Yet SAR helicopters have been operating in the mountains in, around and below the zero degree isotherm in mixed precipitation for many years but there are no reports of triggered lightning.
The met office and caa pages highlight that overland there is usually sufficient electrical potential to trigger a lightning strike without needing a helicopter to initiate it whereas, over the sea, the cloud can be charged but not sufficiently to discharge cloud to cloud or cloud to ground - that is when the helo comes along with a vastly different electrical polarity and triggers the strike.
Well firstly, if you look at the number of offshore oil support flights / hours per year, and then the number of triggered lightning strikes - around 1 or 2 a year on average IIRC, and then look at the number of onshore mil SAR flights / hours per year, you will see than on probability alone it is not surprising that there has not been a mil SAR triggered lightning strike.
I also think that a low flying helicopter is less likely to be a trigger because if there is that much electric field strength near the ground, an air to ground strike is likely to happen anyway. But I think for a heli flying at say 3000' agl the probabilities are much the same onshore as offshore. Yes there is a throwaway line about "usually" onshore, but I don't see any science behind that view.
Personally I think it was a mistake to decline training because of this risk, since there would inevitably be a publicity backlash, however I was in the Cairngorms on Sunday afternoon and there was one massive snowstorm all afternoon which closed the Lecht and the A96 and that for me would have been good enough reason to stay cosy in Ops unless I really had to go flying!