If you are flying a helicopter, there is no way to initiate roleplay on that helicopter but you are still a threat. The way this is worked around is that you can use tracers fired near the helicopter in order to warn them to leave. If you are given ample to to comply and do not leave they are within their right to take you out of the sky. Normally words do need to be spoken but you can't roleplay 100m up in the air so there has to be a workaround.
Short answer is yes it is initiation but if you leave the area but stay sort of nearby they would have to warn you again because you have complied and would therefore need warning a second time. If you instead chose to land when given warning shots they cannot shoot you. They would have to begin roleplay with you. To follow up, if they begin firing and you land, it cannot be considered initiation upon your person and only upon the vehicle therefore they cannot continue to shoot after you land, even if they already gave warnings and began shooting to disable. Due to the fact you are only initiating on the helicopter, you can't use it as an excuse to begin combat on the ground either.
It is a grey area to say the least but some recent player reports have set a precedent as to how this is handled.
