Quote:
Originally Posted by IvanK
I think you will find the Brits to use QFE as a general rule.
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It very much depends what we're doing.
Gliding, I'll just zero the altimeter as part of the pre-flight checks. This isn't necessarily going to be the same as QFE because QFE is updated in discrete intervals along with the ATIS (though one generally doesn't fly gliders from somewhere which has an ATIS).
But looking at it another way, if you set QFE in a powered aeroplane, you won't necessarily find the altimeter set exactly to zero when you're sat on the tarmac, because real objective of the exercise is to make sure that everybody is at the same height in the circuit so that they can all see each other, and nobody descends onto anybody else's head. Assuming about 30'/mb, and a rate of pressure change of about 1 mb/hour, you might get a 30' error relative to the ground, which is quite acceptable for visual flying. But this means that QFE isn't the same as simply zeroing your altimeter on the ground.
Powered, I'd be inclined to use QFE for flying in the circuit, but otherwise, it makes pretty good sense to use QNH, not least because the regional pressure setting is a QNH.
In the end, this is just a function of the fact that the maps are made by reference to mean sea level as a datum line, because it's effectively universal.
Earlier today I was flying aerobatics in a Bulldog with the altimeter set to QNH for the entire sortie from engine start to engine stop. The obvious advantage is that you don't have to worry about making a mistake when switching between QNH and QFE or vice versa.