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Last night it was a case of lowering cloud deck - we agreed that if we had to go >2500AGL we would try this trick. Minutes later we saw a black out of ground lights and rightly assumed it was a big at cloud.
So, I called them (Bravo ATC APP) and requested the transition - he responded as though he gets 50 such requests a day and told us what we had to do.
Student really liked the technique - and it's comforting to know that if you're out on a VFR and clouds roll in, you can switch over in a jiffy so long as you have a nice controller.
Worst case would be having to circle in VMC whilst you chat to FSS - which aint so bad either.
I love learning and more importantly putting into use these little tricks or "tools" - increases confidence many many times over!
Safe flying!