NMAC AT 1300 FT BTWN AN AS-350B AND A C172 OVER THE SCENE OF A FIRE IN THE DC ADIZ AREA NW OF BAL; MD.

Narrative

I WAS OPERATING A HELI OVER THE SCENE OF A FIRE AT OR NEAR THE ABOVE RPTED RADIAL. WHILE IN A STABILIZED HOVER AT APPROX 1700 FT MSL; I OBSERVED A LIGHT AIRPLANE APCHING FROM APPROX 2 MI AWAY; CLOSING FAST. I WAS DIRECTLY FACING THIS ACFT WHO APPEARED TO BE AT THE SAME ALT. I HAD MY FORWARD LNDG LIGHT AND TAXI LIGHT ILLUMINATED. MY ACFT IS EQUIPPED WITH A VERT FIN A/C STROBE AND HIGH INTENSITY WHITE STROBES ON BOTH HORIZ STABILIZERS. I WAS IN RADAR CONTACT; BUT NOT WITHIN THE CLASS B ON AN ACTIVE ADIZ FLT PLAN. I NEVER RECEIVED A TFC CONFLICT WARNING FROM ATC. I BEGAN A R TURN AND IMMEDIATE DSCNT. THE CESSNA BEGAN TO TURN L INTO MY FLT PATH AND WAS HOLDING ALT AND CLOSING FAST. I BEGAN AN IMMEDIATE ABRUPT L TURN AND IMMEDIATELY BEGAN AN AUTO-ROTATIVE DSCNT AT ABOUT GREATER THAN 1800 FPM. I BEGAN AN APPROX 40 DEG L BANK AND CONTINUED AN AUTO-ROTATIVE DSCNT. THE CESSNA LEVELED AND CONTINUED INTO MY FLT PATH PASSING OVERHEAD OF MY STARBOARD SIDE AT APPROX 50 FT VERTLY AND 100 FT HORIZLY. THE CESSNA THEN BEGAN A L TURN AND BEGAN TO ORBIT THE FIRE. I STABILIZED MY ACFT IN CTLED FLT AT 1000 FT MSL. I MADE SEVERAL CALLS IN THE BLIND ON THE TFC WATCH FREQ 123.47. A TFC WATCH PLANE ANSWERED. HE ADVISED THAT HE WAS ON THE SAME SCENE I WAS. HE FURTHER STATED THAT HE WAS ON AN ASSIGNED ALT BY ATC. HE FURTHER STATED THAT HE NEVER SAW A HELI HOVERING IN HIS FLT PATH NOR WAS AWARE THAT I HAD TO TAKE EVASIVE ACTION. HE SAID THAT HE NEVER SAW ME AT ALL. I DID NOT HEAR ATC GIVE HIM A TFC CONFLICT WARNING. I ADVISED HIM OF THE SEE AND AVOID RULE DESPITE HIS ASSIGNED ALT HE APOLOGIZED.