AN ACR DC9 CAPT RPTS WITNESSING AN NMAC BTWN 2 SIGHTSEEING HELIS WHO WERE DEPARTING AT THE SAME TIME TOWARD THE ACR TERMINAL.

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WE WITNESSED THE FOLLOWING; BUT POTENTIALLY COULD HAVE BEEN INVOLVED. THE RAMP AT ITO IS NOT CTLED BY ATC. ACRS OPERATE ADJACENT TO A COMMUTER RAMP THAT IS PRIMARILY USED BY TOUR HELI OPS. 2 TOUR HELIS DEPARTED SIMULTANEOUSLY AS WE BEGAN TO PULL OUT OF OUR SPOT AT THE GATE. WE CALLED FOR A TAXI CLRNC (WHILE STILL IN THE UNCTLED AREA). TWR DID NOT HAVE A CHANCE TO RESPOND TO US AS HELI 'A' CAME ON THE FREQ AND INQUIRED WHERE HELI 'B' WAS GOING. THEY APPEARED TO BE ON A CONVERGING COURSE AND BOTH HDG IN OUR DIRECTION. THIS IS NORMAL DEP FLOW AND THEY ARE USUALLY INSTRUCTED TO NOT OVERFLY US -- THOUGH I HAVE NOT SEEN 2 DEPART AT THE SAME TIME BEFORE. HELI 'B' PROCEEDED IN AND HELI 'A' TOOK THE DIVERSIONARY ACTION. WE DIDN'T HEAR THE COMS TO TWR PRIOR TO OUR OWN MOVEMENT; SO WE DON'T KNOW HOW THESE 2 SIMULTANEOUS DEPS CAME ABOUT; BUT THIS CONFINED AREA PROBABLY OUGHT TO BE A CTLED MOVEMENT AREA. WE CAME TO A STOP WHEN TWR DIDN'T ANSWER; BUT DIDN'T HAVE ANY OPTION OUT OF THIS IF HELI 'A' HAD NOT TURNED AWAY.