Narrative:

I was operating a helicopter over the scene of a fire at or near the above reported radial. While in a stabilized hover at approximately 1700 ft MSL, I observed a light airplane approaching from approximately 2 mi away, closing fast. I was directly facing this aircraft who appeared to be at the same altitude. I had my forward landing light and taxi light illuminated. My aircraft is equipped with a vertical fin a/C strobe and high intensity white strobes on both horizontal stabilizers. I was in radar contact, but not within the class B on an active ADIZ flight plan. I never received a traffic conflict warning from ATC. I began a right turn and immediate descent. The cessna began to turn left into my flight path and was holding altitude and closing fast. I began an immediate abrupt left turn and immediately began an automatic-rotative descent at about greater than 1800 FPM. I began an approximately 40 degree left bank and continued an automatic-rotative descent. The cessna leveled and continued into my flight path passing overhead of my starboard side at approximately 50 ft vertically and 100 ft horizontally. The cessna then began a left turn and began to orbit the fire. I stabilized my aircraft in controled flight at 1000 ft MSL. I made several calls in the blind on the traffic watch frequency 123.47. A traffic watch plane answered. He advised that he was on the same scene I was. He further stated that he was on an assigned altitude by ATC. He further stated that he never saw a helicopter hovering in his flight 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 traffic conflict warning. I advised him of the see and avoid rule despite his assigned altitude he apologized.

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Original NASA ASRS Text

Title: 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.

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.