Setting QFE when no airfield info or air ground

[gingernut]

Had a fantastic trip (VFR) from Manchester to Tatenhill last week. All went well, but I always like to reflect on anything that could have gone better, and so I pose these questions!

I phoned the airfield to PPR prior to the trip, and was told to call blind when approaching.

In the absence of QFE setting from the airfield, I made a calculation using the last known QNH (from Shawbury), and the (known) elevation of the airfield.

Is this acceptable, and could I have done this a different way ?

thanks in anticipation

[FlyingForFun]

In uncontrolled airspace, I don't believe there's any requirement to have any specific value set - use whatever you're happiest with, as long as it allows safe flight.

In that situation, personally I'd stick with a QNH, and fly a circuit at the airfield elevation (which I can read off the chart) plus 1000' (or whatever local procedures dictate). Have used this procedure quite happily at airfield with no radio (whether closed, un-manned, or farm strips with no frequency) in the UK, France and USA without any trouble.

FFF
--------------

[IO540]

What would be the views here on always using QNH (never QFE)? That's what I do. There's a lot going for it - even for purely VFR flight where one is going to a field for which no QNH/QFE is available but there is a nearby field (perhaps with ATIS) whose QNH you can use.

[Tinstaafl]

I never use QFE. Always QNH. VFR & IFR. Much easier with no stuffing around in the missed approach etc AND for terrain clearance puts you on the same datum as all those chart elevations .

[Chilli Monster]

I'm a 'QNH person only' too. Adding airfield elevation to circuit height is no great problem, and, as you say, you can always get a QNH from a nearby ATIS or airfield if the place you're going into isn't available to tell you.

[Flyin'Dutch']

GN,

That is the most sensible approach in my opinion and ensures you are not going to be a million miles out.

When just doing some circuits it is not going to matter too much whether you use QNH or QFE.

Once you move away from the field it is easier to use QNH and in IMC using QFE is too complicated for my simple brain.

FD

[Aim Far]

What would be the views here on always using QNH (never QFE)?
And maybe we could call it "altimeter" too...
And set the transition altitude at 18,000 so we didn't even have to use the...er...other Q code
:)

[WestWind1950]

Only the glider flyers use QFE over here... QNH (when unknown, setting field elevation while on the ground) is really the only sensible thing to use. I can't believe that it is being taught to set your altimeter to QFE! That changes much more often then the QNH during ANY flight (except patterns, of course)!

Westy

[gingernut]

Cheers chaps.

I guess I'm in the habit of setting QFE, as this is what I've been taught.

My problem is, I sometimes find it difficult to perform the simplest of calculations whilst flying (fine on the ground !), so perhaps sticking to QNH would cut down the margin for error. (Although, some basic mental arithmetic would still be required in using the altimeter, say if the circuit height was non standard eg 800 feet.)

[Tinstaafl]

Adding 800' is easy: add 1000' and back off by two 'hundreds' divisions on the altimeter.

[On Track]

In this part of the world QNH every time (up to 10,000 feet).

I wonder how many countries use QFE at all... is Britain the only one?

[Tall_guy_in_a_152]

I would always use QFE if it is specifically offered (and it usually is at controlled fields) but would never bother to calculate it otherwise.

I was taught to set QFE when the field is in sight, but this caught me out when flying into Rochester for the first time on Friday. Approaching from the South West, the airfield 'nestles' beyond a line of hills so I was virtually overhead before I saw it (aided by a big arrow on Penguina's new GPS). Result was that I was twiddling the altimeter and descending dead side at the same time, and could not cross-check the indicated height against original altitude. If I find myself in the same situation again, I think I would leave QNH set.

TG.

p.s. Rochester very friendly airfield and the cafe met the high expectations indicated in another thread recently. Unfortunately we were a bit rushed so only had time for a piece of cake (sorry, gateaux au chocolat) and some soup. I will return.

[tmmorris]

I'm sure I asked this before and didn't get a reply, but... why are the RAF so keen on QFE, then? Surely they must see an advantage? Or are they (we, I should probably say...) so hidebound they can't see any advantage in changing?

Tim

[slim_slag]

only time I ever use "QFE" is when doing aerobatics as it's nice to quickly see how much room you have below.

[FlyingForFun]

.....as it's nice to quickly see how much room you have belowSo long as the area where you're doing your aerobatics is near enough the same elevation as the airfield whose QFE you've set, of course!

In my limited experience, I've only ever seen a QNH used for aerobatics, since it lets you compare your altitude with that shown on the charts. Mind you, I've also only ever done aerobatics so high that the ground really ought not to be an issue. What do all you more experiences aeros pilots set???

FFF
----------------

[slim_slag]

FFF,

Notwithstanding (if in USA) FAR 91.121 :E

Lets assume you accurately need to know the altitude of the terrain you are peforming aerobatics over. So (for instance) if the box is 200ft above the airfield, when still at the airfield set altimeter to -200ft. When arriving at the box you will have a decent "local QFE" setting dialled in and immediately obtainable from altimeter. You will have to make the same adjustment when using QNH, but this time you read the altimeter and make the adjustment in your head, which is another thing to do when you might be otherwise busy.... Works for me, others might do otherwise, and that's OK by me too.

PS FFF,

Might be a problem if field at more than a few thousand feet, could be a pain to wind altimeter back to zero, not had that problem myself though

[LowNSlow]

I was taught to use QFE when doing circuits, maybe it's because it's easier for students to see cross reference what the altimeter tells them and what they see out of the window when approaching to land.

The only time I've used QFE in the memorable past was yeasterday going into Wellesbourne and that was only cos it was offered and the circuit height is referenced to it.

[IO540]

slim_slag

In fact one cannot wind the altimeter back to zero from that far up, which is another reason for using QNH only, and in countries which have high elevation airfields you presumably don't have a choice.

[slim_slag]

Sure IO540, will not work at higher terrain, but never been relevant to me or most people I suspect. I don't think that is a good reason to use QNH only, and I am not telling you not to use QNH :)

Wasn't that Thunderbird crash blamed upon pilot error and altimeter settings, and having to make calculations in his head about MSL and AGL?

[Whirlybird]

I'm a little mystified about all the opinions. What does it matter whether you use QNH or QFE, so long as you know which one you're using? I personally find it easier to use QFE if doing circuits or approaching an airfield, so that I know the airfield is at zero ft. I can see it's equally logical to not want to have to set something different, and therefore stick to QNH. But I really can't see that it matters one way or the other.

[IO540]

Whirly

For flight in VMC it doesn't matter, but then if always in VMC you don't really need an altimeter (for terrain clearance) because you aren't going to fly into terrain anyway.

[M609]

Must be mostly flat terrain around the airfields in th UK, coz imagine airfield at aprox 250ft, terrain within 4nm of the field as high as 5000ft..... Then QFE is completely useless...... :ok:

[slim_slag]

IO540,

For flight in VMC it doesn't matter, but then if always in VMC you don't really need an altimeter (for terrain clearance) because you aren't going to fly into terrain anyway.

If only that was true, CFIT is one of the biggest killers out there :( 48% of CFIT occur in VMC (http://www.cami.jccbi.gov/AAM-400A/Brochures/CFIT.htm) I'm sure it's been said before, but....

Obstacle clearance at night, mountains measured in MSL (QNH)
Obstacle clearance in marginal yet legal VMC, again mountains measured in MSL (QNH)
Charts, at least in the US, show a safe altitude in each "sector", measured in MSL (QNH)
Safe (or legal) altitudes when over built up areas, charts show MSL (QNH)

And although you did say only for obstacle clearance, you need QNH on altimeter in VMC for correct cruising altitudes, measured in MSL (QNH)

[IO540]

slim_slag

My response to Whirly was tongue in cheek :O

Of course one needs an altimeter, and using QNH only not only gives you immediate and permanent terrain clearance reference right in front of your nose, but also removes some easy to make cockups when doing e.g. missed approaches. You can get yourself killed very easily around e.g. Biggin Hill (a mere 600ft bump) if you get the two mixed up.

I think life is different for helicopters because they tend to fly low anyway, following the ground. They also have a load of accidents; not sure if the two are related directly.

[2Donkeys]

Its never a bad idea to rely on what you were taught, so if QFE makes you happy, then use it.


But... I have a lot of sympathy with IO540's views. The rest of the world, without meaningful exception seems to get along very well without the concept. In my own flying, I like to keep the number of actions I have to complete before landing to a minimum. One less thing to screw up is the QFE/QNH setting. It is not at all uncommon to take off from an aerodrome under controlled airspace with the QFE set after a few circuits, and bust the overlying airspace. Just ask the boys at North Weald.

Simple is good. Always fly on the appropriate QNH or 1013 and you have reduced the chances of a misunderstanding.

If when I get close to an airport with a normal traffic pattern I can't add 1000 feet to its elevation and fly the circuit visually, then I probably shouldn't be flying at all. If absent any A/G or other indications of QNH/QFE I can't judge an appropriate circuit height by looking out of the window, then I should also have to hand my licence back. What are people taught for PFLs these days? Should I ask the farmer for his QFE before dropping into his field?

All IMHO of course!

2D

[slim_slag]

IO540, I think we agree. I use QNH exclusively, except when deliberately in unusual attitudes.... Not a rotary pilot myself, but from hanging around with helecopter medivac crew I get the feeling that hitting obstacles when flying in VMC is the big killer, but I know for a fact that none of the pilots use QFE. Regards.

[Whirlybird]

Perhaps I should remind you all that I'm a f/w pilot too on occasion. A bit more recently since I got a share in a C150.

Anyway, I still don't get it. The argument I mean, either side of it. OK, bearing in mind you're only likely to use QFE when departing or arriving at an airfield....

If you set the QFE, it's one less thing to think about when the workload is high. The elevation of the airfield I mean. OTOH, if you don't set it, you can't forget to, but you do have to add a few hundred feet to your altimeter reading. Swings and roundabouts really. A non-argument, I would have said. But hey, don't let me stop you enjoying yourselves. ;)

Concerning airfields in Britian on flat land, Caernarfon isn't, for one. Neither are Shobdon and Welshpool from some directions. If you approach either, you set the QFE after you've cleared the hills. If you're a QFE-setter, that is. Not a problem really.

One time when it's nice to have QFE is if you're overflying an airfield or MATZ, and want to make sure you're out of their zone. Now of course you could get out your Pooleys, check the elevation and so on, and yes, maybe you should have done that in advance...but maybe you're diverting. But so much easier to just ask for the QFE, isn't it?

Lastly, some of us helicopter pilots don't skim the ground all the time. While it's lots of fun, (a) it's not terribly safe, and (b) I'd rather not fall foul of the CAA for breaking the 500 ft rule. :eek: But then, I guess I'm getting to the stage of being old rather than bold. :{

[2Donkeys]

get out your Pooleys, check the elevation and so on

Or you could look at the map. The elevation is actually on the map next to the airport name.

2D

[slim_slag]

Well Whirly, hate to argue like :), but best thing is to only change altimeter settings when you have to, less opportunity of introducing error that way. If you have found the field using QNH, and you can land using QNH, don't mess with anything is my advice.

And if you haven't already dialled up the wrong setting in your altimeter yet, I promise you that you will.

[Whirlybird]

And if you haven't already dialled up the wrong setting in your altimeter yet, I promise you that you will.

Oh...I probably have. Same as I've probably subtracted wrong, or forgotten the airfield elevation, when using QNH...I've flown in the US you see, so I've done it both ways. ;)

And that's my point. Either way, it should be easy. Either way, being human, it's possible to make a mistake. So while an individual may know whether he or she is more likely to make a mistake with simple arithmetic or an altimeter setting, for some of us it really is swings and roundabouts, and I doubt if you can generalise.

And in case you wonder what I mean, I'm thinking of inexperienced f/w pilots, like me...since my f/w flying is always a bit rusty due to spending lots of time flying whirly things. So when I'm trying to land these infernal things with non-whirly wings that require me to keep up my airspeed on final, I like to do it by numbers like a beginner...turn final at 500 ft, 200 ft carb heat to cold etc. I really really don't want to be thinking...turn final at 500 ft, plus...was it 200 or 300, dohhhhh, I've forgotten! Of course, when you're in practice, it's no big deal. But there are more pilots out there who need the numbers than don't, I think.

[Hansard]

Flying commercially (fixed wing) or PPL with IR, QFE almost ceases to exist

[On Track]

Still wondering if anyone can answer my question: How many countries use QFE at all?

As far as I'm aware, nobody in my part of the world uses it.

You certainly won't get it from any ATIS or AWIS in Australia or New Zealand.

[Keef]

I was taught to use QFE when I did my PPL, because it made it easy to learn to relate the view out of the window to the height I was at. Probably the easy way to learn to relate glidepath to height etc.

When I did the IMC rating, I got fed up with having to remember to change back tio QNH on the missed approach (a "fail" if you don't do it). I stuck with QFE a bit longer, but then flew in the USA and that convinced me that it's QNH all the way!

It's SO much easier doing IFR approaches - the altitudes are all written on the plates anyway, and reading that the MDA is 248 feet is just as easy as reading the MDH is 200 feet.

But WHY do people keep trying to tell me that QNE means 1013.2? It doesn't!

Whirly - by the way, QFE and QNH at Caernarfon are rather likely to be the same, aren't they?