You are right - I filmed those rocks many times before, now it was an attempt to go thru the ceiling of the cave but signal start dropping and I missed itTo be honest, with the number of swifts/swallows/martins around there I think you should have called it a day earlier, I know they are superb fliers but a couple of flybys looked rather too close.
I also get the impression that this was more an attempt to fly an natural obstacle course than a look at scenic rocks.
Sorry.