To everyone downvoting me for suggesting that he should have enabled failsafe
I am sick of people who are ignorant of R/C down-voting me, so have withdrawn my original post.
It's a LEGAL REQUIREMENT under CAA law CAP658 that you must enable failsafe (Turn motors off) in the event of a loss of control link if your equiment supports it (Which nearly everything does)
So if this dickhead let his 1.7m behemoth happily fly off into the sunset and come down some distance away with the engine still running, he is entirely at fault, whether jammers were involved or not.
The BMFA (Which this guy was almost certainly a member of) guidelines clearly lay out the rationale behind this:
"The fitment of a failsafe performs three vital functions in the event of a loss or corruption of the R/C signal.
The primary purpose is to reduce the potential energy of an aircraft that is no longer responding to commands from the transmitter and is therefore likely to crash.
Taking away the propulsion source can significantly reduce the energy of any impact thereby reducing the potential for injury or damage.
Secondly, the closing of the throttle on loss of signal serves to significantly reduce the potential radius of the impact area, with the primary aim that any impact will be on the “live” side of the flying activity; this is particularly important at displays and public events but also relevant at the club field.
The third aspect of the closing of the throttle is that it prevents an out of control model aircraft from climbing once the signal has been lost and presenting a hazard to full size aircraft or entering controlled airspace."
This has NOTHING to do with autonomy - your model does not need autonomy to do this, it's a feature of the R/C control link
TLDR you put the safety of other people first - if this means that your model gets wrecked, so be it - that's a part of the hobby that us UAV pilots must deal with.