B757 SIGHTS MIL HELI WHILE ENTERING LNDG TRANSITION MANEUVER AT DCA.

Narrative

WE WERE EXECUTING AN ILS IN IMC. AS MY FO ANNOUNCED 'APCHING MINIMUMS; RWY IN SIGHT;' I BEGAN MY TRANSITION FROM FLT DIRECTOR REF TO VISUAL REF FOR A HAND FLOWN LNDG. MY AIRSPD WAS PROBABLY AROUND 130-135 KIAS. AS I WAS TRANSITIONING I SUDDENLY SAW A DARK COLORED MIL HELI ON MY APCH PATH. HE BLENDED IN VISUALLY WITH THE DISMAL WX CONDITIONS. I DID NOT NOTICE ANY ACFT LIGHTING. AS I SAW HIM; SO DID THE DCA TWR CTLR. THE CTLR ISSUED AN IMMEDIATE AND FORCEFUL ATC INSTRUCTION TO THE HELI. THE HELI EXECUTED AN ABRUPT EVASIVE MANEUVER AND DISAPPEARED INTO THE FOG. I LANDED SAFELY. THIS ENTIRE EVENT LASTED ABOUT 3-4 SECONDS. MY ACFT (BOEING 757) CONFIGN WAS GEAR DOWN; FULL 30 DEG FLAPS; ON SPD; ON COURSE; ON GLIDE PATH. EVASIVE MANEUVERING CAPABILITY IS LIMITED UNDER THESE CIRCUMSTANCES. MY ALT WAS ABOUT 300-400 FT ABOVE THE POTOMAC RIVER. ARPT TERMINALS AND CTL TWR WERE TO MY L; PROHIBITED AREA P-56 WAS TO MY R; AND THE HELI IN QUESTION WAS IN THE WX IN FRONT OF ME SOMEWHERE. I DIDN'T FEEL I COULD EXECUTE A MISSED APCH WITH THAT ACFT IN THE FOG IN FRONT OF ME. WE WERE STILL ON LNDG PROFILE AND I DECIDED LNDG WAS THE SAFEST COURSE AVAILABLE. WE MADE A NORMAL EXIT FROM THE RWY TO THE L WITH MUCH LNDG ROOM LEFT ON RWY 36. TAXIED TO THE GATE AND PARKED. MADE AN IMMEDIATE PHONE CALL TO THE TWR SUPVR AND RPTED THE INCIDENT. THEN CALLED MY AIRLINE FLT MGMNT SUPVRS AND RPTED THE INCIDENT AND MADE A WRITTEN RPT TO THE AIRLINE SAFETY DEPT UPON ARR AT MY BASE THAT NIGHT. I AM GLAD THE VISIBILITY WAS GOOD ENOUGH FOR THE CTLR TO SEE THE HELI IN TIME TO TAKE ACTION. IF THE VISIBILITY HAD BEEN ANY LESS HE WOULDN'T HAVE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT DURING HIS SPEAKING WITH THE TWR FACILITY AT DCA; A CTLR IN TRAINING WAS HANDLING THE MIL TFC AT THE N END OF THE ARPT UNDER THE JURISDICTION OF ANOTHER; MORE EXPERIENCED; CTLR. THE SECOND CTLR IS THE ONE THAT TOOK OVER THE MIKE AND ORDERED THE HELI TO LEAVE THE APCH ENVIRONMENT OF THE LNDG TFC. THE RPTR STATES THAT HIS TRAINING WOULD NORMALLY CAUSE HIM TO EXECUTE A MISSED APCH BUT THAT THE POSSIBILITY OF ANOTHER ENCOUNTER WITH THE SAME ACFT SEEMED LIKE A GOOD POSSIBILITY AND SO DECIDED THAT LNDG WAS THE SAFEST PATH TO FOLLOW. HE SAID THAT THE PHONE CONVERSATION REVEALED THAT EXTENSIVE TRAINING FOR A MIL EXERCISE OR OP WAS IN PROGRESS AND WAS BEING STAGED FROM THE N PART OF THE DCA COMPLEX. THE RPTR DOESN'T KNOW WHETHER THE HELI PLT MISUNDERSTOOD HIS INSTRUCTIONS OR WHETHER THE CTLR ISSUED SUCH INSTRUCTIONS IN THE FIRST PLACE.