MD80 FLC RECEIVES A TCASII RA WHILE ON 6 MI FINAL TO MCO AND EXECUTES A CLB EVASIVE MANEUVER. NO TFC OBSERVED BY FLC; BUT ADVISED ON GND CTL THAT MAINT XPONDER TESTING WAS BEING CONDUCTED AT SDF ARPT.

Narrative

WHILE ON FINAL TO RWY 18L AT MCO AND AT ABOUT 3500 FT MSL OVER THE CIVIL ARPT 6 NM N OF MCO WHILE CLRED FOR THE VISUAL APCH TO RWY 18L; WE RECEIVED AN INSTANTANEOUS CLB RA OF ABOUT 1800 FPM. WE STARTED THE CLB AND INFORMED THE TWR AND THE CLR OF CONFLICT MESSAGE FOLLOWED OUR INITIATION OF A CLB ALMOST IMMEDIATELY. WE ABANDONED THE APCH AND WITH TWR CLRNC CIRCLED BACK FOR AN UNEVENTFUL LNDG ON RWY 18L. WE NEVER SAW ANY TFC IN OUR AREA. ON TAXI IN TO THE GATE; TWR INFORMED US THAT SOMEONE HAD TESTED A XPONDER AT THE ARPT WE OVERFLEW AND THAT SIMILAR OCCURRENCES HAD BEEN EXPERIENCED IN THE PAST. HOPE THIS WILL PROVIDE A HEADS UP FOR THE FUTURE. CALLBACK CONVERSATION WITH MCO TRACON SPECIALIST REVEALED THE FOLLOWING INFO: THERE WERE KNOWN INSTANCES OF UNSHIELDED XPONDER TESTING INCIDENTS CAUSING FALSE TCASII RA'S AT AN ELECTRONIC REPAIR FACILITY AT ORL ARPT. AN MCO TRACON REPRESENTATIVE HAD CALLED THE REPAIR FACILITY QUESTIONING MAINT PRACTICES. SOMEONE AT THE ELECTRONIC REPAIR FACILITY ACKNOWLEDGED THAT SUCH UNSHIELDED INCIDENCES COULD HAVE OCCURRED.