B737 ON APCH TO IAD ENCOUNTERS HELI TFC WHILE ON ILS APCH.

Narrative

WHILE ON FINAL PASSING 2000 FT AND CLRED FOR APCH INTO IAD; A BLACK HAWK PROGRESSED IN THE OPPOSITE DIRECTION OF OUR ACFT IN A CLB; APPARENTLY CLBING ON THE REVERSE OF THE ILS -- BOTH COURSE AND ALT. THE TCASII WAS THE ORIGINAL INDICATOR OF THE OTHER ACFT. I SAW THE HELI THROUGH THE HUD AND IT WAS LINED UP IN THE SIGHT OF THE HUD AND ON THE CTRLINE AND GLIDE PATH OF THE APCH. AS WE NEARED AND WATCHED; THE HELI MADE A L TURN (TO OUR R) AND PASSED TO OUR R AT VERY CLOSE PROX. AN ACTUAL DISTANCE BTWN ACFT WAS TOO DIFFICULT TO DETERMINE BUT MUCH TOO CLOSE FOR AN APCH UNDER CLOSE CTL BY THE APCH CTL. WE INITIALLY NOTIFIED THE APCH CTL OF THE OTHER ACFT AND WERE TOLD 'ROGER.' THEN WHEN THE PASS WAS TOO CLOSE FOR COMFORT; I TOLD THE CTLR 'IT WAS TOO CLOSE FOR COMFORT AND THE INCIDENT NEEDS TO BE RPTED.' THE CTLR SAID AGAIN 'ROGER.' NOT SURE OF THE EXACT WORDS; BUT NO EXPLANATION WAS GIVEN OR REASON FOR THE OTHER ACFT. NO EXPLANATION OF ANY SORT WAS GIVEN AS TO WHY THE OTHER ACFT WAS THERE OR IF THE CTLR HAD ANY KNOWLEDGE OF THE OTHER ACFT. THIS IS NOT A REASONABLE SIT ANYWHERE IN THIS COUNTRY AND IN PARTICULAR IN THE WASHINGTON AREA.