I've never heard of anybody trying this as a reason for a CAS transit. I am pretty sure that quite a few ATC units would give you a short thrift, especially some overseas ones, unless you declared an emergency
My logbook tells me that on 8.1.2000, while ferrying my a/c back from its 50 hr from N Weald to the strip near Honington, I asked Stansted for a zone transit (to avoid going round 3 sides of a square).
It was of course refused.
Five minutes later, travelling to the east towards Chelmsford it was plain to me that my path was completely blocked by a mass of CBs and rain.
I put this to Essex Radar who immediately cleared me through Stansted zone and along the line of the runway, not across it.
Never been granted a transit since, to the extent I've given up asking.
But it can be done for Wx.
Cusco
