On a flight back from Cornwall back to Cambridge yesterday, I got the usual excellent service from a chain of LARS (and non-LARS) units.
One minor event made me ponder altimeter setting procedures at Brize, though.
Over Oxford, approaching WCO at FL50, I wanted to descend to get beneath the Luton CTA. I asked specifically for the Brize QNH and said I was descending to altitude 3300 ft. In response I was given the
Cotswold QNH and asked to report level at 3300 ft, which I duly did.
At WCO I was asked to freecall Luton, and on this particular occasion had no difficulty establishing contact and getting the Luton QNH, which was a good 8 mbar higher than the Cotswold. That, of course, put me above the 3500 ft base of the approaching Luton CTA. Even if Brize didn't have a London QNH, the Brize QNH would have been much closer than the Cotswold, which, as a forecast lowest QNH for a large region and a whole hour, is often significantly lower than the actual QNH. I have no doubt that the Brize controller was procedurally correct in asking me to fly on the Cotswold QNH, even though my procedure is to set a local QNH whenever possible.
So, can I
choose my altimeter setting in class G -- though I appreciate it might make separation under RAS difficult -- and if not, what's the best way to handle such a situation?