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Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 9:40 am
by rdfb
Sooty25 wrote:Whilst the whole flight was one full of errors (all mine), QFE, would have prevented the workload induced one that nearly bent the aeroplane.


It sounds like what really caused the first error was confusion between altitude and height. QFE might have worked for you, but only because this is what you expected, out of habit, when you added elevation on that extra time.

In a parallel world where everyone flies on QNH and QFE isn't a thing, I don't think you would have done that, because you wouldn't have had that habit. You wouldn't ever have to calculate circuit altitude, since that'd always be published directly as an altitude (eg. see the US).

I'm not trying to argue that nobody should ever use QFE here. Everyone's responsible for themselves and needs to decide for themselves what system they want to use. I just wanted to point out possible sources of error that it seemed to me that others hadn't considered, so that everyone can form their own properly considered opinions.

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 9:45 am
by cotterpot
It helps if you have 2 altimeters :wink:

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 9:54 am
by skydriller
I have just read your post, and firstly Id like to thank you for recounting your story for others to learn from. However, I really do not think "use QFE" is the lesson that anyone should take away from it. This bit :

Sooty25 wrote: "Bugger! I'm not going round". Full flap, side slip. Over the fence a bit high and fast.


Is the bit everyone should be reading and learning from....just in case the last sentence of your post wasnt satire or recognised as such by some of our newer students to the forum

Regards, SD..

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 11:11 am
by T6Harvard
rdfb wrote:
Sooty25 wrote:Whilst the whole flight was one full of errors (all mine), QFE, would have prevented the workload induced one that nearly bent the aeroplane.


Snip 》
In a parallel world where everyone flies on QNH and QFE isn't a thing, I don't think you would have done that, because you wouldn't have had that habit. You wouldn't ever have to calculate circuit altitude, since that'd always be published directly as an altitude (eg. see the US). 《


Two things:

Firstly thanks to @Sooty25 for the recounting. That's how I learn best, hearing true life examples of what happened and why.

Secondly, I must admit the logic of seeing circuit height published as QNH and using only QNH seems the safest bet......

...... More popcorn anyone? :lol:

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 11:32 am
by Sooty25
@skydriller the whole flight was a catalogue of errors and were we to start analysing it, and trust me when you've nearly put your mates aeroplane through a fence you do analyse it, we will be here all day!

Human factors.

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 12:00 pm
by akg1486
Sooty25 wrote:"Bugger! I'm not going round".



Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 12:01 pm
by rdfb
T6Harvard wrote:eight published as QNH and using only QNH seems the safest bet......


Swinging the other way, since smaller GA aerodromes do always pass you the QFE if you're inbound and you have to specifically ask for a QNH, and since these aerodromes publish circuit heights and not altitudes, only using the QNH is also a pain. But it's the opposite at a bigger aerodrome where you'll be given a QNH and have to ask for the QFE. The mix of the two methods is what causes the mess, and unfortunately there's no avoiding the mess and related possible errors if you're a mere pilot.

Unless "defaulting to" QFE is forcibly abolished - for example by banning A/G and ATS from providing it except when specifically requested. Seems unlikely.

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 12:03 pm
by Miscellaneous
Sooty25 wrote:Human factors.

Indeed. And there is no one, or organisation, immune. :(

Ayone recall the F16 fatality not so long ago where an inexperience pilot was out on an exercise he had never been on and had to refuel whilst airborne for the first time, all at night? Failed to refuel, came back worked up, hit the approach antenna busting his landing gear. Flew around whilst those on the ground checked procedures, they decided not to call the Lockhead Martin engineers (it's likely they would have recommneded not landing it), deciding to land it using an arrester cable. He missed the cable, failed to go around, pulled the handle and was ejected, chute failed and he was killed. Replacement of the seat had been postponed, I think several times?

Is the thread maybe getting a little off topic for the student forum? :?

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 3:07 pm
by Paul_Sengupta
rdfb wrote:In a parallel world where everyone flies on QNH and QFE isn't a thing, I don't think you would have done that, because you wouldn't have had that habit. You wouldn't ever have to calculate circuit altitude, since that'd always be published directly as an altitude (eg. see the US).


Though you might have done this. He got the airfield elevation wrong, or did the maths wrong in his head, started the manoeuvre too low.


Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 3:15 pm
by low&slow
rdfb wrote:Swinging the other way, since smaller GA aerodromes do always pass you the QFE if you're inbound and you have to specifically ask for a QNH . . .

Or you can continue to use the QNH you were using before calling the airfield. You're unlikely to be more than 100' out.

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 4:41 pm
by A4 Pacific
Sooty

It’s probably not fair to single anyone out. We’ve all had bad days! However even the sketchy outline of your flight reads like an accident report from start to finish. So many alarm bells ringing long before you even commenced your approach. A day like that could have included ‘mis set QFE’ just as easily as double adding the airfield elevation. The resultant approach would have been identical.

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 5:17 pm
by JAFO
@iantruckers - I told you that you'd need popcorn.

I hope that you got your answer pretty early on and can now just enjoy the show. :thumright:

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Tue Jan 12, 2021 6:36 pm
by malcolmfrost
low&slow wrote:
rdfb wrote:Swinging the other way, since smaller GA aerodromes do always pass you the QFE if you're inbound and you have to specifically ask for a QNH . . .

Or you can continue to use the QNH you were using before calling the airfield. You're unlikely to be more than 100' out.

Unless it was the RPS! :twisted:

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Wed Jan 13, 2021 2:43 am
by riverrock
rdfb wrote:since smaller GA aerodromes do always pass you the QFE

Most airports that handle small GA do. Certainly those I frequent do ( Prestwick does).

Re: Why QNH when coming into an airport and not QFE?

PostPosted:Thu Jan 14, 2021 8:33 am
by Sooty25
A4 Pacific wrote:Sooty

It’s probably not fair to single anyone out. We’ve all had bad days! However even the sketchy outline of your flight reads like an accident report from start to finish. So many alarm bells ringing long before you even commenced your approach. A day like that could have included ‘mis set QFE’ just as easily as double adding the airfield elevation. The resultant approach would have been identical.


Like I said, I know it was a catalogue of errors and it doesn't need analysing. The point I was making is, with QFE your only errors are
    not hearing it correctly
    Not dialing it in correctly

Assuming you get that right, zero means wheels on the ground, and an altimeter is actually indicating height above ground in the circuit That is such a simple concept.

I know where my error was, I know why it happened, if @iantruckers takes from this that some idiot on the forum once suggested "double check your maths" that's all that I want. We can discuss the rest, including the missing bits another time.