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%
User avatar
By flyingeeza
#1518815
flybymike wrote:
flyingeeza wrote:
Joe Dell wrote:Bagby airfield (circuits 800ft QFE) ....bla bla bla... and please join the circuit at 800ft. (QFE).

That actually means that the circuit is 800 feet above field elevation, and nothing more.
What I do with my altimeter is my business.


Bagby runway is on a significant slope. Just make sure you fly downhill on the downwind leg for 06 in order to maintain 800feet agl.

At which end is the QFE value taken, and how do you judge a "downhill" slope maintaining 800 feet agl?
Do you have to constantly watch the altimeter and adjust your altitude as you go along the downwind leg?
#1518821
Rob P wrote:I still don't understand why this matters so much to a few people. Use one, use the other. Who cares? Not me.

Rob P

To me it's interesting to see how many other pilots prefer not to use QFE, despite it being part of the UK training regimes. So it's comforting to know it's not just me who thinks it's a waste of vital lookout time when inbound to the most likely place for a conflict...the circuit.
Flyin'Dutch' liked this
#1518826
flyingeeza wrote:At which end is the QFE value taken, and how do you judge a "downhill" slope maintaining 800 feet agl?
Do you have to constantly watch the altimeter and adjust your altitude as you go along the downwind leg?


It's taken from close to the midpoint. So accurate to +/- 40ft. Close enough for most folk. There is a notice in the tower which says add or subtract one Mb depending on which direction is in use. In practice it makes little difference.

I habitually check the Tower altimeter against Topcliffe's , with a crosscheck against taxying aircraft's QFE if I can. No gross errors to date. :)

PS. You wouldn't be adjusting your altitude on the downwind leg. HEIGHT :naughty:
flyingeeza liked this
#1518828
A circuit is a visual maneuver. Once you've left circuit height/altitude, the only instrument you should be using is the ASI.
IMHO the circuit height/altitude is chosen for noise reasons and to keep circuits tight. You could say fly 1500 feet on the Heathrow QNH and it doesn't matter as long as everyone's on the same pressure setting.
#1518842
malcolmfrost wrote:it doesn't matter as long as everyone's on the same pressure setting.


That's the key issue, but I would expand it. The objective should be that airport operations anywhere, any airport, any country should be conducted with minimal variation in procedure, and altimeter settings should require as little communication as possible. Ideally ATIS, ASOS or similar should supply the the altimeter setting with no need for ATC or equivalent to supply it for VFR aircraft. If there is terrain near the circuit (my base has a 1600 ft high hill within the circuit) the charted altitude of the hill should match the altitude on the altimeter. Same for airspace delineations. If the runway is at high altitude, that should be unimportant. If ATC has radar (either at the airport or approaching the airport, and regardless of which ATC any given plane is talking with) and is it using it to advise multiple pilots of other traffic there should be no need for ATC to consider altimeter settings in use by different aircraft or different ATC facilities in the same area. If two pilots/aircraft are coordinating their separation on an air-to-air frequency they should not have to discuss altimeter settings. Everybody in the entire area, whether operating at the airport, passing over the airport or anywhere near should be on a altimeter setting that matches every other aircraft and every charted geographic or airspace feature in the area.
Last edited by Silvaire on Sun Feb 12, 2017 4:58 pm, edited 2 times in total.
Derryn liked this
#1518846
flyingeeza wrote:
flybymike wrote:
flyingeeza wrote:That actually means that the circuit is 800 feet above field elevation, and nothing more.
What I do with my altimeter is my business.


Bagby runway is on a significant slope. Just make sure you fly downhill on the downwind leg for 06 in order to maintain 800feet agl.

At which end is the QFE value taken, and how do you judge a "downhill" slope maintaining 800 feet agl?
Do you have to constantly watch the altimeter and adjust your altitude as you go along the downwind leg?

Where the threshold elevation is more 7ft or more different from the aerodrome elevation, you should be using 'QFE Threshold', bearing in mind 'aerodrome elevation' is taken from the 'highest point on the landing area' not from the aerodrome reference point.
flyingeeza liked this
#1518852
One other aspect - if you're flying from a field with nobody on the ground to give you a QFE, or a QNH, you're on your own. The technique is to set airfield elevation on the altimeter when you are about to take off, which will give you an "as near as dammit" QNH. Similarly fly inbound on the last known QNH and fly the circuit height plus airfield height. Keeping a lookout for aircraft on slightly different QNHs.

Much better if we'd never heard of QFE and did alt calculations automatically.
User avatar
By flybymike
FLYER Club Member  FLYER Club Member
#1518854
Where the threshold elevation is more 7ft or more different from the aerodrome elevation


The "Tower" at Bagby is a good 6 feet agl, but it's ok cos Joe Dell knocks a fifth of a millibar off the QFE to compensate.
#1518863
flybymike wrote:
Where the threshold elevation is more 7ft or more different from the aerodrome elevation


The "Tower" at Bagby is a good 6 feet agl, but it's ok cos Joe Dell knocks a fifth of a millibar off the QFE to compensate.

:lol:
Much like flying at 1495 feet under 1500 foot CAS bottoms...some fine QNH tweaking going on there! :D
User avatar
By mick w
FLYER Club Member  FLYER Club Member
#1518930
" Keeping a lookout for aircraft on slightly different QNHs. " .

And there you have it in a Nutshell !!.

Question For Everyone ?.

What's the easiest & most accurate way we can all guarantee to be at the same level ??. :wink:
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