POSSIBLE FALSE TCASII ALARM; POSSIBLE LTSS IN THE TFC PATTERN.

Narrative

WE WERE CLRED FOR TKOF ON RWY 18L AT DFW WITH A 185 DEG HDG AT THE MARKER. AFTER FLAPS UP AND CLB PWR; WE RECEIVED AN RA SHORTLY AFTER 1000 FT AGL. TARGET WAS LESS THAN 1 MI AT 3 O'CLOCK AND 100 FT ABOVE. TCASII GAVE 1 'DSND' AND COMMANDED MASSIVE (1200 FT PLUS) RATE DOWN. THERE NEVER WAS ANOTHER 'DSND;' 'MONITOR VERT SPD' OR CLR OF CONFLICT.' NEITHER TWR OR DEP HAD ANY TFC IN OUR AREA AT THE TIME. SUPPLEMENTAL INFO FROM ACN 310543: WE NEVER HAD VISUAL CONTACT AND ONLY HAD THE 1 VERBAL COMMAND FROM TCASII. DEP CTL ONLY HAD THE WBOUND COMMUTER ON RADAR. CALLBACK CONVERSATION WITH RPTR FROM ACN #310543 REVEALED THE FOLLOWING INFO FROM 310543: THE RPTR WAS THE NON- FLYING CAPT ON THIS TRIP. HE HAS BEEN SO PLEASED WITH TCASII AND ITS OP THAT HE NEVER CONSIDERED THE POSSIBILITY OF A FALSE ALARM. HE NOW AGREES THAT THIS COULD HAVE BEEN THE SIT AS NEITHER HE; THE FLYING FO; NOR ATC SAW ANY OTHER TFC. THE WX WAS 'GOOD;' HE 'SHOULD HAVE BEEN ABLE TO SEE ANY TFC.' THE TCASII WAS NOT WRITTEN UP IN THE LOGBOOK AS THE RPTR DID NOT CONSIDER A FALSE ALARM.