AN ACR MLG CLBED IN RESPONSE TO A TCASII COMMAND.

Narrative

DURING ILS APCH PATTERN VECTORING AT 3000 FT MSL TO A RWY 23 ILS AT GREENSBORO; NC; ON AUG/FRI/93; WE ENCOUNTERED A TFC CONFLICT WITH A GA ACFT THAT WAS NOT IN CONTACT WITH GSO APCH CTL. THE CONFLICT ACFT WAS SEEN ON TCASII AT OUR ALT AND APPROX 6 MI ON A DIRECT BEARING FOR OUR ACFT. THE CONFLICT ACFT'S DISTANCE FROM US SLOWLY DECREASED UNTIL SUCH TIME THAT OUR TCASII SYS ISSUED A CLB RA. WE COMPLIED AND NOTIFIED APCH CTL. WE CLBED TO 3900 FT MSL IN THE RA MANEUVER; ADVISED THE CTLR AND DSNDED BACK TO 3000 FT MSL AS SOON AS WE ESTABLISHED CONTACT WITH ATC. THE CONFLICT ACFT WAS SEEN TO REMAIN AIRBORNE; WITHOUT RADIO CONTACT IN THE ILS APCH TFC PATTERN FOR SOME TIME AFTER WE TURNED FROM ILS DOWNWIND TO PATTERN BASE LEG. APCH CTL INDICATED THERE WERE NO TFC CONFLICTS RESULTING FROM OUR INITIATION OF THE TCASII RA MANEUVER. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE RPTING CAPT STATES THAT THERE WAS AN ACFT OUT THERE; BUT THERE WAS NO WARNING FROM APCH CTL. THE ACFT APPARENTLY WAS OUTSIDE THE ATA BUT SLIGHTLY IN THE WAY OF INCOMING ACFT. THE INTRUDING ACFT WAS NOT IN CONTACT WITH APCH CTL.