without seeing it i couldnt say for sure. i know the turbulane generated by rotor wash is pretty easy to see with my small electric helis in the house. and im sure if you flew over or under a larger heli it could directly effect a planes stability from rotor wash if you were close. no idea what it could be. i doubt it would be frequency becuase it was intermitant and usually radio hits are pretty violent when someone is on same channel and thinks there not. could it be a loss of signal because you were really far out with a micro reciever ? ive seen micro recievers rated for 600 feet opposed to regular recievers rated to 2500 feet. ive run a gws rated for lower range but never had problems and i think its rated for 600 feet but would have to check.