"Alan White" wrote in message
...

That's what I meant by 'flying at a pressure altitude'.

Yes, I guess I was splitting hairs, while agreeing with what you wrote. My
point was only that, even below the transition altitude, with the altimeter
set to the QNH, there can still be differences between barometric
(indicated) altitude and true altitude. While these are occasionally
significant for terrain clearance, it's OK for separation as long as
everyone has the same reference pressure set.

Julian