On Sep 4, 4:50*am, a wrote:
On Sep 4, 12:33*am, "Nick Naim" wrote:
..........

they fly in controlled airspace

He points out he is looking for traffic before he does it
(though at Heathrow I believe they are in class A from
the ground). It's less than a second for the whole
transition, hardly any time you can't see out.