Primarily for general aviation discussion, but other aviation topics are also welcome.
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When doing circuits, what height setting do you use on your altimeter?

QFE
130
65%
QNH
67
33%
RPS
No votes
0%
I don't look at the altimeter anyway
4
2%
#1518939
mick w wrote:"
What's the easiest & most accurate way we can all guarantee to be at the same level ??. :wink:


Waterski as close as possible to the nearest beach while setting altimeter to zero, QNH. Shimples! :clown:
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By Alastair
#1518981
malcolmfrost wrote:
the altimeter in the control tower”

Talkdownman wrote:
...which may not have been checked or calibrated since it was last removed from an aircraft, or dropped on the floor. Some 'tower' altimeters happen to be in those 'towers' because they are no longer fit for service in an aircraft.


The requirements of CAP746 are that
All pressure sensors that are used at an aerodrome as primary or as contingency devices are required to be calibrated on an annual basis.
The Met Office check calibration records when they conduct annual or bi-annual visits to ATC or FISO units therefore 'tower' altimeters cannot be there because "they are no longer fit for service in an aircraft", though it could be the case for Air/Ground units.
By Joe Dell
#1518982
Referring to the OP. Why would I want to go down the airfield (UK) and fly circuits on anything other than QFE?
Can anyone give me one good reason not to? Where's the advantage in sitting on the ground and winding my altimeter up from zero to airfield elevation?
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By fattony
#1518998
Joe Dell wrote:PS. You wouldn't be adjusting your altitude on the downwind leg. HEIGHT :naughty:

Surely if you fly "downhill" on the downwind leg in order to maintain 800ft AGL, you're ONLY adjusting your altitude - your height remains the same (800ft AGL)?
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By Crash one
#1519003
Joe Dell wrote:Referring to the OP. Why would I want to go down the airfield (UK) and fly circuits on anything other than QFE?
Can anyone give me one good reason not to? Where's the advantage in sitting on the ground and winding my altimeter up from zero to airfield elevation?


As I said earlier.
There is always the chance of some plonker flying through the zone reporting alt on QNH as "2000ft overhead" while you are reporting 1000ft downwind. Elevation 1000ft. (Other sets of numbers are available)
#1519008
I prefer Qfe as next door Shawbury use Qfe for their MATZ
If they are closed and you have Qnh of a nearby airfield you can wind off field elevation with no problem. Generally do not use regional pressure setting for cruse as it will not keep you under controlled airspace.
#1519010
Joe Dell wrote:Referring to the OP. Why would I want to go down the airfield (UK) and fly circuits on anything other than QFE?
Can anyone give me one good reason not to? Where's the advantage in sitting on the ground and winding my altimeter up from zero to airfield elevation?


- Flying using the QNH allows you to gross error check the function of your altimeter before you get going;
- Flying using the QNH gives you relevant information in relation to obstacles, terrain and airspace around you;
- Flying using the QNH equips you with the correct information when you are flying to other airfields and avoids the need to change altimeter settings unnecessarily - you just read the circuit altitude from the plate;
- Flying using the QNH prepares you to fly to/from airfields which are higher than the sub scale lets you wind off;
- Flying using the QNH prepares you to fly abroad and to airfields where a QFE may not be available (either by convention or because there is nobody who can give you the QFE over the radio);
- Flying using the QNH prepares you for the day that you decide to continue your training and development and either go and fly on instruments in IMC or strip flying where the QNH is a lot more useful to have than a QFE from an airfield you are not going back to;
- Flying using the QNH makes you more weather aware.

Other than that I can not see any advantage of using the QNH over the QFE.

:twisted:
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By Dave_Ett
#1519033
When will we all stop using pressure as an altitude / height reference, and switch to using GPS based? Seems to me that would get rid of all the issues with a variable medium.
We still need speed referenced to the air surrounding the wing of course, but so far as I can see we only need vertical information to stop us flying into each other and the ground, and neither of those relies on the atmosphere as a reference?
By chevvron
#1519041
Dave_Ett wrote:When will we all stop using pressure as an altitude / height reference, and switch to using GPS based? Seems to me that would get rid of all the issues with a variable medium.
We still need speed referenced to the air surrounding the wing of course, but so far as I can see we only need vertical information to stop us flying into each other and the ground, and neither of those relies on the atmosphere as a reference?

Not all aircraft are equipped with GPS.
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By kanga
#1519044
.. and it relies on external signals and internal power, either of which could fail at any time. If barometric altimeter is working at start of flight, set to whatever subscale value pilot chooses to use, there is a pretty good chance it will keep working adequately throughout any sort of flight which I would undertake. :)
#1519050
Isn't it the case that (without a augmentation such as DGPS), the precision available from a typical aircraft altimeter is quite a bit better than that from GPS altitude?

Consequently, even if the reliability was suitably high (which it isn't, really, as kanga says) GPS still wouldn't be as good as the traditional method.
T67M liked this
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