[Fellsteruk]

Hey,

Sorry if a stupid question and i feel like i should know this given where i am with my training but im not sure and this is the best place to get an answer. So i know the difference between QFE and QNH, one is pressure at sea level the other airfield pressure the difference between them, 30ft for 1hpascal gives the height of the airfield...

However regardless of the airfield, do you always use QFE when landing, is it that simple?

The reason for this question, all of my basic training out of Liverpool, Im pretty sure all ive used is QHN, it's what i readback and set prior to take off and what was confirmed by Radar on re-joining and landing. QFE not mentioned.

Yet on a recent flight after a land away "only difference i can see", got clearance to rejoin, QNH confirmed then my instructor mentioned i hadn't set the QFE "i wasn't given it i got QNH" Asked the tower to confirm QFE which they did and I landed on that.

I understand why you would use QFE especially when your joining the circuit pattern you need to be at the same height right and I used it when landing away on this trip. But it's the first time, i'm sure, i've used QFE, previously always using QNH.

Please help clarify my confusion here?

Thanks

[AndyR]

As most circuits tend to be at 1000’ it can save doing sums to work out what the circuit height should be as an altitude rather than a height.

Liverpool is near as damn it at sea level, as are many coastal airfields of course, so it makes little difference (show me a pilot who can hold altitude to +/-30’, there aren’t many). It obviously makes a difference when an airfield is say 648’ asl. It helps to ensure that by using QFE all pilots are around about the same height as they fly the circuit if they set QFH and fly at the designated height according to the local procedures.

Needless to say QFE should only be used in the airfield vicinity. Though some military units will give you clearances to transit on their QFE, so you’ll need to be aware of the difference for terrain separation.

If you ever go on to fly commercially or instrument flying, you’ll find that QNH is the default.


Edit: I see Liverpool thresholds are 59 and 78 feet for 09 and 27, so guess your instructor has a point.

[Morten]

This is a hotly debated topic, along with the regional pressure setting... and this may become a long thread, even on the student forum. My thoughts are below, but other may disagree.

The benefit of the QFE is that it should read 0 when you have landed and hence any circuit height etc can be read of directly on the altimeter with QFE set on the subscale. So what's not to like?

Fiddling with (and remembering to do it at all) the altimeter setting as you approach the airfield adds a factor for error and, conversely, if you fly cross-country with QFE set you could be likely to infringe vertically unless your airfield is close to sea level. So any unnecessary altimeter change should be avoided and you should just fly with QNH set throughout.

Of course, that then requires a modicum of mental arithmetic to translate a 1,000 feet circuit to an altimeter reading of 1,810 feet at Compton Abbas, for instance. And that required mental agility can also give room for errors.
Finally, flying from airfields at high altitudes there are some QFEs you cannot set as the dial only goes that far...

It seems that QFE is only used in the UK and some people may therefore regard it as out of step and best forgotten.

But the truth is probably that you need to (i) do what your FI and examiner wants you to do - which is probably to switch between QNH for cross-country and QFE for circuits - and then (ii) once you start flying post-PPL, do whatever you think works best for you.

Personally, flying with QNH set and adding 1,000 (or 800) feet to the airfield elevation to get the circuit height gets my vote as I like to keep life simple with as few adjustments as necessary. Also, once I'm in the circuit I rarely look at the altimeter as I fly by sight and view of the runway, not by instrument.

[tcc1000]

At North Weald, most instructors use QNH and at least one uses QFE. A major concern there is Stansted class D at 1500ft (on their QNH), hence why QNH is preferred. I don't think using one over the other is wrong - but one may be better than the other depending on other conditions. I tend to watch the altimeter at circuit height so I don't go too high, but fly visually once I start the descent. Of course, if you have 2 altimeters, then setting them to QNH and QFE in the circuit sounds like a plan...

[Nero]

Of course, if you have 2 altimeters, then setting them to QNH and QFE in the circuit sounds like a plan...

This is what I do when returning to Biggin Hill. It's at 590ft approx and they always say the QFE when you ask for rejoin instructions.

So I always keep the lower altimeter at QNH and the top altimeter changes to QFE on rejoin.

~ Scott

[Iceman]

Be aware that an altimeter can be set to QFE only when the airfield is below a certain elevation and the pressure on the day allows. In the UK, this constraint rarely matters as the highest airport (licensed) is Dunkeswell in Devon (elevation 839 ft) and extreme air temperatures rarely cause a problem. If you went to the US though, there is no such altimeter setting as QFE, and as the transition altitude is 18000 ft, most private pilots never get the opportunity to use flight levels either. They have one ‘altimeter setting’ which is the equivalent of our QNH, and they measure air pressure in inches of mercury rather than hectoPascals. It is not uncommon in parts of the US to have airfield elevations in excess of 7000 ft, whereupon it is simply impossible to set an altimeter to a setting equivalent to QFE. Hence, all flying in the US, irrespective of airfield elevation, including takeoff, landing and circuits is done on the equivalent of QNH. Hence, when you takeoff and land, the altimeter should always read the airfield elevation. Flying from somewhere like Liverpool airport in the UK, ATC are always present and a QFE is always available. However, if you go to any unmanned airstrip in the UK or land after ATC have gone home at places like Blackbushe then there’s nobody around to give you a QFE so you will then have to land on QNH typically, your circuit altitude then being adjusted for airfield elevation. Something to bare in mind is to have the flexibility to be able to use either QFE or QNH, even when in the UK.

Iceman

[Fellsteruk]

Thanks chaps, much appreciated you sharing your views.

[Rob P]

I operate from a glider field which on non-gliding days has nobody around to give you a QFE.

I suppose I could fly the circuit at 1185 feet, but I'm happy just to wind off a little bit under 200 ft as part of my pre-landing checks.

Rob P

[Kittyhawk]

However, if you go to any unmanned airstrip in the UK or land after ATC have gone home at places like Blackbushe then there’s nobody around to give you a QFE so you will then have to land on QNH typically, your circuit altitude then being adjusted for airfield elevation. Something to bare in mind is to have the flexibility to be able to use either QFE or QNH, even when in the UK.

Iceman

I fly from an unmanned strip, so just wind the field elevation off the altimeter on initial approach, as Rob P says. Similarly, there is no one to give you a QNH prior to departure, I just set field elevation to get it.

[Iceman]

Yes, you are using your previously obtained QNH as your reference datum in order to ‘calculate’ your QFE.

Iceman

[skydriller]

QFE is a very British thing, you need to know about it for your PPL, and if your instructor wants you to use it then you should...

...However...Outside the UK you wont be given it and this is because at many aerodromes you wont be able to wind the altimeter far enough to set a QFE because they are too high an altitude. Altimeter setting errors have also caused Airspace Infringements, which is a hot topic in the UK, and QNH/QFE difference is part of this.

This is why many pilots no longer use QFE and only ever use QNH (or Flight Levels/1013mb) once they have their PPL and start flying places.

Regards, SD..

[mikehallam]

QFE is only right for one spot on the ground, whereas QNH gives your height over that whole region.
As l like to miss hitting obstacles, masts, hills etc. including ATZ's the latter is always right !
lt will still show a number equivalent to the field height published when on the deck.
Lots of fields radio give out QFE, which l acknowledge but ignore, preferring to keep a keen watch outside for circuit traffic, not head down fiddling the altimeter, especially as l am bound to forget to reset after take off and need to get an ATIS to restore QNH.
Like the man said, do what your instructor wants till you have a PPL, then make your own decisions !

[FlightDek]

I also fly from Liverpool. As the clearances within the CTR are given as altitudes it makes sense to use QNH. If I'm landing somewhere with no CAS to worry about I'll use QFE

When departing somewhere I'll always set QNH. I forgot once and nearly infringed approaching Liverpool

[flybymike]

Don’t forget, reporting of “height” and location is required when entering and leaving an ATZ so CAA presumably prefers QFE to be used inside the ATZ if a re-education course is to be avoided.
Or perhaps the whole rule 11 shenanigans is just bonkers.....

[tcc1000]

But surely in practice if you are asked for "height" you can always reply with altitude as long as you state that. Norwich class D, for example, asks to "report level" to which I would reply with something like "altitude 2000ft on 1007". Arguably if they have already given you the QNH then either "altitude 2000ft" or "2000ft on 1007" is sufficient.