A little off topic, but I also do metal detecting and have a couple of pretty nice detectors . Several times I.ve been asked to find something for someone thats fallen of a plane or heli. Always worried about shooting someone down with it, so I only search when there is no flying going on.
I did aim both coils at my plane sitting on the ground turned on ,to see if it messed with it , no problems . 2.4g Spektrum . Haven't tried it onFM or other 2.4g .