QFE why?

[A and C]

Can some one please tell me why the RAF/RN insist on using QFE for instrument aproaches when the rest of professional aviation went to QNH years ago ?.

[N Genfire]

Because we can, and we like to know where the ground is when we are snurgling around VMC at 300 feet.

PS. The Army use it too, yes we do have aircraft.

Regards N Genfire

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Not if I can do it tomorrow.........

[NoseGunner]

The Armed forces do periodically try going to QNH but at the end of the day it's much nicer having an instrument instantly telling you how high you are above the airfield than having one with a random number on. I know its only a simple calculation but in a high workload enviroment, the less simple calculations you have to do, the better. (Jeremy Clarkson's Speed explained it all very well I think).

[Gimme300]

Err, because its nice to know that when the altimeter reads zero one arrives at the ground????? We went to QNH, but obviously our simplistic military minds couldnt cope with that as there were several incidents so we reverted to QFE. What do you mean by 'the rest of the professional avaition'???? Had QFE passed straight away without asking across the UK, France, Netherlands, Belguim so I dont think we are that peculiar. As we are on silly altimetry questions, why dont the Americans use millibars or hectopascals like the rest of professional aviation????? ;)

[airforcenone]

Call me old fashioned, but we have a RADALT and a firm voice which yells if you get close to the ground.

Mind you, I spend my days rather higher than 250ft so my point may be irrelevant. However, unless you're over Holland or south Lincolnshire, the ground isn't particularly flat so what use is QFE then?

[Scorpius]

It's not only the Americans who use inches of mercury - all the E3Ds at Waddo use it.

[N Genfire]

We only use it at airfields, AFnone. As the above posts have allured to its nice to know when popping out of cloud at your minima that your radalt and bar alt should read the same, we have no fancy gizzit gadgets to shout at us, or land the plane for us.


Regards N Genfire

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Not if I can do it tomorrow.........

[EESDL]

Airforcenone
Obviously, if you were flying low (is there another way?)over Holland or Lincs, I'm assuming that you'd be on the 'regional' and not some irrelevant QFE!!

As a Truckie pilot, most of our approaches around the world, aswell as being slow, are also on QNH. Nice to come back to Blighty and shoot a PAR with a large dial on the dashboard that indicates the ht above the threshold.

Perhaps if all the other 'pros' that you mention used QFE, then the extra capacity thereby saved could be used to reduce the incredible number of occasions when the crew lose SA and CFIT reigns? Small point, and honestly it makes little difference in my job.
Has anybody had an occasion when they couldn't actually dial the QFE up due to airfield elevation?

[BEagle]

Yes - Colorado Springs, Buckley, Cannon to name but 3.

[A and C]

Gimme 300 i cant think of an airline that uses QFE now and the latest NG737 flight manual warns you not to use QFE as the FMC will not like it !(can the C17 use QFE?) I can see that QFE could be a good thing for the fast jet people who dont have ILS and the only option would be a PAR but for the rest of the militry i cant see how the height above the runway helps you avoid all the other obstructions.

I have to say that i think that changing the setting of the altimeter at a critical and high workload stage of flight is asking for trouble but i am willing to be enlightend on this subject.

[Blue Stuff]

Where do QFE / QNH originate from? I know that they are not actually abbreviations. Were these terms not originally wartime designations? I also seem to recall there having been other 'Q's which have fallen into disuse. Boring question, I know, but I'm curious. Can anybody enlighten?

[DouglasDigby]

Blue Stuff, I seem to remember that the "Q" abbreviations were introduced to assist in those difficult days of early HF/morse transmissions. You're quite right, there was a huge list of them (QSY = change freq) - maybe a siggie from Kinloss still has his original list on parchment somewhere!

Some are listed at http://duke.usask.ca/~buydens/ham/qcodes.html

[Thud_and_Blunder]

Blue Stuff,

In my previous military incarnation I worked in an army trade where a working knowledge of the more common Q and Z codes was essential. Why not try what I did - do a Google search for "Morse Q codes"? It threw back over 5000 replies, showing that the aviation use might be dying out but the radio hams still love the brevity of the things.

For some reason, the code QRM ("I am being manually interfered with", followed by a number from 1 to 5 showing the strength of interference) springs back to mind... Strange people, those signallers.

[Hong Kong Fuey]

I think EESDL and BEagle have highlighted why most of the world uses QNH - there are a significant number of airfields where the elevation is so high that setting QFE would entail a lot of dial twisting or is even off the scale. The UK, France and the low countries, as mentioned in a previous post, don't have any such airfields and so can quite happily provide a QFE approach.

Toodle pip.

[Wholigan]

All the above absolute bollox --- it's 'cos we want to and sod the rest of you! :) :) :t

[Firestreak]

When you are sat in your cockpit, all on your own, trying to get the jet on the ground (either with or without ATC help) in nasty weather with sod all fuel to divert, only one thing matters; height above the runway when touchdowm height=zero

[Gimme300]

A and C - Wanst the topic on why the british military still use it rather than airlines? Maybe we prefer QFE because in my military aircraft (and I know others do before I get flamed!) unlike an airliner, I do not have ILS, an autopilot or the ability to unstrap and walk around if I get tired! Not saying that Airline Jet pilots dont work hard, but by the time landings come along in our 'always manual land aircraft', either visually in good weather or via a PAR in bad weather, you are knacked, and want things nice and simple. The simplest thing is for the ground to be at zero ft when you land, hence we use QFE. I am sure that the obliging military air traffic would provide you with the QNH if you turned up in your NG 737, but we like it simple :)

[This message has been edited by Gimme300 (edited 26 June 2001).]

[Identified]

Cause I'm a sad man:

(Q)FE = Field Elevation
(Q)NH = Nautical Height

[BEagle]

I was once taught that the UK civil system was:
QNH with ApproacH
QFE with TowEr

[SWB's Mate]

As we're on Q codes, why QNE, QTE, QDM, QNR, QSY, etc. etc.? My understanding is that when the codes were decided on for wartime use in the 30's and 40's they did not necessarily have a bearing on whet they actually meant. It was just a list. Anyone know any better?

[Flatus Veteranus]

Q Code goes back to WT days before the war. Dits and Dahs and all that. I think the SOP on Vulcans was QFE on Captains alt. and QNH on Co's.

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presto digitate

[RMPA]

I've operated mainly as a military pilot, both in the RAF and with the USN, but lately I've been a civvy. Whilst operating in an aircraft with a limited bang seat performance during and immediately after take-off I suppose it was nice not to have to do a sum when it all turned to s**t, but that sum could easily have been performed prior to the excitement. Since the height of ground is usually referenced to sea level it makes sense to me to use QNH. This is especially true if the RAF are planning to operate aircraft with reasonably modern equipment like EGPWS, where the terrain database is also referenced to QNH. We will make this clever system, which will be fitted to Nimrod MRA4, ASTOR and A400M (and anything else that comes after them), completely useless during the approach. Any long range aircraft operators will be used to using QNH anyway; asking US and many other controllers for QFE will cause more problems than it will cure. How clever is a system that: 1) Is different to everybody (just about) elses. 2) Disables equipment that is designed to protect you. 3) Requires two different pressure settings to be set during the transition to an approach. If we are flexible enough to use QNH when we go abroad or go to civil airfields, how about being flexible enough to allow those Groups within the RAF to use the system that is appropriate to their operations, rather than impose the limitations, largely brought about by fast jet operations, on everybody. If it is not FJ ops, but rather Training Command that has imposed QFE on everybody, then we have a serious case of the tail wagging the dog.

[Mmmmnice]

Woah boy geek alert! I'm no statistician but I'm sure someone out there can come up with the proof that more "professional" QNH users have CFIT incidents than out of step military aviators. The real problem comes when some joker decides to change a system that everyone understands; so I guess it's back to QNH apps next week then!
PS. I like QFE but I'm not really paid enough to care that much - coming through ready or not...........

[Uncle Ginsters]

Chaps, i think the real question here is " Why do the rest of the aviation world use QNH?" Surely the most important factor in an approach is your height above the TDZ? Obviously in places that would require a huge wind (Nairobi, Calgary etc...) it makes sense to use an alternative, but in this country?

And in answer to the 'Q' question, 'Q' is the scientific denominator for pressure. As stated before, the 'FE' and the 'NH' should really be subscripts and stand for Field Elev. and Nautical Ht. Wish i could help with the others but i've never really heard of any of them,

Smiles,

Unc.

[This message has been edited by Uncle Ginsters (edited 30 June 2001).]

[Blue Stuff]

Thanks all for your answers to the 'Q' question. I seem to remember the term from my fluid dynamics ...

Speaking as a relatively baby pilot, it seems much more sensible to read your height relative to the aerodrome on T/O and Ldg. After all, you don't particularly care about anything else in this scenario. If you're low-flying, the RPS is useful, and if you want flight levels, set SPS. A case of horses for courses, is it not? I suppose QNH might come in handy if flying a Catalina ... :)

[mr hanky]

Sound the geek alert again! Hate to rain on your parade Uncle G, but I think the answer must be something different, given that 'q' only refers to dynamic pressure (.5 x density x speed squared) not atmospherics, and that some of the abbreviations have nothing to do with pressure anyway (eg QDM = runway heading, from what I remember). Any more theories out there?

[Thud_and_Blunder]

Blue Stuff,

No, the Q (and Z) codes were not avation-specific. An instructor of mine in my pre-aviating days gave me a potted version of their W/T origins, and opined that Q and Z were the best with which to begin the trigraphs as they are the longest Morse letters that won't easily be confused (by a tired listener) with numbers. Bear in mind that a lot of codes were sent with quantifying figure-groups immediately afterwards. Most users only needed a small easily-remembered selection of the codes for normal ops - the complete list would've taken up too much room in the average W/T operators workspace.

[Harry Peacock]

Used both systems and personally prefer QFE but no one really worries about my opinion anyway.

One point though cloud base is given relative to the airfield so when calculating alternate requirements etc you've still got to do some mental gymnastics adding this and subtracting that etc. ..... and the approach plates print both heights for minima's anyway!
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QFF is the setting on the sub scale that gives the same reading as a known datum eg. Rad alt reading or A'field reference points.

[Out Of Trim]

Mr Hankey, I believe QDM = Magnetic Heading to Airfield Overhead. QTE = True Bearing from Airfield to the Aircraft. QSY = Change Frequency.. QNH & QFE already adequately explained.. but seem to remember QGH but can't remember quite what that refers to..

[ 09 July 2001: Message edited by: Out Of Trim ]

[Whipping Boy's SATCO]

QGH - Direction finder homing and procedural approach technique. Still in use at the odd airfield.

[Thud_and_Blunder]

I think QGH was a controlled descent through cloud - a DF-based ATC procedure for getting a/c down into the overhead of the r/t aerial when all other means had failed. You could hear the controllers morale hit rock bottom when you requested it...

[G Fourbee]

There was also the flame-out QGH - beautifully introduced by an Acklington controller as "inrease speed, commence spiral left, call Cardinal Puffs with pints!"

[Flatus Veteranus]

You should have heard the Approach Controllers at Driffield and Middleton in the bad old days, when they had to cope with several aircraft on QGH at once - particularly before they got CRDF and had to get the QDMs by squawk-box from a manual homer. We took our hats off to those guys! Incidentally, QTE was the True bearing of the aircraft from the station. "They" would not put ADFs in the Meteor or Vampire because Fighter Command, who laid down the policy, only operated within an elaborate fighter ground environment (unlike MEAF and FEAF). The RAAF Meteors sent to Korea were, I believe, fitted with ADF. If the RAF aircraft had been, quite a few aircraft (and lives) might have been saved.

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presto digitate

[Cahlibahn]

There are hundreds of the buggers! (Q codes, I mean)

See
http://massis.lcs.mit.edu/telecom-archives/archives/glossaries/old.aeronautical.signals

[Gash Handlin]

And if you were an RAF Newton controller you would do three/four QGH's an hour as the trips came back on a 8/8 day as there wasn't a radar, thanks guys it was an amazing confidence booster doing a practice IF approach and having a look out the window to see you're being turned in exactly the right place when the only aids in the tower are DF and a stopwatch.

[N Genfire]

QSY ?

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Not if I can do it tomorrow.........

[BEagle]

There was, of course, the trick of arranging with 2 or 3 other mates a little jape to confuse the QGH controller. The team went to pre-arranged positions about 20 miles from the aerodrome all of which were equally spaced around the points of the compass. After the warning double-key on the frequency was given, they would transmit in sequence: 'True'..'Bearing'..'True'..'Bearing'..'True'..'Bearing'..'Cr anwell'..'Homer'..'Request'..'True'..'Bearing'; each pilot only transmitting when it was his turn!The 'wiggly worm' would dart around the CRT and ATC would go nuts!

Or orbiting that mast down near Melton Mowbray when the 'welease Wodewick' contwoller was on shift and asking for a Twue Bearwing....the answer was 'Two two two degwees Twue'!!

Rotten little $ods, U/T pilots!!

[pana]

To N Ginefire:
Army can have aviation, but do they have pilots?