UNAUTH OP OVER AN ACCIDENT SCENE WITH ROTARY WINGED TFC IN AREA PERFORMING AMBULANCE SVC.

Narrative

I WAS CIRCLING THE SCENE OF A SERIOUS ACCIDENT AND RPTING MY OBSERVATIONS TO A GND STATION. FROM PAST EXPERIENCE OF RPTING ON SUCH SERIOUS ACCIDENTS; I REALIZED THE POSSIBILITY OF THE NEED FOR AN EMS HELI. AS I MADE MY THIRD TURN OVER THE SCENE SINCE ARRIVING; I NOTICED AN INBOUND CHOPPER FROM THE SW AT A HIGHER ALT. UPON SEEING THE CHOPPER I IMMEDIATELY DEPARTED THE SCENE TO THE S TO ALLOW THE CHOPPER TO LAND WITHOUT ANY INTERFERENCE. AFTER WATCHING THE CHOPPER LAND; I RETURNED TO THE SCENE OF THE ACCIDENT. A FEW MINS LATER; ANOTHER CHOPPER ARRIVED AND PROCEEDED TO SET DOWN. AT THIS POINT I DECIDED A NEWS AND TFC RPT WAS MUCH LESS IMPORTANT THAN THE PURPOSE THESE HELIS HAD SO I DEPARTED AND HEADED FOR MY BASE. LATER THAT EVENING I LEARNED THAT THE FIRST HELI BELIEVED I WAS CIRCLING AT AN ALT OF 500 FT MSL WHICH WOULD BE ABOUT 300 FT AGL. DUE TO THE TURB PRESENT; I MAY HAVE BEEN AT 900 FT MSL (700 FT AGL) FOR A SHORT TIME. THE LCL AREA WAS SPARSELY POPULATED WHICH MAKES THE MINIMUM ALT 500 FT AGL WHICH I WAS CERTAINLY ABOVE. I BELIEVE THE HELI PLT UNDERESTIMATED MY ALT DUE TO HIS BEING ABOVE ME. I THINK A SPECIFIC FREQ SET UP FOR SITS LIKE THIS BTWN NEWS AND TFC ACFT AND OTHER OFFICIAL ACFT WOULD QUICKLY SOLVE THIS PROB. THE FREQ COULD BE USED AS A CTAF FOR SUCH SITS IF DISSEMINATED TO ALL PLTS INVOLVED.