MLG HAS TCASII RA ON CLB OUT.

Narrative

WE WERE CLRED TO 10000 FT MSL AND TO JOIN THE GENEVA 1 DEP AT DETROIT. APPROX 5-8 MINS AFTER TKOF A TCASII ADVISORY WAS RECEIVED (9300 FT MSL). THE DISPLAY SHOWED A 1/2 AMBER CIRCLE AT OUR 1 O'CLOCK POS; NO ALT SHOWN. VERT SPD WAS REDUCED TO 500 FPM. AT 9700 FT MSL AN RA WAS RECEIVED SAYING 'MONITOR VERT SPD' AT WHICH POINT THE CAPT LEVELED ACFT. DISPLAY SHOWING RED BAND FOR CLB. SECONDS LATER A SECOND RA WAS ISSUED 'DSND; DSND NOW.' THE NOSE WAS LOWERED TO GREEN BAND AND DSCNT WAS MADE TO 9200 FT MSL. NO VISUAL SIGHTING OF TFC WAS MADE. AT 9300 FT MSL I NOTIFIED ATC OF THE EVENT. THE DEP CTLR SAID THERE WAS NO CONFLICT AND THE ACFT IN QUESTION IS LEVEL AT 11000 FT MSL AND HAS BEEN SO FOR 20 MI. AT THE TIME OF OUR DSCNT THE TCASII DISPLAY SHOWED INTRUDER AT OUR 1 O'CLOCK POS; RED SQUARE WITH ARROW INDICATING DSNDING. THEY WERE IN A DSCNT AT GREATER THAN 500 FPM. DUE TO THE CONFUSION IN INFO THAT WE RECEIVED FROM TCASII/ATC; THE VOICE RECORDER CIRCUIT BREAKER WAS PULLED TO RETAIN THE TCASII INFO FOR FURTHER STUDY. POSSIBLE REASONS: 1) OTHER ACFT MAY HAVE HAD THEIR OWN RESOLUTION AND WERE EXECUTING IT. 2) THE TIME FRAME WAS SO QUICK THAT THE TCASII UNIT COULD NOT KEEP UP WITH EVENT. 3) TCASII WORKED WELL; BUT COULD NOT TELL WE WERE GOING TO LEVEL AT 10000 FT.