Anyone AT controller:
Descending into Heathrow, passing, let's say, FL080, I am instructed to descend to 4000 feet. Usually, we set the QNH at the present level and start descent. Now, what if I am climbing out of Heathrow and passing 3000 feet, instructed to climb to FL110. Do I set my QNE right at the present altitude or I wait till 6000 (transition alt.) to set it?
I had this issue on a recent departure from that airport.
Appreciate any answers