND. THE FO INITIATED A DSCNT OF APPROX 2000 FPM. WHEN CLR OF CONFLICT WE RESUMED OUR CLB. ALT LOSS WAS APPROX 2000 FT. ATC INDICATED NO LOSS OF SEPARATION WITH KNOWN TFC OCCURRED. ATC ALSO CONTINUED TO MAINTAIN THAT THERE WAS NO CONFLICTING TFC IN OUR AREA. WITH NUMEROUS CUMULO NIMBUS AND CLOUD LAYERS IN THE AREA, ATTEMPTS TO VISUALLY LOCATE THE TFC WRE UNSUCCESSFUL. HUMAN FACTORS CONSIDERATIONS: 1) BOTH THE FO AND MYSELF COMMENTED THAT ONGOING SIMULATOR TRAINING OF TCASII RA'S WOULD BE BENEFICIAL. 2) DO TCASII SYS PROVIDE FALSE TARGETS? I DON'T RECALL ANY INFO ON THE SUBJECT. 3) POLICY OF NOT INITIATING AVOIDANCE PRIOR TO AN RA IS DIFFICULT TO FOLLOW WITH A RAPID CLOSURE RATE, INABILITY TO VISUALLY LOCATE TFC, NO WAY OF KNOWING IF TARGET IS REAL OR FALSE IN THIS CASE, AND TARGET'S INTENTIONS.

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.