Narrative:

While in 60 KT cruise over a river and surrounding wetlands I was headed north. At this time I was at approximately 200 ft AGL. I then noticed the cessna inbound, to my right, still a mi out, but at approximately 500 ft AGL and headed to intersect my forward path. I executed a slow stop as an avoidance procedure and brought the helicopter to an out-of-ground-effect hover while reducing my altitude to about 100 ft AGL. The cessna passed directly to my 12 O'clock position approximately 200 ft above. The cessna then made a tight 270 degree turn-about-a-point (in this case a turn-about-a hovering helicopter) with bank angles clearly in excess of 45 degrees as it orbited my helicopter. Already in a hover I completed a 270 degree pedal-turn and visually followed the cessna around until it broke off and flew away. If either of us had lost visual contact and incorrectly guessed the other's intentions a midair collision might have occurred. I don't think this represents an near midair collision, however, as I maintained strict visual separation from this aircraft, the cessna pilot intentionally 'buzzed' another aircraft. Moments later I attempted to reach the cessna on C122.8 frequency, this time with success. The pilot idented their registration number and indicated that they were state police engaged in an operation. This operation was mi away from my flight path when the turn-about-a-helicopter occurred and the cessna subsequently returned to where their activity was taking place.

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Original NASA ASRS Text

Title: R44 PLT QUESTIONS THE SAFETY OF A POLICE ACFT MAKING A TURN OVER HIS HELI APPARENTLY FOR IDENT PURPOSES.

Narrative: WHILE IN 60 KT CRUISE OVER A RIVER AND SURROUNDING WETLANDS I WAS HEADED N. AT THIS TIME I WAS AT APPROX 200 FT AGL. I THEN NOTICED THE CESSNA INBOUND, TO MY R, STILL A MI OUT, BUT AT APPROX 500 FT AGL AND HEADED TO INTERSECT MY FORWARD PATH. I EXECUTED A SLOW STOP AS AN AVOIDANCE PROC AND BROUGHT THE HELI TO AN OUT-OF-GND-EFFECT HOVER WHILE REDUCING MY ALT TO ABOUT 100 FT AGL. THE CESSNA PASSED DIRECTLY TO MY 12 O'CLOCK POS APPROX 200 FT ABOVE. THE CESSNA THEN MADE A TIGHT 270 DEG TURN-ABOUT-A-POINT (IN THIS CASE A TURN-ABOUT-A HOVERING HELI) WITH BANK ANGLES CLRLY IN EXCESS OF 45 DEGS AS IT ORBITED MY HELI. ALREADY IN A HOVER I COMPLETED A 270 DEG PEDAL-TURN AND VISUALLY FOLLOWED THE CESSNA AROUND UNTIL IT BROKE OFF AND FLEW AWAY. IF EITHER OF US HAD LOST VISUAL CONTACT AND INCORRECTLY GUESSED THE OTHER'S INTENTIONS A MIDAIR COLLISION MIGHT HAVE OCCURRED. I DON'T THINK THIS REPRESENTS AN NMAC, HOWEVER, AS I MAINTAINED STRICT VISUAL SEPARATION FROM THIS ACFT, THE CESSNA PLT INTENTIONALLY 'BUZZED' ANOTHER ACFT. MOMENTS LATER I ATTEMPTED TO REACH THE CESSNA ON C122.8 FREQ, THIS TIME WITH SUCCESS. THE PLT IDENTED THEIR REGISTRATION NUMBER AND INDICATED THAT THEY WERE STATE POLICE ENGAGED IN AN OP. THIS OP WAS MI AWAY FROM MY FLT PATH WHEN THE TURN-ABOUT-A-HELI OCCURRED AND THE CESSNA SUBSEQUENTLY RETURNED TO WHERE THEIR ACTIVITY WAS TAKING PLACE.

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.