FLC RPTS ERRONEOUS READOUTS FROM TCASII TA RA'S ON NON INTRUDER ACFT.

Narrative

OUR ASSIGNED ALT WAS 10000 FT MSL AND WE HAD JUST PASSED 9000 FT WITH A VVI OF 500 FPM AND AN IAS OF 240 KTS. AS WE APCHED 9500 FT; TCASII ISSUED A TA FOR A TARGET AT 2 O'CLOCK; 5 MI; 900 FT BELOW US. APCHING 10000 FT TCASII ISSUED AN RA -- 'MONITOR VERT SPD;' FOLLOWED ALMOST IMMEDIATELY BY 'CLB; CLB; CLB.' THE RA MODE THEN SHIFTED TO 'CLB; XING CLB' AND DIRECTED A CLB OF OVER 2000 FPM. ALTHOUGH THE WX WAS EXCELLENT; WE WERE UNABLE TO SEE ANY TFC IN THE 1-2 O'CLOCK POS BECAUSE WE WERE LOOKING STRAIGHT INTO THE LATE AFTERNOON SUN. WE FOLLOWED TCASII GUIDANCE -- PER COMPANY PROCS -- THROUGH OUR ASSIGNED ALT TO APPROX 10800 FT. WE THEN SAW OUR TFC COMING OUT OF THE SUN AT 1-2 O'CLOCK. IT WAS AN MD-88 IN A L TURN ABOUT 1/2 MI AWAY AND ABOVE US. THIS OTHER AIRPLANE; WE LATER LEARNED; WAS AT 11000 FT THROUGH THE ENTIRE ENCOUNTER. BOTH THE PNF AND THE JUMPSEAT OBSERVER CONFIRMED THAT THE ORIGINAL TA AND RA WERE ISSUED ON A TARGET DISPLAYED ON THE SCREEN AS BELOW US. THE TFC WE EVENTUALLY SAW WAS ABOVE US THE ENTIRE TIME.