EMS HELI PENETRATES ATA WITHOUT CLRNC.

Narrative

ACFT WAS ENRTE TO A TFC ACCIDENT IN ZZZ. NORMAL NAV IS WITH LORAN; BUT ON THIS PARTICULAR FLT IT WASN'T FUNCTIONING. AS IS NORMAL ON THESE FLTS TO SCENE CALLS; WE RECEIVED CURRENT LOCATION (LAND ZONE) INFO FROM THE EMS GND UNITS. HOWEVER; THERE WAS A SHORT PERIOD OF TIME WHILE WE WERE LOOKING FOR THE LOCATION WITH INCORRECT INFO; AND THE ACFT PENETRATED THE S EDGE OF ZZZ'S ATA. I HAD THE ARPT IN SIGHT BUT DIDN'T REALIZE I WAS THAT CLOSE UNTIL I NOTICED THE DME. THERE WAS NEVER ANY CONFLICT WITH OTHER ACFT. THE SCENE WAS LOCATED AND THE MISSION WAS COMPLETED. AFTER DEPARTING THE HOSPITAL ENRTE BACK TO HOME STATION; I CALLED ZZZ TWR AND EXPLAINED WHAT HAPPENED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT THIS MISSION WAS BEING FLOW FOR ANOTHER COMPANY WHO WAS TOO BUSY TO TAKE THIS FLT. RPTR WAS NOT AS FAMILIAR WITH THIS AREA AND CONFUSION OCCURRED DUE TO INCORRECT LOCATION INFO BEING GIVEN ABOUT SCENE. THIS DISTRACTED PLT AND INADVERTENTLY ENTERED NEARBY ATA. COMPANIES IN AREA OFTEN USE DISCRETE XPONDER CODES DESIGNATED TO EACH COMPANY BY ATC. THEREFORE; THE ATC 'KNEW' THIS ACFT WAS IN THE VICINITY WITHOUT ANY PRIOR COM.