Airfield QNH - what's the point?

[Humaround]

Why do Airfields not use the QNH of the surrounding Region?

If I'm inbound, the airfield's QFE is useful. If we didn't use QFE as per the US, then airfield QNH would be useful as an alternative. But I can't see any reason to have both.

If I'm flying past and getting a basic service, I have to conform to the airfield QNH for a few miles and then change back to the Region.

Obviously all aircraft in the area need to be using the same QNH, but why have a different one to the surrounding area?

I'm sure there must be a good reason, but I'm blowed if I know what it is.

[S-Works]

Then perhaps a little more study of altimeter setting procedures is required.

Personally I never use QFE.

[RTN11]

IFR traffic only uses QHN with a good knowledge of airfield elevation and MSA, however a visual circuit will likely be based on QFE.

If anything they could do away with QFE and then visual traffic would have to be more aware of airfield elevation.

Regional QNH is something completely different again. An airfield QNH is based on the pressure MEASURED at that airfield, and will be very accurate so when you touch down you will have airfield elevation indicated. Regional QNH is the lowest FORECAST pressure for a region, giving a worst case terrain clearance based on altitude.

[Whopity]

By definition QNH is the pressure determined at a specific Point. A forecast Regional Pressure is based upon an estimate of the worst case (lowest) pressure and is known as the Regional Pressure Setting (RPS) it is not a QNH.

[Genghis the Engineer]

QNH is normally used for terrain avoidance, airspace avoidance, airfield procedures, and so-on within 25nm of the airfield in question.

RPS is for long routes where changing setting constantly isn't useful, and is the best case for a cluster of QNHs. It is conservative for terrain avoidance, but non-conservative for airspace, and potentially incorrect for flying an instrument approach procedure.

I use QFE, for preference, when flying visually in the circuit, but not for an IAP or terrain avoidance.

So, typical good practice is QNH on departure, RPS en-route (with a bit of fat to ensure you don't foul up and climb into the bottom edge of any airspace), then depending upon preference and procedure, QFE or QNH on arrival.

Not many countries use QFE, but it's useful and convenient in the UK.

G

[fujii]

with a bit of fat to ensure you don't foul up

Joking surely. With the tolerances some VFR pilots fly to "a bit of fat" reduces the safety margin between you and another aircraft with the correct QNH.

[sevenstrokeroll]

QFE...useless

QNH...why not use the closest properly reported altimeter setting to enhance accuracy?

Gee, how lazy are you...having to reach all the way up from the side of your body to reach the altimeter and actually move a knob.

[ShyTorque]

These days I tend to set the nearest airfield QNH because it's more accurate than the RPS, which is by definition subject to inaccuracy.

The QNH can be obtained via the ATIS or ATC if speaking to them).

[Pace]

I'm sure there must be a good reason, but I'm blowed if I know what it is.

Humaround

There is no good reason to Keep QFE going there are good reasons to get rid of it.
Often aviation is steeped in tradition on the principal of this is how its always been done.
The overhead join another example from the past when aircraft had no radio, needed to see the airport details, needed to make sure they were over the right airfield etc.
I am against QFE because it adds another point of confusion. Flying IFR we use QNH only! Most of the world do not use QFE and there is a potential dangerous mistake in the making having two altimeter settings operating near the ground.

Pace

[Johnm]

QFE is an anachronism beloved of the military for reasons unknown, airfield QNH is the really useful item, RPS is a nuisance and could be eliminated in favour of using nearby major airport e.g London Birmingham Manchester Edinburgh

[DB6]

A lot of airfields do use QNH rather than QFE - have a listen to the ATIS of any large airfield or look at the METARs. It is more relevant when flying pilot-interpreted instrument approaches, where the procedures are always referenced to QNH.
QFE is used more by training/smaller/VFR airfields and is easier for students/PPLs to use as you can just fly a 1000ft circuit rather than 1345 ft (or whatever). QNH is normally given as well. The RAF also use QFE (or used to, not 100% sure now), as their procedures are generally much more ground-controlled i.e. PAR, and ground controllers/PAR screens naturally work with reference to the runway threshold.
Regional QNH on the other hand is fairly meaningless and I personally never use it, preferring to use (and teach) use of any airfield QNH within 25nm. If, however, I was using regional QNH I wouldn't bother setting airfield QNH when flying past on a basic service, only if I was entering the ATZ.

[Heston]

Ah the old "what is the use of QFE?" debate. What larks, Pip.

Of course its of no use whatsoever (except one see below) and we should all use QNH. But I confess I do like it when the altimeter reads circuit height in the circuit and zero on the ground, its kinda comforting.

By the way I thought RPS didn't exist beneath CAS like the London TMA?:=

One fun use for QFE - confusing your students to see if they understand how things like altimeter setting, terrain clearance, base of controlled airspace, and the effects of changes in pressure as you fly towards a depression, all work. Seriously, this is important stuff and if they can't grasp QFE and QNH then they need some more help in this area.:rolleyes:

H

[flyems]

Gee, how lazy are you...having to reach all the way up from the side of your body to reach the altimeter and actually move a knob.

Could be interesting winding that little knob to set the QFE for Addis Ababa (HAAB) at 7,656' ASL...

[BillieBob]

Which is why we have QNE (which is not, of course, a pressure setting)

[GOLF_BRAVO_ZULU]

The assertion that QFE is an anachronism is a fair personal point of view. It remains, though, a point of view. Personally, I rather like QFE for my simple puddle jumping activities.

In the olden days, the early '70s, it was normal at Ringway aerodrome to pass the QFE and QNH. Perhaps rather quaintly, Speedbird and Beeline drivers used to set it for landing. Being vastly superior and advanced, Clipper ones didn't.

http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/icons/mpangel.gif

[Flyingmac]

Don't you get the airfield QNH by refering to the QFE?

[dont overfil]

More to the point what's the use of a RPS? When the area is too big.

The Portree ASR covers about 27000 square miles. Imagine the possible pressure gradient over that area.

D.O.

[JW411]

Personally, I think we should all use QFF.

[Humaround]

I had to look that one up.

"QFF is a Q code. It is the MSL pressure derived from the barometric pressure at the station location by calculating the weight of an imaginary air column, extending from the location to sea level, assuming the temperature and relative humidity at the location are the long term monthly mean, the temperature lapse rate is according to ISA and the relative humidity lapse rate is zero.
QFF is the location value plotted on surface synoptic chart and is closer to reality than QNH, though it is only indirectly used in aviation."

I'm inclined to agree that airfield QNH is more useful than QFE. The point of the post was to question the wisdom of aircraft in a small area using different QNH settings.

(I DO understand altimeter setting procedures, and I'm not too lazy to change the setting...)

[ShyTorque]

More to the point what's the use of a RPS? When the area is too big.

It was in common use many years ago so a crew could take off, fly in radio silence and still have a reasonably accurate (i.e. safe) altimeter setting to use en route. That is why you can get the hourly plus the next hour.

It's less of an issue now that radio comms are so much better and ATIS stations more widely available.

[vee-tail-1]

Hmnn... If like me, you only fly day VFR/VMC at flight levels over the UK, then only two pressure settings are needed. Standard 1013.2 & QFE (or A/F QNH if you like a bit more mental arithmetic) :)

[Whopity]

And very soon when the Transition Altitude is raised to 18000 feet you'll be flying on the QNH.

QFF is the location value plotted on surface synoptic chart and is closer to reality than QNH, though it is only indirectly used in aviation."QFF (next to QFE in the Q Code) was the forerunner to QNH, and was replaced because QNH is more accurate. CAP1 Q-Codes dated 1945 does not include QNH, which did not appear until a few years later.

[mm_flynn]

Hmnn... If like me, you only fly day VFR/VMC at flight levels over the UK, then only two pressure settings are needed. Standard 1013.2 & QFE (or A/F QNH if you like a bit more mental arithmetic) :)

You are very lucky to always fly in areas where there are no airways of other CAS defined as an altitude.

For most of my VMC non-airways flying I use the altimeter to ensure avoidance of airspace (as I can see the ground to avoid that and eye ball a landing pattern so the altimeter is more of a convenience than a necessity for these)

[Maoraigh1]

Flying from Inverness, they give me RPS on leaving. Lossie then tells me to use Lossie QFE. I Just use whatever keeps the guys i'm on radio contact with happy.

[CJ Driver]

Why do they still offer RPS? As was pointed out in an earlier post by ShyTorque, RPS was promulgated in the days of no-radio cross country flying, and is (by definition) NOT the correct altimeter setting for the region, but rather is guaranteed to be a lower number than the worst-case forecast for the period. It is intended to maintain terrain clearance when all other sources of altimeter setting have been lost. :uhoh:

If however you are flying near, or under, any airspace (such as the Scottish TMA) for which a proper QNH is available to you, then you must set that QNH, and not the RPS. Broadly speaking, a suitable QNH is always available to you providing your radio still works. In the last 30 years I have never had a total communications failure, and therefore have never needed to use the RPS (or had the pleasure of squawking 7600, come to think of it).

[Gertrude the Wombat]

Why do they still offer RPS?
I've not heard it used, or used it myself, for decades. Without checking I wouldn't have known it still existed.

(Edit to add: this is in south eastern England, where (a) it's flat and (b) there's an airfield every few miles.)

[dont overfil]

We need fisbangwallop to comment. Scottish Info regularly offer RPS probably because of the terrain north of the TMA.

The difference between the RPS and the Ed/Gla QNH can be huge.

Notams pop up regularly if there is low pressure, warning of the increased risk of infringement.

D.O.

[bookworm]

I'm inclined to agree that airfield QNH is more useful than QFE. The point of the post was to question the wisdom of aircraft in a small area using different QNH settings.

Why would this be an issue? If the aircraft are talking to the same ATSU who is offering them either a control service or an advisory service for separation, they will use the same QNH as given by that ATSU. If they're not, what hazard arises from the use of different QNHs?

[cotterpot]

I've not heard it used, or used it myself, for decades. Without checking I wouldn't have known it still existed.

(Edit to add: this is in south eastern England, where (a) it's flat and (b) there's an airfield every few miles.)

If you are flying by Wyton you get it as part of the basic service

[A and C]

Airfield QNH is essential for accurate IFR approaches down to CAT1.

QFE is used by the military mainly to recover fast jets by PAR and keep the pilot work load down.

QFE is prohibited in some airliners (B737NG) because it upsets the EGPWS.

Horses for courses really !

[Sideslipper]

Usually, whenever I depart from my local LARS provider they wish me farewell with "Squawk 7000, Regional QNH ****".
I take it as meaning "You are on your own now mate, and if you bump into something very solid it's your fault not our's".:)

[GeeWhizz]

I've not heard it used, or used it myself, for decades. Without checking I wouldn't have known it still existed.

Yep still used and constantly too. Given to any aircraft that isn't going to impact other inbound/outbound flights.

Flying from Inverness, they give me RPS on leaving. Lossie then tells me to use Lossie QFE. I Just use whatever keeps the guys i'm on radio contact with happy.

Giving an aircraft the RPS before leaving the frequency is a standard thing, but more importantly its the safest by nature of it being the lowest forecast QNH for the area. By crossing the path or flying overhead a aerodrome that primarily uses QFE for all its ops, its simpler for everyone to be flying a height on the same pressure (rather than mentally working out the separation). Of course if you need to use the QNH just ask for it, you will get a QNH and should get the airfield elevation too.

I take it as meaning "You are on your own now mate, and if you bump into something very solid it's your fault not our's".

Spot on! ;)

[mm_flynn]

Yep still used and constantly too. Given to any aircraft that isn't going to impact other inbound/outbound flights.

I suspect, until recently, RPS was used by the RAF for laughs when handing off poor GA aircraft to transit under the London TMA. ;)

Until a few years ago it was common with some military units to go from QNH to QFE for the transit then to RPS and a free call on route . . . a few miles before you then flew a couple of hundred feet below (or maybe above) the QNH define base of the TMA. I always assumed it was a plan to mess with the heads of PPLs and the TMA controllers.

[Sir George Cayley]

History & Nostalgia intrusion!

I was once told the reason why the Queen Nan How and Queen Fox Easy came about. They are, according to my source, mnemonics which equate to NH = Newquay Harbour and FE = Field Elevation.

I'd love to know if I was being fed a line or whether there is something in it.

SGC

[Aerials]

Sir George, I would expect it was Newlyn harbour, not Newquay because I believe it is the place that Mean Sea Level and tides is measured.

[flybymike]

I was always told "Field elevation" and "nautical height."

[Slopey]

I've not heard it used, or used it myself, for decades. Without checking I wouldn't have known it still existed.

Really? I get it leaving the Aberdeen Zone, from Scottish if in a different area, London if I'm down south, and at the arrival airport at least. VFR or IFR.

[sevenstrokeroll]

the "Q" codes are quite available...just google them

and for the ease of my students on the other side of the pond...

QFE... above field elevation
QNH...normal height

and QNE...normal enroute.

[vee-tail-1]

Hmnn ... I was taught that QNH = Altitude measured from Nil Height, or sea level.

[Thud105]

This thread perfectly captures UK GA's Rules & Regs. Everyone's got an opinion, and no one knows the answer!

[Crash one]

I can't see anything wrong with everyone using RPS, Terrain clearance, traffic separation, no twiddling knobs. Where would the problem be? Precision approaches in cloud/fog?

[dont overfil]

Crash one, if you fly under the Edinburgh TMA on RPS there's a good chance you'll bust their airspace.

D.O.

[airpolice]

Don't Overfill wrote:Crash one, if you fly under the Edinburgh TMA on RPS there's a good chance you'll bust their airspace.
I think he means the Scottish TMA.

[ShyTorque]

Where would the problem be? Precision approaches in cloud/fog?

Of course! If you're carrying out a precision approach, you need a precision altimeter setting that relates directly to the touchdown point. The RPS does definitely not fulfil that requirement because it's merely an average lowest setting for a large geographical area. It could be hundreds of feet out at any one location.

[BackPacker]

Slightly related to this. Where we fly aerobatics our lower level is usually 3000' on the QNH, and our upper limit is FL55. In other words we are always going up and down through the transition layer.

Obviously we're not going to reset the altimeter from QNH to 1013.2 and back every time we do a loop. Instead, we simply leave the altimeter on the QNH, and use the transponder to read the FL. Any Mode-C or Mode-S transponder will display that, and the transponder output will always be relative to 1013.2.

So if you're beneath some airspace that has its lower level defined as a FL, but you are using QNH or QFE for obstacle clearance/collision avoidance, you can use the same trick. Keep track of the altimeter and the transponder, and as long as both show you to be outside CAS, you're fine.

Now my question. Does anybody have an easy-to-use map of transition altitudes in the UK? I have looked at the AIP and all it says is that the TA is 3000' in general, but 6000' in/underneath a whole (textual) list of CTRs/CTAs/TMAs. But I could not find an easy-to-use map with TAs in the AIP.

[Dave Gittins]

I fly from Redhill, the threshold elevations are 149 feet. We fly circuits 1000 ft (ish) AAL at 1200 ft Redhill QNH. We have a 1500 ft "shelf" beneath the Gatwick Zone to fly under so use 1400 ft QNH.

If I move to Farnborough after departure, I cannot remember their QNH ever being more than 1 Mb different to Redhill.

It all seems pretty simple and straightforward to me .... any action you relate to feet above aerodrome, just add 200 ft, (that's if you really need an altimeter to tell you when to retact take-off flap on the climb or cancel carb heat on finals.)

When I fly in the USA (KFLY elevation 6874) the knob doesn't screw far enough to use QFE. Indeed it isn't even refered to anything other than "altimeter".

[chevvron]

Apart from airfelds situated under TMAs, the RAF tend not to use 'real' QNH. Many years ago, they tried changing to it; all MOD airfields had their procedures redesigned as QNH approaches; all MOD airfields had a presentation on the new procedures, and they were brought in. Then with little fanfare, they were changed back to QFE procedures!
Rumour had it that a senior RAF officer had not heard of QNH procedures and had set the pressure setting given to him thinking it was QFE, thereby nearly having a 'nasty', and he was senior enough to rule that QNH procedures were 'dangerous' and require a return to QFE procedures.
How true this is I don't know, but the result was the RAF initially at least, started using just QFE, SPS and RPS. Departure would be on QFE, changing to SPS at transition altitude (yes they did use that) or if remaining low level, changing to RPS outside the MATZ.

[soaringhigh650]

Rumour had it that a senior RAF officer had not heard of QNH procedures


So he's never ever landed overseas then... except when war has been declared...

[Crash one]

Crash one, if you fly under the Edinburgh TMA on RPS there's a good chance you'll bust their airspace.

D.O.


I thought that would stir the **** a bit.
Anyway, apart from using QFE or airfield QNH for a precision approach, if everyone in the region was on RPS?

[A and C]

I can assure those who think that the RAF had never been told about QNH approaches that is not the case, in fact they a few years back changed to QNH approaches, however this did not best meet the operational requirements of recovering fast jets in bad weather usually using PAR.

So the RAF switched back to QFE, if you operate into an RAF airfield in an aircraft that can't use QFE they are quite able to adapt the system to enable you to fly the approach using QNH.

[Contacttower]

Well the US Air Force seem to manage fine without QFE...

[mm_flynn]

Well the US Air Force seem to manage fine without QFE...

That will be because as students at the academy they can't be asked to wind 6500 feet on and off the altimeter every time they make an approach.

[fireflybob]

The QFE/QNH debate has been around as long as aviation has existed!

To me QNH is more logical - have the altimeter set to something you can relate it too, such as elevations of topo features (yes I know IAPs show height AAL too but am thinking more topo charts and even grid MORA on instrument area charts).

If you've been brought up on QFE and never done anything different the idea of flying on QNH seems quite alien - I was chief trainer for a Company when we changed from QFE to QNH operation - we put everyone in the simulator for a couple of hours and the switch was a non event. Having spent many an hour in the back of the sim I can tell you that there are far more altitude busts using QFE than there are with QNH.

As for the RPS - it's a throw back to the days of non radio aircraft and you needed a safe altimeter setting to fly (say) from London to Prestwick so the MET office would give you the lowest forecast QNH for the route - later on they introduces Altimeter Setting Regions (eg Barnsley)to enhance the process.

If I had anything to do with it I'd bin RPS completely (I await the flames now LOL) and also QFE - let's have aerodrome QNH as standard.

As a footnote in the USA they don 't call it QNH - it's the "Altimeter Setting" - speaks volumes.

[Pitch+Power]

easy-to-use map of transition altitudes in the UK?


Let's face it, the phrase easy-to-use and UK rarely appear together, except in a question as in this case.

The Americans have mastered the art of practicality in most aspects of life. Aviation is one good example.
Europe ( in particular the UK ) seems to take pleasure in the fact that they are stuck in the theoretical world.
Witness the typical response to a student in a flight school in the UK, who trained outside Europe (how dare they!) and asks about QFE, or to explain the transition level system here.

QFE should go in my opinion. If someone can't add field elevation onto the circuit height then, well.... :ugh:

[Thud105]

Of course QNH & QFE should go, along with the rest of the Q-Codes, RPS, signal squares, overhead joins and all the other archaic anachronisms that were introduced when Morse Code was the height of sophistication! When the pilot of an HP42 was trying to find Croydon in the 1930s they were relevant, unfortunately the UK has clung onto them ever since!

[vee-tail-1]

Well it makes it all sooo interesting when flying below transition level outside CAS. Other traffic might have RPS, QNH, QFE, set, and they might be talking to London info, or a local A/F , or even 'safetycom'. I like to fly at altitude plus 500 feet (as in France) to minimise the chances of an intimate encounter :ugh:

[Flyingmac]

QFE should go in my opinion. If someone can't add field elevation onto the circuit height then, well.... :ugh:

Call me dumb if you like but, how would joining a circuit on a QNH as opposed to a QFE benefit me?

[flybymike]

Precisely. I like to join the circuit at (say) 1000 feet above the field, and not one thousand three hundred and forty nine feet nine and three quarter inches above sea level...

[Dave Gittins]

Flybymike - Precisely. I like to join the circuit at (say) 1000 feet above the field, and not one thousand three hundred and forty nine feet nine and three quarter inches above sea level...

But when they are the same altitude what's wrong with joining the ccircuit at 1350 QNH and then you know exactly how high you are above all the things on your chart ??

[Flyingmac]

A VFR pilot's workload is highest during approach and landing. You want to throw in some mental maths for no good reason that I can see.

We don't have any field elevations high enough to justify a QNH approach.

Some airfields, such as Redhill, use QNH due to being in a CTR. The vast majority don't.

[mm_flynn]

We don't have any field elevations high enough to justify a QNH approach.

I think that is the essence of why QFE lingers in the UK. Pretty much all airports are at sea level and for the most part terrain around the airport is minimal. For VFR pilot why not twiddle a few Hpa on or off to get the needle to point at 1000 (assuming you have no intention of ever flying where the airports are not at sea level).

On the otherhand, I can't particularly see why a VFR pilot needs more than one mental math cacluation in a QNH system, to add 1000 to the field elevation to get the circuit height (which can normally be acheived simply by reading the pre-calculated number off the airfield plate). The rest of the process is by eye anyhow.

[Flyingmac]

There's always someone who wants to fix what aint broke.:ugh:

[Dave Gittins]

I'm not trying to fix anything, if it works for you to fly on QFE, Fly on QFE. It works better for me to use QNH. Pretty much everywhere I fly or have flown is close enough to controlled airspace or terrain for me to use QNH so I know my altitude is the same as everybody elses altitude and the numbers on the chart and I am not flying to a height.

The AIP Entry for Redhill sets out the local proceedures based on QNH.

http://www.redhillaerodrome.com/images/Downloads/egkr_aip_mar12.pdf

Look at "3. Redhill Local Flying Area (LFA) and Procedures"

I have never heard anybody either ask for or be given QFE

It works for me to have one universal process .... and I have flown around the US Airforce Academy.

[Flyingmac]

I don't fly around on QFE. Before leaving my strip I set the altimeter to airfield elevation. On return I wind it back to QFE. Simple.

[Thud105]

If you fly from a strip why on earth do you use QFE? Don't most farmstrip flyers just eyeball it?

[Crash one]

I seriously cannot see why we need several different Q things for altimeter settings. It seems totally illogical that the altimeter reading should need changing in the vicinity of an airfield. Shirley one setting based on a single base line should suit?
If everyone, including CAT below TL, were on the same setting & we all fly at 2000ft on the same setting, heading for the same spot, there will be an almighty bang! Which would be a simple thing to avoid.:ugh:
I may be missing something, but does an aircraft on an autoland approach rely on the altimeter setting (set by the Captain) to make a precision touchdown? I really don't know how these things work. If so, one digit out & it will land 32ft too early or late?
No doubt this argument will perpetuate ad infinitum. Can someone answer the question. How many CAS altitude busts are there in America caused by the pilot using the wrong Altimeter Setting compared to the UK? To my mind the whole confusing pile of utter ****e is a recipe for disaster. And it is high time the Government, CAA, AOPA, LAA, BMAA, BGA & Uncle Tom Cobleigh and all, including the Military, got their heads out of their arses & sort it out.
Just the opinion of a low hrs NPPL with a worn out altimeter setting knob.:{


If you fly from a strip why on earth do you use QFE? Don't most farmstrip flyers just eyeball it?


Yes. I remain on RPS till the a/c is in the hangar.

[Discorde]

From a Pprune thread a thousand years ago:

Having spent four decades flying aircraft both large and small 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 pilot’s 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 100 ft.

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?

[fireflybob]

Whilst I would admit to being a supporter of QNH only, it doesn't matter whether you use QFE or QNH so long as you manage the altimeter(s) correctly.

I am not at all surprised by the comments made by those who prefer QFE because they have probably never flown QNH only so it seems a bit like going to the moon for them.

I invite all those who fly QFE to trial flying QNH for, say. the next 20/50 hours - I think you'd probably find you prefer it after a while - there is far less significant change of subscale setting on a flight and therefore. I would suggest, less likelihood of incorrectly setting the subscale.

As has been correctly stated we don't really have any high elevation airfields in the UK but if you had learned to fly at Nairobi which is circa 5,000 ft amsl I don't think you would have been brought up to use QFE - or would you prefer to change the subscale by about 167 millibars (ahem I am sorry Hectopascals) every time you come back into the traffic pattern or whilst you are flying the missed approach from the ILS?

[RTN11]

I may be missing something, but does an aircraft on an autoland approach rely on the altimeter setting (set by the Captain) to make a precision touchdown?

Aircraft with Autoland would have a very precise Radar Altimeter which shows the exact HEIGHT of the aircraft above the terrain below, therefore the aircraft knows exactly when to flare and reads zero when the wheels are on the ground.

Funny how the thread stated with how we should get rid of QNH and has turned into getting rid of QFE.

For the people who use QFE it works just fine, most are occasional GA pilots who are happy joining a circuit at a known height. Some even fly an entire local flight on the QFE from wherever they departed.

It's one of those things that makes the UK different, and I don't see it changing anytime soon.

[Crash one]

Quote:
I may be missing something, but does an aircraft on an autoland approach rely on the altimeter setting (set by the Captain) to make a precision touchdown?
Aircraft with Autoland would have a very precise Radar Altimeter which shows the exact HEIGHT of the aircraft above the terrain below, therefore the aircraft knows exactly when to flare and reads zero when the wheels are on the ground.



I suppose I should point out that I was being a bit tounge in cheek there. It is pretty obvious that no auto system is going to rely on air pressure to land. Any more than it was used on the Moon.
No doubt QFE works for some people but that doesn't mean that it is ok to use multiple systems, just because this is the UK & we are allowed to be different. Personally I have done circuits at my strip without even re-setting the altimeter from several days ago, & prob on RPS then.

[ShyTorque]

Personally I have done circuits at my strip without even re-setting the altimeter from several days ago, & prob on RPS then.

Whatever you choose to do at your own strip, that would cause you to fail a CAA checkride.

Just out of interest, have you ever thought what you would do if you were flying locally on a "several day old" altimeter setting and inadvertently found yourself in IMC?

[ShyTorque]

Silvaire, the transition level(s) in UK are under total review by the authorities at this present time. At the moment we have areas with different TLs, which isn't ideal (!) but it's likely that the UK will have an overall raised level in the not too distant future.

I'm often given the RPS, usually by the military controllers but I don't often set it, preferring to use local QNH unless operating further than 25 nm from an airfield, such as over certain areas in the north of UK. At such times I wind it on the smaller, third altimeter for reference.

Having been trained by the military to use QFE and RPS as "bread and butter", I hardly ever set it these days unless directed to fly on it during a MATZ crossing. I would probably set it for training circuits, but very seldom do those as I don't fly for a training organisation.

[Crash one]

Just out of interest, have you ever thought what you would do if you were flying locally on a "several day old" altimeter setting and inadvertently found yourself in IMC?

Actually yes. Contrary to what you might think, I wouldn't be so bloody stupid as to get myself into such a position. However, IF I were that stupid I would call someone on the wireless & ask for the Local Regional QFE. Simples.
And if I were taking a CAA check ride I would behave correctly.
I like to enjoy my flying, I also like to practice flying the thing without ref to instruments, I like to practice accurate eyeball circuits & landings.
Or perhaps I should just say, Get a grip!!:ugh:

[flybymike]

However, IF I were that stupid I would call someone on the wireless & ask for the Local Regional QFE. Simples.
I have never heard of a local regional QFE, and my granny used to call them a wireless...

[Crash one]

I have never heard of a local regional QFE, and my granny used to call them a wireless...

Neither have I & so did my mum.:ok:
And it ran off an Accumulator

[chevvron]

Flyingmac: I don't know where you got your info about the 'vast majority' of airfields not using QNH, but it's not true, especially when you take into account the CAA mandate the use of QNH as the main pressure setting to be used below TA. OK the QFE may be available for those who 'have' to use it, but as the 'vast majority' of airfields use circuit patterns based on QNH, they're very much in the minority!
When an aircraft joins the circuit and I pass QNH, and the pilot reads back 'QFE is....' I often wonder how they manage to pass their biennial.

[peterh337]

I use QNH only.

QFE is pointless, and most airports are not going to give it to you anyway. The RAF ones still love it though ;)

I often wonder how they manage to pass their biennial.

You cannot fail the biennial, so long as the instructor is alive afterwards to sign your logbook.

[ShyTorque]

However, IF I were that stupid I would call someone on the wireless & ask for the Local Regional QFE. Simples.

Yes, if you were that stupid, you probably would! :D

[JW411]

I find some of the responses on this thread deeply disturbing. How on earth could you possibly have a Local Regional QFE? Bizarre.

[Flyingmac]

Flyingmac: I don't know where you got your info about the 'vast majority' of airfields not using QNH, but it's not true, especially when you take into account the CAA mandate the use of QNH as the main pressure setting to be used below TA. OK the QFE may be available for those who 'have' to use it, but as the 'vast majority' of airfields use circuit patterns based on QNH, they're very much in the minority!
When an aircraft joins the circuit and I pass QNH, and the pilot reads back 'QFE is....' I often wonder how they manage to pass their biennial.


Have you looked at a VFR flight guide lately? Try AFE. The VAST majority of airfields list their circuit heights as XXXXft QFE. QFE.QFE:ugh:


If you fly from a strip why on earth do you use QFE? Don't most farmstrip flyers just eyeball it?


Two very active airfields close by. I call one up for their QFE to ensure I'm above their circuit height.

[Crash one]

I find some of the responses on this thread deeply disturbing. How on earth could you possibly have a Local Regional QFE? Bizarre.

:ugh::ugh::ugh:

[peterh337]

The VAST majority of airfields list their circuit heights as XXXXft QFE.

That is no more than a shorthand for XXXXft above the aerodrome.

It doesn't mean the airfield will give you a QFE.

And no airfield abroad (that I know of) will give you a QFE.

[Flyingmac]

That is no more than a shorthand for XXXXft above the aerodrome.


That's why it's called Q.......FE. (Field Elevation).

[peterh337]

Yes, but what you are supposed to do is look up the published airfield elevation, add it to the published circuit height, and fly the circuit at that altitude.

QFE is useless once one has left the circuit.

[Flyingmac]

And no airfield abroad (that I know of) will give you a QFE.


Well, let's start with the nearest. LFAT (Le Touquet). Published circuit height. 1000ft QFE.

The list is very long.

Should you ever fly into my local airfield when I'm in the tower I will pass you the runway in use and circuit direction. Then I'll check the altimeter reads Zero, pass you the QFE and expect you to fly on it.

Hopefully you will fly the circuit at the correct height and your altimeter will be reading Zero on landing. If this is too difficult, there are other places you could go.:rolleyes:

[peterh337]

LFAT calls it "QFE" but they really mean "AAL".

They are doing this in the belief that they are doing the Brits a favour.

I have never come across a French (or any other non-UK) airport that actually passes the QFE value over the radio, or ATIS.

If this is too difficult, there are other places you could go

If you can advise your airfield name, I will take note (along with many others, probably) - not of the requirement to use QFE (which I can mentally and emotionally deal with) but of the attitude :ok:

[Tinstaafl]

...and then 'request QNH'.

[2 sheds]

Should you ever fly into my local airfield when I'm in the tower I will pass you the runway in use and circuit direction. Then I'll check the altimeter reads Zero, pass you the QFE and expect you to fly on it.

Hopefully you will fly the circuit at the correct height and your altimeter will be reading Zero on landing. If this is too difficult, there are other places you could go.

That is one hell of an attitude, Flyingmac. Do I assume correctly that it is yet another AGCS unit exceeding its authority? What right do you think you have to "expect" a pilot to comply with your personal idea of whether he should use QNH or QFE for approach and landing? CAP413 implies that, as at an ATC unit, both should be available. As peterh says, adding the aerodrome elevation to the circuit height is not exactly onerous.

2 s

[Jan Olieslagers]

First, for those with an interest, two observations from the continent:
-) here in Belgium QFE is never mentioned after the theory exams. In five years of flying I have yet to actually hear it on the radio.
-) whenever I call Brussels information after leaving my home field, and tell them my intentions, they will respond with "Roger, Regional QNH is xxxx" and I have known it to be 5 hP off from what I had set on the ground - and Belgium is not THAT big.

And now a bold and very personal opinion: the whole QFE vs. QNH argument is futile, almost moot. The real problem is that we still want to stick with barometric altimeters. But at the current rate of progress, it wil take several decades, if not centuries, before ICAO, FAA, EASA, and a zillion more parties agree to the use of GPS altitude.

OK, barometric has the charms of most antique techniques: simple and reliable. But if we took GPS as the prime information source, we could have a barometric altimeter as a backup, and twiddle the pressure setting without having to talk to anyone.

[Keef]

I was taught to use QFE when I did my PPL. Then I went on to do the IMC rating and was taught to use only QNH. Then I went to the USA and did a load of flying, and soon realised that there can't be a QFE for a lot of airfields there.

I don't use RPS (there's always a QNH to be had, in my experience), and I don't use QFE. Somehow, my poor brain copes.

On an IMCR or IR renewal, failure to set QNH on the missed approach is an automatic "fail", which is another good reason not to use QFE.

[BillieBob]

I find some of the responses on this thread deeply disturbing.Me too, like the suggestion that spatial awareness could be significantly affected by the need to add airfield elevation to circuit height in order to get circuit altitude. Anyone who can't manage simple addition shouldn't be riding a bicycle, let alone flying an aeroplane!

[Flyingmac]

Yes, but what you are supposed to do is look up the published airfield elevation, add it to the published circuit height, and fly the circuit at that altitude.




I can't for the life of me, see why anyone would PREFER to fly a circuit with reference to sea level . Maybe they just like to complicate matters.

I'm off flying. 30th anniversary of me taking to the air:)

[patowalker]

...and then 'request QNH'.

... and that means Query Newlyn Height

[stevelup]

I can't for the life of me, see why anyone would PREFER to fly a circuit with reference to sea level . Maybe they just like to complicate matters.

Because (as has been mentioned several times now), at many locations, it's physically impossible to even set QFE on the altimeter.

I toured down France last week to Cannes and never heard QFE mentioned once. It does seem to be a very British thing.

Also, when landing back at my home base, there often is no radio, so the circuit would need to be done based on QNH - I found it easier to ditch QFE because it adds a layer of inconsistency.

Two very active airfields close by. I call one up for their QFE to ensure I'm above their circuit height.

You talk about over complicating things - surely it would be easier to just add the AD height to your current altitude rather than making a radio call and temporarily resetting your altimeter?

[24Carrot]

I can't for the life of me, see why anyone would PREFER to fly a circuit with reference to sea level

Another motivation, in some cases, is the need to avoid airspace as well as the ground, and the lower airspace ceilings are at a QNH altitude.

For example at Redhill, where the nominal 1000' circuit height is 300ft below the class D and so you will want a circuit altitude on the same QNH as Gatwick. Especially as the class D extends beyond the ATZ.

Conversely, White Waltham, with a higher surrounding Class A ceiling to the West, flatter surrounding terrain, and a slightly lower elevation, gets by with a lower 800' circuit height and QFE.

[Whopity]

It does seem to be a very British thing.Indeed it is. Over the years QFE has survived due to RAF fighter pilots who like to relate everything to the airfield they took off from. I recall the RAF changing to QNH at some time back in the 80s, but it was short lived, within 9 months the decision was reversed. GA has largely followed their lead. Even MATZ crossings are given on QFE!

It is only a matter of time before we raise the transition altitude, get rid of RPS and operate on QNH, but if the RAF still insist on using QFE, it will surely continue in UK GA.

[Jan Olieslagers]

Well, you'll please excuse me for repeating myself, but it is only a matter of time before we abandon barometric altimeters* and with them the whole rubbish of QNH and RPS and transition layer and what not.

I must admit, though, that the time might be long.

*except as a secondary, redundant source of information, see earlier

[Crash one]

Well, you'll please excuse me for repeating myself, but it is only a matter of time before we abandon barometric altimeters* and with them the whole rubbish of QNH and RPS and transition layer and what not.

I must admit, though, that the time might be long.

*except as a secondary, redundant source of information, see earlier

This is all very well but would no doubt require GPS to be certified.
All very well for the CofA types/CAT etc but at what cost to the Permit brigade?

[BackPacker]

Yeah, and what would we bitch about here on PPRuNe?

If we abolish arcane stuff like QNE, QNH and QNF for GPS altitue, hand flying skills for autopilots, PFLs for BRS and so forth, we might as well abolish private flying altogether and fly commercially everywhere.

[Jan Olieslagers]

@crash1: That is a valid point, though I am not personally concerned. However it will not be long, certainly less long, before any serious overland flying will require a certified mode S transponder anyhow, and in any practical implementation this includes a certified GPS function.
For myself I'd rather spend my cash on a decent altitude measurement than on publishing for all and sundry where I am flying.

@BackPacker: yes, that is a much harder nut to crack, indeed. But as I read these pages, I feel confident the RAF will take care of that part.

[Crash one]

We could always resurect the stall speed AoA thing, that always winds up the Instructor camp:ok:

[Crash one]

Talking of Mode S, can someone please explain why, a piece of electronic equipment should cost so much more than any other piece? Just because it says Aviation on the tin? I really don't know just how super special the component parts are within such a device. One can buy the most super computer for a fraction of the cost.

[Jan Olieslagers]

High cost of development, high cost of certification. Worst of all: Small market, i.e. not many units sold, to share that initial cost.

Remember the first CD players, or the first video recorders, or the first mobile phones? All were initially quite expensive, but their price soon fell dramatically. That fall is not going to happen to avionics, more's the pity.

[mm_flynn]

Talking of Mode S, can someone please explain why, a piece of electronic equipment should cost so much more than any other piece? Just because it says Aviation on the tin? I really don't know just how super special the component parts are within such a device. One can buy the most super computer for a fraction of the cost.

THis is true for all aviation parts. It is the cost of the administrative overhead for certification. I have a broken A/C compressor on my aircraft. The part is an industry standard automotive part (exactly the same spec/part number etc.), however, the part with a yellow tag is 3 times the price of the part without. This is one of the great joys of the LAA/experimental aircraft world - you do the QC yourself so parts are vastly less expensive.



I can't for the life of me, see why anyone would PREFER to fly a circuit with reference to sea level . Maybe they just like to complicate matters.

When just going round the circuit it is convenient. However, if there is any possibility you may need to depart the circuit, or if their is complex terrain near the circuit, or the airfield elevation is such that you have to wind on more than a few MB, or you are complying with an ATC altitude on the way in, or ... then QNH is a lot easier and safer.

[peterh337]

Talking of Mode S, can someone please explain why, a piece of electronic equipment should cost so much more than any other piece?

1. Small market (not always - Garmin have shipped vast numbers of GNS boxes)
2. Certified kit cannot be sold direct so dealer margins need to be built in
3. Certification is not cheap (though immaterial in the long run; most "boxes" we know became pure cash cows long ago)
4. Avionics that sell successfully (Garmin, Garmin, etc) are very profitable ;)
5. It's always been that way, and in business you never bomb the market price even if you can :E

FYI - the cost of building a GNS430W is about $300. The cost of building a GTX330 is about $150.

[Crash one]

Thank you all, typical rip off as I would expect.
Doesn't this sort of thing encourage the "black market". Shirley it wouldn't be difficult to clone such stuff?

[Jan Olieslagers]

Cheese us! If it's not difficult in your eyes, go for it! Just do it, man! There's money to be made, there!

[Crash one]

Shhhhhhhhhhh

[peterh337]

Doesn't this sort of thing encourage the "black market". Shirley it wouldn't be difficult to clone such stuff?

It's a good Q and the answer is more subtle than one would think.

The sales of certified avionics are almost totally dependent on the loyalty of avionics installers who in most cases recommend the product and in virtually all cases install it.

The big names like Garmin and Honeywell (notwithstanding the fact that Honeywell washed their hands of GA avionics about 15 years ago) have massive dealer/installer loyalty.

This reseller pipeline is not easy to convert to selling something new.

Their gross margin (i.e. the dealer discount) is of the order of 25%, so if you get a quote for a £10k box with a £2k install cost, the installer is making £2.5k just by ordering the box, plus the £2k installation fee. If he didn't make the 2.5k (if e.g. you buy the box discount from the USA by mail order) he would have to charge you £4.5k for the installation, to make the same money overall. So selling a £5k box which does the same job is completely not in their interest - unless they sell at least 2x as many, which is unlikely given the fairly stagnant market.

Next comes the mfg support. While there are some smart avionics installers, most IME are just wiremen who pick up the installation manual for the box, turn to the back of it where the wiring diagrams are, and they pick the one which most nearly represents your existing aircraft equipment :) It really isn't rocket science, in most cases. This also means that many installers get themselves into a total pickle when they are asked to do something not trivial, and often deliver installations that are only partly functional (e.g. an EHSI installation where the course pointer does not go back to the GPS, for OBS setting purposes). A chinese mfg is unlikely to deliver much support to the installer.

A straight copy (counterfeit) is going to fall foul of copyright laws, etc.

It's not easy today to take on Garmin. Look at where Avidyne are. Talk talk and more talk, and it's obvious they have lost the plot. A once mightly company is IMHO surviving on the sales of old cash cows like the TAS600.

The stagnant market, and the fact that so much GA is so tight you could not get a #1 Pozi up their back end, means that anybody doing a Mode S transponder (and there are several people doing them) is going to price the product only just below Garmin's price. You can call it a ripoff but it's really only good business :) If you get aggressive, and get visibly successful, Garmin can just halve their prices overnight and still make a gross margin of some 80% :) And wipe you out.

If one could sell certified boxes direct to users, everything would change. You would have full featured autopilot systems for a few k, etc. Look at the US Experimental scene...

Certification cost is not a major thing, a few years down the road. It is mostly affected by how well you know the process, and the big names will have staff in-house who know exactly what to do. A newcomer will be starting from scratch.

It's the same in non-aviation certified areas; try getting a BASEEFA approval for a product from a company nobody has heard of. The BASEEFA officer basically tells you to ***k off, probably because you are delaying his lunch date with the rep from one of the big names :) You will get much the same response on your first contact with the FAA or EASA. Relationships matter..........