Having read a number of forum members getting quite aerated about their favoured altimeter setting, I'm anxious to stay well out of that argument.
However, I'm trying to find a reliable formula to convert a QNH to the QFE for an aerodrome for which I know the elevation. I figured that:
QFE = QNH - (Elevation [in feet] / 3.2808399 [to convert to metres] * 0.12 [approx pressure reduction per metre at low level])
should be pretty good, but when I tried it for EGBJ (ARP elevation 101 feet) it gave me a QFE that was 4hPa (or millibars if you'd rather) lower than the QNH. Regular readers will know well that the QFE is normally given as
3hPa different. "No big deal", I hear you say - but whilst I can't fly with a level of accuracy that would make it a problem, I'd like to understand the difference. Is it that the threshold of the oft-used runways is really 6 feet lower than the ARP, or is there something important being left out of the formula? I read up a little bit about QFF, but it made my head go funny.
Your insights will be gratefully appreciated. Those wishing to debate the
merits of QFE should (respectfully) look elsewhere*.
Cheers,
Z
*I'm told the expression these days is "jog on".
