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.