Hi Folks, it depends - in a Jet Ranger - no, there is nothing to interfere with ;-) But the more technic is in - like FADEC - better switch it off. It also depends of the position - og the phone and the helicopter. The closer to the fadec - and the further away from a mobile telephone ground station - the higher is the risk, that you might get problems. Another problem not mentioned yet is, that with a mobile phone - high up in the sky, the mobile provider gets upset a little bit, because your mobile phone is communicating with a lot of stations - and they have to communicate witch each other - to find out, to which mobile ground station takes over the mobile phone. This extra traffic can spoil the providers day - imagine a 747 - all passengers with their mobiles on ..... Normaly only two or three stations have to sort out, who's logging in the phone. Greetings "Flying Bull"