Narrative:

I was cleared for the visibility approach approximately 15 mi out and turned over to tower. After confign, at approximately 500' AGL, the TCAS sounded the 'traffic, traffic' aural warning, and the TCAS screen (range 5 mi) showed a yellow circle directly below (behind) the aircraft symbol. The altitude was obscured by the aircraft symbol. The TCAS aural 'monitor vertical speed' immediately sounded and the yellow circle was touching the aircraft symbol. Because of the close proximity to the ground (300' AGL by this time) and the surprising TCAS alerts (because I did not know if or where there was another aircraft), I initiated a missed approach. Immediately upon advancing throttles and raising the nose, our aircraft was overtaken by a wwii vintage fighter, approximately 150' higher and 25' to the right, and perhaps 50 KTS faster. The fighter pitched out into a military overhead pattern right in front of us. Tower advised us during go around, 'he was supposed to be at 2500'.' after landing, I spoke with the tower supervisor who informed me that the intruder was a civil fgt on a VFR flight plan. The pilot had reported us in sight, but because of excessive speed requested the overhead pattern. Tower supervisor had no explanation for the fgt being at that altitude. The TCAS system is new to us all. Upon reflection I realize that because the altitude was obscured above the yellow DOT should have told me the intruder was above my aircraft, but in the heat of the moment that just didn't register. I had no warning until the intruder was on top of me, and I am concerned with the aft-looking capability, or lack therefore, of the TCAS. The RA feature was disabled below 1000' AGL. The near miss would have occurred whether or not the TCAS was installed, but our first indication would have been as the intruder passed overhead, and I most likely would have continued the approach. I feel the TCAS alerts and my misinterp of the display broke my concentration and were the basis for my decision to go around, since frankly, I had no idea what was going on and 300' AGL is no place to stop and analyze. Unfortunately, that decision almost turned the near miss into a midair collision.

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Original NASA ASRS Text

Title: CIVILIAN FGT OVERTAKES MLG ON FINAL APCH CAUSING NMAC.

Narrative: I WAS CLRED FOR THE VIS APCH APPROX 15 MI OUT AND TURNED OVER TO TWR. AFTER CONFIGN, AT APPROX 500' AGL, THE TCAS SOUNDED THE 'TFC, TFC' AURAL WARNING, AND THE TCAS SCREEN (RANGE 5 MI) SHOWED A YELLOW CIRCLE DIRECTLY BELOW (BEHIND) THE ACFT SYMBOL. THE ALT WAS OBSCURED BY THE ACFT SYMBOL. THE TCAS AURAL 'MONITOR VERT SPD' IMMEDIATELY SOUNDED AND THE YELLOW CIRCLE WAS TOUCHING THE ACFT SYMBOL. BECAUSE OF THE CLOSE PROX TO THE GND (300' AGL BY THIS TIME) AND THE SURPRISING TCAS ALERTS (BECAUSE I DID NOT KNOW IF OR WHERE THERE WAS ANOTHER ACFT), I INITIATED A MISSED APCH. IMMEDIATELY UPON ADVANCING THROTTLES AND RAISING THE NOSE, OUR ACFT WAS OVERTAKEN BY A WWII VINTAGE FIGHTER, APPROX 150' HIGHER AND 25' TO THE RIGHT, AND PERHAPS 50 KTS FASTER. THE FIGHTER PITCHED OUT INTO A MIL OVERHEAD PATTERN RIGHT IN FRONT OF US. TWR ADVISED US DURING GAR, 'HE WAS SUPPOSED TO BE AT 2500'.' AFTER LNDG, I SPOKE WITH THE TWR SUPVR WHO INFORMED ME THAT THE INTRUDER WAS A CIVIL FGT ON A VFR FLT PLAN. THE PLT HAD RPTED US IN SIGHT, BUT BECAUSE OF EXCESSIVE SPD REQUESTED THE OVERHEAD PATTERN. TWR SUPVR HAD NO EXPLANATION FOR THE FGT BEING AT THAT ALT. THE TCAS SYS IS NEW TO US ALL. UPON REFLECTION I REALIZE THAT BECAUSE THE ALT WAS OBSCURED ABOVE THE YELLOW DOT SHOULD HAVE TOLD ME THE INTRUDER WAS ABOVE MY ACFT, BUT IN THE HEAT OF THE MOMENT THAT JUST DIDN'T REGISTER. I HAD NO WARNING UNTIL THE INTRUDER WAS ON TOP OF ME, AND I AM CONCERNED WITH THE AFT-LOOKING CAPABILITY, OR LACK THEREFORE, OF THE TCAS. THE RA FEATURE WAS DISABLED BELOW 1000' AGL. THE NEAR MISS WOULD HAVE OCCURRED WHETHER OR NOT THE TCAS WAS INSTALLED, BUT OUR FIRST INDICATION WOULD HAVE BEEN AS THE INTRUDER PASSED OVERHEAD, AND I MOST LIKELY WOULD HAVE CONTINUED THE APCH. I FEEL THE TCAS ALERTS AND MY MISINTERP OF THE DISPLAY BROKE MY CONCENTRATION AND WERE THE BASIS FOR MY DECISION TO GO AROUND, SINCE FRANKLY, I HAD NO IDEA WHAT WAS GOING ON AND 300' AGL IS NO PLACE TO STOP AND ANALYZE. UNFORTUNATELY, THAT DECISION ALMOST TURNED THE NEAR MISS INTO A MIDAIR COLLISION.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.