Perhaps the mods here could merge the linked thread with this? In the meantime, slightly modified from that thread, is my post
BA's procedure (737) is to set 1013 when above acceleration altitude (normally 1500' QFE) and cleared to a FL (no mention of within 2000'), but the standby remains on QNH until above MSA and TA, so is normally available for an altitude check
To add: my understanding is that a common (UK) SOP is as above, with the addition that the standby is set to destination (or area?) QNH when dropping out of RVSM airspace. To add to LEM's point regarding approach checks - in my experience these are done when cleared to an altitude, not at TL.
A question on US procedures, since no-one appears to have answered 'DFC's' question. If you were to fly 1000 miles at 15000ft, do you constantly change the altimeter setting along the route and if so when and from where does the info come?
As a final point I agree with Captain Peacock that "A good dose of Commanders discretion required" since one size rarely fits all all the time.
