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QFE/QNH for take off/ landing

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QFE/QNH for take off/ landing

Old 7th Feb 2022, 08:21
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Originally Posted by usedtobeATC View Post
When I was a RW controller in Moscow in 70s, some pilots (by mistake ) descent to aerodrome hight by QNH in QFE area. Most often they were pilots from the Middle East.
Interesting remark, do you remember the phraseology you used when passing the pressure? , did you say "Fox Echo 1020" or just : "Altimeter setting 1020 " and did you pass it in Millibars or in millimeters of mercury ?
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Old 7th Feb 2022, 10:43
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Thanks a lot for the info, , super photo ? I am sending you a PM .
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Old 7th Feb 2022, 11:05
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Originally Posted by usedtobeATC View Post
When I was a RW controller in Moscow in 70s, some pilots (by mistake ) descent to aerodrome hight by QNH in QFE area. Most often they were pilots from the Middle East.
Some RAF colleagues of mine had a big scare during a non precision helicopter approach to a German military airfield (early 1980s; might have been Buckeburg, not sure) when they came out cloud only just above trees on a ridge. They thought they were flying on QFE but had actually been given the QNH. Bearing in mind that this was forty years ago, I’m glad to say that due to the honesty of the crew and the publicity this was given at the time, I was lucky enough to have learned from someone else’s mistake rather than my own. Hopefully others did too. If in doubt, always cross check.
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Old 7th Feb 2022, 13:04
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Whatís QFE?

When I started gliding in my teens, you set the altimeter to zero on the ground, but as soon as I started flying cross-country, I changed to QNH all the time as the numbers printed on the map actually meant something then, in terms of airspace and terrain, and when talking with other pilots you had a common datum.

Iíve done a fair amount of airline ops using QFE where you had to, made a bit easier by a QFE option in the FMC as well as a metres one. Ditching QFE means one less pressure setting to forget out of QFE, QNH and QNE and there are lots of major airports that are high enough that many altimeters canít be set to QFE anyway.

If you do all your flying on QNH, you just get used to it. Ultimately, the solution is going to be geometric altitude which will remove pretty much all the disadvantages of pressure-based systems.
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Old 7th Feb 2022, 13:40
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there are lots of major airports that are high enough that many altimeters can’t be set to QFE anyway.
Never heard of that one . You care to elaborate ?
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Old 7th Feb 2022, 14:16
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For a conventional mechanical altimeter on which you adjust the datum by moving the sub scale, the most used standard says they should be adjustable ~950mb to ~1050mb, so anywhere between -1,000í and 2,000í pressure altitude. Electronic ones have a wider range, I believe from ~750mb to ~1050mb, which would still cause problems trying to set QFE over 8,000' airfield elevation, like Bogata and many other airports in South America and China.
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Old 7th Feb 2022, 19:50
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I think it's horses for courses really. I've operated both with different types of operation. If you've been brought up on QNH during initial training you don't think twice about the issue of calculating pattern altitude.
But then again the QFE/QNH debate is as old as aviation.
One thing I do know observing in the simulator is I've seen more bust missed approach heights/altitudes when the approach has been flown on QFE and QNH has not been set on the Go Around; this applies in particular with higher performance aircraft with a relatively low level off.
I was with one operator when we changed from QFE to QNH operation in the 1980s and thereafter I rarely saw a bust missed approach altitude on a Go Around.

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Old 7th Feb 2022, 20:19
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……….and didn’t we both work for an operator which used both at the same time !
I seem to remember the call “ qfe, qnh difference checked “ !
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Old 8th Feb 2022, 02:53
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For a conventional mechanical altimeter on which you adjust the datum by moving the sub scale, the most used standard says they should be adjustable ~950mb to ~1050mb
There have been times when the QNH exceeded both the upper and lower limits.
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Old 8th Feb 2022, 08:52
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I’m sure that when I started out some airline SOPs used QNH and others QFE and the RAF seemed to change their mind which to use every time they got a new OC pressure setting. In a radio-optional VFR world I always thought QNH gives you more - you’re always likely to be in the right ballpark area for terrain clearance and rejoin from the airfield overhead.
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Old 8th Feb 2022, 14:54
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Fireflybob +1. Iíd suggest it depends on the operation.

Iíd suggest QFE for circuits well away from controlled airspace. QNH if there is controlled airspace nearby or overhead. Iíd agree a potential threat with QNH for circuit work is the possibility of confusion in the event of an EFATO but that can be briefed as part of TEM.

Airline ops seem to work fine with QNH as MSA, terrain etc defined wrt altitude. As others have mentioned at a high altitude airport winding off QFE may be impractical if not impossible. Other areas like fast jet and rotary Iíve no experience so Iíll leave to others to comment.
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Old 8th Feb 2022, 20:30
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From a Met point of view [and I ceased being involved in 1997 so may be behind the curve]
The barometric pressure is to be read "frequently" when pressure is changing rapidly, and a "Special on QFE" issued to ATC against a signature or initials.

This was done scrupulously on RAF stations, with highly skilled and well-motivated observers who were often on watch solo. It was mandatory to keep a running log of pressure [hourly or half-hourly] and the observer was expected [of course] to be conversant with the overall Met. situation. We regarded monitoring of pressure as Holy writ, drummed into us on Day One..
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Old 10th Feb 2022, 08:08
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Originally Posted by ATC Watcher View Post
Never heard of that one . You care to elaborate ?
Some airport you do not even set QNH but QNE, yes not QFE.. QNE.. Have a read :-) Interesting ..
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Old 19th Mar 2022, 18:31
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……….and didn’t we both work for an operator which used both at the same time !
I seem to remember the call “ qfe, qnh difference checked “ !
Retired BA/BY yes that too!

Because the Kollsman (?) altimeter on the RH side referenced the pressurisation for landing until they retrofitted a standby altimeter which did that job and then a proper servo altimeter on the RH side - happy days!
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