by RollerBall » Sun Dec 04, 2005 6:15 pm
In the UK, when you approach an airfield to land, ATC gives you the QFE which is the altimeter pressure setting corrected for airfield elevation. This is almost always different from the QNH (as most airfields aren't at sea level) or the Regional setting (in real life you don't have every single little airfield you fly over giving you a different altimeter pressure setting - that would just not be safe - you get a setting covering a large area or region that each en-route radio service will give to aircraft in that region so they can all fly at known safe separations).
When you are approaching to land the QNH or Regional are pretty useless. You want to know the QFE so you get a direct reading of your true altitude with reference to the airfield elevation so you can join with other traffic and fly an accurate, safe circuit at the designated height. This can vary from typically 800ft for smaller airfields to 1000ft or higher, so it is important and you would take the trouble to find out what the joining procedure is, by telephone if necessary, or from Pooley's or Air Pilot before taking off. And it's not a difficult setting to determine - it's just a straight reading from a barometer up on the Tower wall if you will.
Not having flown en route in the US I don't know what the official procedure is but if as in the sim, all you get when approaching to land is QNH, that's pretty useless compared to what happens in Europe. Maybe one of our US real life pilots can enlighten us and explain if they really do use such a system which unnecessarily adds to pilot workload at a time when workload can already be at a pretty high level.
Last edited by RollerBall on Sun Dec 04, 2005 6:17 pm, edited 1 time in total.