Private Flying LAA/BMAA/BGA/BPA The sheer pleasure of flight.

QNH or QFE ?

Old 2nd Aug 2018, 16:40
  #21 (permalink)  
 
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I flew some second hand AA 727s. Their altimeters had an expanded range for the Kollsmam window. It's all what you're willing to pay.
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Old 2nd Aug 2018, 17:02
  #22 (permalink)  
 
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When I left the RAF, all maritime and transport aircraft were using QNH and not as someone else suggested QFE. Quite what they do in basic training and fast jet ops these days I will let others guide you.
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Old 6th Aug 2018, 11:00
  #23 (permalink)  
 
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Just to put some non UK pilots into the picture of our situation. In the UK most airfields are below 250 ft asl, so it is very easy to set QFE. Whilst in the circuit, it is much easier to fly with the altimeter reading 1000ft, than to have to remember it's 1190 qnh for Carlisle, 1081 qnh for Liverpool, etc etc.
Also for those few odd airfields that have circuit heights of 800 ft or 1500 ft it is so much easier to fly QFE than have to do the maths, especially when you are trying to nail the turn onto final at 600 ft aal.
.
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Old 6th Aug 2018, 11:48
  #24 (permalink)  
 
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Originally Posted by scifi View Post
Just to put some non UK pilots into the picture of our situation. In the UK most airfields are below 250 ft asl, so it is very easy to set QFE. Whilst in the circuit, it is much easier to fly with the altimeter reading 1000ft, than to have to remember it's 1190 qnh for Carlisle, 1081 qnh for Liverpool, etc etc.
Also for those few odd airfields that have circuit heights of 800 ft or 1500 ft it is so much easier to fly QFE than have to do the maths, especially when you are trying to nail the turn onto final at 600 ft aal.
.
Denham circuit height 750 ft elevation 249ft.
And the 'official' pressure setting to be used in the UK is QNH, with QFE made available on request.
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Old 6th Aug 2018, 11:50
  #25 (permalink)  
 
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Originally Posted by scifi View Post
Just to put some non UK pilots into the picture of our situation. In the UK most airfields are below 250 ft asl, so it is very easy to set QFE. Whilst in the circuit, it is much easier to fly with the altimeter reading 1000ft, than to have to remember it's 1190 qnh for Carlisle, 1081 qnh for Liverpool, etc etc.
Also for those few odd airfields that have circuit heights of 800 ft or 1500 ft it is so much easier to fly QFE than have to do the maths, especially when you are trying to nail the turn onto final at 600 ft aal.
For Carlisle fly 1200 ft QNH, for Liverpool fly 1100 ft. Experienced pilots will judge their turn onto final visually rather than by reference to the altimeter. It's a useful skill to have for when the circuit has to be non-standard shaped for any reason.
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Old 6th Aug 2018, 11:57
  #26 (permalink)  
 
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At Redhill ATC will instruct to "join overhead at 1,400 QNH" or "descend to 1,200 ft and join right base". Airfield elevation is 222 ft.

Simple
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Old 6th Aug 2018, 22:07
  #27 (permalink)  
 
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Denham circuit height 750 ft elevation 249ft.
I learned to fly at Denham in the early 80's. We did everything on the QNH, which made the circuit altitude 1,000', very easy. The local flying area is only up to 1,000' QNH, above that you're inside the Heathrow zone, used to be Class A!
Then I went elsewhere and learned that it was easier to 'go with the flow' and use QFE 'cos that's what everyone else was doing.
Later on, I did my instructor course also at Denham and went back to QNH for everything. My first instructor job was on the other side of the airfield, where they insisted we teach QFE! (Just to spite the opposition over the other side, I suspect).
Now I teach aspiring airline pilots all-QNH but go along with old-timer PPLs in our Club who want to use QFE - just so long as we know what we're doing, that's what matters to me.
TOO
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Old 7th Aug 2018, 10:06
  #28 (permalink)  
 
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Originally Posted by Discorde View Post
Here's a thread which started almost 10 years ago:

QFE who needs it?
Link doesn't work for me but I'm not using Windows.
10 years ago was about the time the CAA designated QNH as the 'official' pressure setting.
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Old 8th Aug 2018, 09:20
  #29 (permalink)  
 
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Originally Posted by chevvron View Post
Link doesn't work for me but I'm not using Windows.
10 years ago was about the time the CAA designated QNH as the 'official' pressure setting.
This was the original post of that thread:

I am convinced that GA altimeter setting procedures in the UK are far too complicated. Do we really need Regional Settings? Do we really need QFE? The VFR pilot flying in Class G airspace has to reset his or her altimeter several times. Two problems arise: firstly, there is always a chance of setting an incorrect subscale setting every time it is adjusted and secondly, distraction during resetting can draw the pilotís attention away from other vital tasks, such as lookout and navigational monitoring.

A simpler procedure would be to set local QNH for the whole flight, resetting only if the QNH changes. Rarely does barometric pressure change rapidly, so even if the subscale was not reset at all during the flight the resulting altimeter error would be unlikely to exceed 100 feet or so. Is this significant for VFR flight?

Two further advantages of 'local QNH' flight are improving terrain awareness (which QFE degrades) and reducing the potential for violation of controlled airspace, which in the lower levels usually has a base expressed as an altitude. For student pilots doing circuit work, patterns flown with QNH set would not be difficult to learn. When they came to land away from base, adding field elevation to pattern heights to determine pattern altitude would be part of their pre-flight preparations and could be recorded on the nav log. If a MATZ controller specifies a QFE-based penetration height it is easy to convert this to a QNH-based altitude, rounding up or down to the nearest 100ft.

Finally, it should be noted that commercial airliners around the world fly local QNH below transition altitude and 1013 above it. If it works for the big boys and girls, why not for GA traffic too?
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Old 8th Aug 2018, 10:44
  #30 (permalink)  
 
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Originally Posted by Discorde View Post
A simpler procedure would be to set local QNH for the whole flight, resetting only if the QNH changes. Rarely does barometric pressure change rapidly, so even if the subscale was not reset at all during the flight the resulting altimeter error would be unlikely to exceed 100 feet or so. Is this significant for VFR flight?
I think that's what the CAA want you to do but because of some diehard civil pilots plus the RAF who insist on using QFE, we're stuck with the present system.
Like TheOddOne, I got into the habit of using QNH only when flying from Denham.
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Old 8th Aug 2018, 10:47
  #31 (permalink)  
 
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Discorde: I don't think you are going to make much progress on this issue until the "Luddite" flying clubs stop teaching QFE procedures!
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Old 8th Aug 2018, 17:15
  #32 (permalink)  
 
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@Discorde: thanks for the copy!

Regarding
A simpler procedure would be to set local QNH for the whole flight, resetting only if the QNH changes
: yes, if "local" QNH were universally available. But it isn't always. So I am afraid "regional QNH" is the least unfortunate that can be done. And it works reasonably well, in reasonably flat areas. As for discarding QFE: yes of course. Those funny Brits are alone to want QFE, anyway; and not even all of them.
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Old 8th Aug 2018, 17:22
  #33 (permalink)  
 
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Originally Posted by Jan Olieslagers View Post
@Discorde: thanks for the copy!

Regarding : yes, if "local" QNH were universally available. But it isn't always. So I am afraid "regional QNH" is the least unfortunate that can be done. And it works reasonably well, in reasonably flat areas. As for discarding QFE: yes of course. Those funny Brits are alone to want QFE, anyway; and not even all of them.
There's no such thing as 'Regional QNH' in the UK, but there might be in other countries.
I understand QFE is still used in Russia, China and Mauritius.
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Old 8th Aug 2018, 17:36
  #34 (permalink)  
 
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There does be "regional QNH" in ICAO definitions. I even know of a few places where it is actually used. But far from me to advocate the concept, I'll not go beyond calling it "the least unfortunate compromise".

And I will agree the UK is not the only third world country to cling to the past.
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Old 8th Aug 2018, 19:56
  #35 (permalink)  
 
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"There's no such thing as 'Regional QNH' in the UK, but there might be in other countries."
When did Altimeter Settings such as "Orkney 992 hectopascals, Portree 997 hectopascals" stop being used in the UK?
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Old 8th Aug 2018, 21:12
  #36 (permalink)  
 
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If you don't like QFE then don't use it. Why try and stop others from using it if they so choose?

I use QFE wherever possible but I don't complain about you using QNH? Why does it annoy you so much?

Leave little QFE alone.

Mr Vice.
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Old 8th Aug 2018, 21:37
  #37 (permalink)  
 
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Originally Posted by Maoraigh1
When did Altimeter Settings such as "Orkney 992 hectopascals, Portree 997 hectopascals" stop being used in the UK?
I suspect chevvron may be alluding to the fact that it is correctly called the Regional Pressure Setting.

I'm all for getting something technical correct where it matters, but pedantry for the sake of it does become a wee bit wearing!
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Old 9th Aug 2018, 04:45
  #38 (permalink)  
 
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Originally Posted by LookingForAJob View Post
I suspect chevvron may be alluding to the fact that it is correctly called the Regional Pressure Setting.

I'm all for getting something technical correct where it matters, but pedantry for the sake of it does become a wee bit wearing!
Yes I was.
RPS is totally different from a QNH in that it's the lowest FORECAST pressure setting in a particular region rather than an actual measured and reported pressure setting at an airfield or other defined point.
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Old 9th Aug 2018, 08:04
  #39 (permalink)  
 
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And useless for most pilots as a result.
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Old 9th Aug 2018, 08:52
  #40 (permalink)  
 
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Originally Posted by chevvron View Post
Yes I was.
So why not say what you meant, rather than being obscure?

If you've got a point to make, it's helpful to educate people by making it rather than demonstrating some kind of perceived self-superiority.
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