E3D ZH101 Altimeter in Inches

[Standby!]

Can any of you aircrew answer this question? Today, I (a humble air trafficker) spoke to an E3D (as it had a UK Mil reg and was a 8/23 sqn aircraft), and although it was a Brit aircraft (albeit with a non-UK sounding pilot (exchange?)), its altimeter was in inches rather than Mb. Can any one explain? Cheers.

[maccer82]

Because it is an old american aircraft, and they like to be different...

[L J R]

....and why do RAF insist on QFE when rest of world use QNH!!!!!!!

[LateArmLive]

Because when the little hand reads zero it means you've landed?

[Confucius]

Give us the QNH/FE in mb, and we, the crew, will convert to inches.

[L J R]

Late Arm - Would that be before or after you hit the hill, entered nearby airspace or collided with someone else nearby who happens not to be landing at same airfield??

[BEagle]

If it has an altimeter with an electronic subscale the subscale decrements in discrete steps, rather than continuously as did older clockwork altimeters.(e.g. as in the Vickers FunBus - 3 clicks per millibar if I recall correctly - or alternatively in precise 0.01 inch Hg intervals as it had both options).

Given the relatively coarse assessment of touchdown zone QFE at most military bases (usually derived from standard correction applied to a value obtained from the Met Office up to an hour aga, the error displayed at the threshold using QFE may well put an RVSM-compliant altimeter out of limits if mB are used, whereas with precise inch Hg values, the greater precision may put it inside limits as you have 1, not 3 subscale alternatives.

The solution is to have instantaneous exact QNH inch Hg values available, plus accurately surveyed parking position elevations. So that you can check whether or not your altimeter is really within limits. But that would cost monry, so just fudge it and hope - as with most military compliance with current rest-of-the-world requirements.

[Confucius]

Oh, it reads in inches because the E-3 was bought at short notice pretty much 'off the shelf' following the AEW Nimrod fiasco. Unlike so many other US (as opposed to U/S that is) bits of kit, 'we' didn't have time to meddle with it, at great expense, to convert to UK standard.

Sadly, many, if not most, E-3 crew don't perform their own conversions.

Not so much in the UK, but certainly in europe, I've had many an air traffic agency convert mb to inches incorrectly. I have seen E-3 crews accept an incorrect a/t figure rather than trust the conversion out of the FIH. W@nkers.

[BEagle]

When I was struggling to get through the Buccaneer OCU at Honington back in 1976-77, we were told one day about an incident which had happened the previous night involving one of Uncle Spam's finest going into Mildenhall. He had been passed nine-nine-something as the 'altimeter' setting and had set it as twenty nine-point-nine something inches. As a result, he was hundreds of feet too low and I'd actually heard him going past Honington very low indeed...

We were told that, had Mildenhall been on the other RW, he would probably have hit the ground.

Of course this was long before radar altimeters and GPWS were fitted to all military heavies......wasn't it :rolleyes: ?

[neilmac]

Maybe it was a Foreign E3D working in our airspace tasked by UK though ??????? thought that would be the easy answer?

[maccer82]

...and the UK Mil reg?

[Busta]

1. This has happened before, F4J subscale was inches; I roamed around uk and yurap '84 to '88 and got inches on request (used to know a girl like that!).

2. Landing on QNH is not natural, you have to do sums.

nothing matters very much, most things don't matter at all.

[ORAC]

Foreign E3D????? :confused:

[Pie Man]

The French E-3 uses mbs.

PM

[Pontius Navigator]

LJR - no, the rest of the world does not use QNH.

In UK Civil Aviation uses QFE for instrument approaches if I remember correctly.

As far as trying QNH, at great expense Lady Belinda Buck's lover introduced QNH in the RAF and we had to try it.

Once his flies failed we then reverted to QFE.

One the inches/mb question, on the Vulcan the rule was quite simple. If an American controller, being helpful, gave a setting in Millibars we had to ask for it in inches and then two of the crew would convert it to millibars.

Now we use hectopascals I guess it may all be different.:)

[k3k3]

On Nato E3As (which have the altimeter baro scale in InHg) there is a conversion chart InHg to mb/HPa on the grey plastic between the pilots windscreen and the eyebrow windows, fixed with clear sticky back plastic in the best of Blue Peter traditons.

[Green Flash]

Post cold war, when the first of the Migs, tupolevs etc etc started drifting over, there was also mm of mercury. Mb's, Inches, Mercury!!! Aarggh!!:\

[spekesoftly]

In UK Civil Aviation uses QFE for instrument approaches if I remember correctly.

In years gone by, yes, but the vast majority of UK civil commercial flights now use QNH for instrument approaches. (I can't readily think of any UK Airline that still uses QFE).

BEagle's 'Mildenhall' incident, and others tales of mb/inch confusion, reinforce the need to specify "millibars", especially when the pressure is less than 1000 mb. Guidance in CAP 493 requires that UK civil ATCOs do so.

[trilander]

I used to instruct for a popular IR training school and the good chaps at CAAFU would accept a candidate givig DH in qfe or qnh, ant an alt in mb or inchs.

[False Capture]

Bet you military boys don't use QFE when landing at high altitude airfields such as Denver, Nairobi, Jo'burg, etc.:eek:

[Foxthreekill]

I have seen E-3 crews accept an incorrect a/t figure rather than trust the conversion out of the FIH. W@nkers.
I see from your profile Confucius that you clearly didn't do too well at school yourself. Stones in glass houses etc....

[Pontius Navigator]

False Capture, quite right QNH at high airfields.

[Crashed&Burned]

Modern civvy light aircraft have both an inches and a mb scale for the altimeters.

C&B

[Ginseng]

Further to your post quoted by F3K:

The conversion table in the FIH would never, of course, be wrong would it? Err ..... Oh dear, yes it was, just last year. A replacement table had to be published in the Amendment Bulletin, I recall.

W@nker.

Regards

Ginseng

[Foxthreekill]

Ginseng.
My thanks.

F3K

[Out Of Trim]

Or - You could memorise them!

from memory 1016mb - 30.00 inches / 1015mb - 29.97 inches etc,etc.

[maccer82]

Isn't the millibar now the hectopascal? Same measurement but different name...

[NutherA2]

:ok: QNH at high airfields

And even at some not really high ones during severe depressions (met, that is, not crew). I remember a few occasions at Perth in the 70s & 80s when MSL pressure was so low that the millibar sub scale wouldn't wind down enough for us to set QFE. We used QNH although I believe there was an extremely involved alternative involving 1013 (QNE?) and performing advanced mental arithmetic.:sad:

[Confucius]

Further to your post quoted by F3K:
The conversion table in the FIH would never, of course, be wrong would it? Err ..... Oh dear, yes it was, just last year. A replacement table had to be published in the Amendment Bulletin, I recall.
W@nker.
Regards
Ginseng

The current one is correct W@nker.

There are other conversion tables too, didn't teacher tell you?

Retire whilst the going is good old man.

[Confucius]

Ginseng.
My thanks.
F3K
Ah, a fast jet w@nker. At least in a '16 you'll be the only one dead when you crash with an incorrect altimeter setting (if you ever make it out of the 'States, that is.)

[False Capture]

At least in a '16 you'll be the only one dead when you crash...Unless it's an F-16D....:}

[Brain Potter]

As their airships appetite is for all things expeditionary we ought to simply adopt the practice employed by the vast majority of the avation world- QNH. Surely now that everybody has had more exposure to deployed ops we could ditch this parochial QFE nonsense? Train like we fight etc.. I heard that the main resistance to coming into line with everyone else is from PTC/CFS. Tail wagging dog again?

[Pierre Argh]

Latearmlive says (of using QFE)Because when the little hand reads zero it means you've landed? ...'ish; give or take 20ft!!! (thinks maybe that explains some of those heavy landings I've seen recently)

[vigilant_spacey]

LJR

QFE is used by GA traffic for take off and landing, and QNH whilst operating in a region. I don't fancy landing on QNH, and on touch down seeing the altimeter reading below zero!

Vigi

[Roland Pulfrew]

As their airships appetite is for all things expeditionary we ought to simply adopt the practice employed by the vast majority of the avation world- QNH. Surely now that everybody has had more exposure to deployed ops we could ditch this parochial QFE nonsense? Train like we fight etc.. I heard that the main resistance to coming into line with everyone else is from PTC/CFS. Tail wagging dog again?

Brain

Having been through the QFE/QNH fiasco in the 90s, I think it is far more sensible to train student pilots on QFE. Much less maths involved. Used to enjoy watching baby pilots from low lying airfields trying to do PFLs etc at relatively high airfields (nothing as high as Nairobbery) and waiting for the thinks bubble that 2500 ft QNH is a bit different from 2500 ft QFE and they are now too low for a successful PFL. IIRC we almost lost a Tucano(?) following the QFE/QNH fiasco, he overshot at 20 ft IMC due to the difference. 0 for touchdown in the UK where the highest airfield is Leeds(?), much easier.:ok:

[Foxthreekill]

ConfuciusAh, a fast jet w@nker. At least in a '16 you'll be the only one dead when you crash with an incorrect altimeter setting (if you ever make it out of the 'States, that is.)
Actually in 19 years I've done allright, spent 3 years on exchange with the RAF and traveled the world from Korea to Germany, and various sandy places in between... and all without a Nav. Also I've managed to do without feeling the need to sling sh1t people I've never met, for no reason, and end up looking like a bitter and twisted Fcukwit.
F3K

[Ginseng]

Whoa! Is that "old man" in an ever-so-polite Upper-Middle-Class British kind of way, or "old man" in a derogatory way?

Seriously for a moment, what was really the point of your first post? The person who started this thread asked a simple question about why an E3D crew had asked for the altimeter setting in inches of mercury, to which there was a simple answer. You, however, seemed to see it as a heaven sent opportunity to sling mud (unjustifiably, I would presume) at a fleet which, for some reason best known to yourself, you obviously hold in low esteem. You quite unnecessarily signed off with a derogatory comment, which, when handed back to you, you clearly didn't like. Has there been a spate of E3 crews throwing themselves into the ground with the wrong QFE/QNH set, that I haven't heard about? No, I thought not.

Among the benefits of a forum like this is the opportunity to say what you really think; without fear or favour, without the need to be deferrent to rank, without fear of falling out with people you know and respect. I believe that benefits us all. It is rather like having an anonymous version of the good old crewroom discussion, except that you can reach far more people here than you will find in the average crewroom these days. Old fogies like me can blether on without subjecting sharp young blades like yourself to the smell of wee, which is much more pleasant for you and much less embarrassing for us.

For that privilege, I think it best not to hand out insults if you can't take them back. Moreover, I don't think insulting our transatlantic guests here is fair game. It quite spoils the aura of the British stiff upper lip, don't y'know!

Oh, and I'm not quite ready to retire just yet thanks.

Now, shall we call it an honourable draw?

Regards

Ginseng

[Brain Potter]

RP,

At the time of the last QFE/QNH debate I was firmly on the side of the QFE advocates as I had never operated outside the UK. However we now operate all our front line ac types all round the world (often at high elev). Would it not be wise to bite the bullet and change to the system that everyone else uses? A brand new student who has never seen QFE would just accept that the airfield is 200ft amsl and that the circuit is flown at 1200' QNH. How do other air forces cope? It may be easier to use QFE to teach aerodrome procedures in the flatlands of Lincs but that comes at the expense of terrain and altitude awareness. I accept your example, but the same student has to be capable of PFL'ing into a field on the Regional QNH. Would he not be more terrain aware if the false principle that altimeter always reads zero on the ground had not been introduced from trip 1?
At multi-engine OCU level I have seen poor SA from students who are not used to operating on QNH. Nearly every training approach they make will be on QFE at an RAF airfield and most of their for-real approaches will be on QNH at a civil airport or foreign military base. Additionally as more civil charter aircaft use our bases we are faced with mixed QFE/QNH ops - which is not ideal.
I believe that we should be making it as easy as possible to operate safely when everything else is strange and consequently we are doing ourselves a disservice by persisting with this eccentric and anachronistic practice.
I think that most ME types woyuld prefer to have one procedure (which would have to be QNH) and I would be interested to hear if the views of FJ/RW folks have swung towards QNH now that they are operating in "stranger" areas more regularly?

Interesting debate though :)

[L J R]

For us slightly hard of seeing, the QNH values on the TAPs (The ones in BOLD) are more easy to see than the not-so-highlighted HAT/HAA figures.


You want more reasons??




Vigilant Spacey, When you operate from your GA airfield with QFE, how far above you is the 'local' airway, and at what point approaching the airfield does your buddy who is arriving set the QFE in order to determine how much separation he/she has with you while you are going around from the base turn point?.


If you really want to know how high off the ground you are in the flare - get a Rad-Alt!

[SASless]

BP,

It is a British thing you know old bean, and if it was good enough for Wellington then by gosh....who are we to change something just because the entire rest of the world is doing it?

[Standby!]

Thanks to the person who supllied a response to my simple question! I can't believe it led to all this! I think this draws this thread to a close. Cheers!

[L J R]

no it's not.

[Two's in]

When there was a change or trial use of QNH in the zone in Germany in the early nineties (the exact details of which escape me) it was definitely confusing for both the controllers and the pilots to get QNH readback and then be given a confirmatory QFE. It really is what you are used to I suppose, but it is an obvious "Gotcha" waiting for the unwary. Having started the QFE way, but now being used to QNH, the latter does seems more logical (it also makes sure you get the aerodrome charts out and check the elevation every time). Mind you, being a rotary w@nker most of the time, it is largely academic when VFR.

[Pontius Navigator]

Two's In, as I said at the outset, this was no trial. The change was imposed from the very top against the strongest opposition from the pilot lobby, led by CFS and supported to some extent by the beanies.

Just think for a moment just how many documents are written around QFE. The easy ones of course were the Planning Documents but all the STARS, and every TAP plate had to be re-written and some airfields had a handful of plates.

Even before the door had stopped banging or the cleaner had polished the desk as CAS departed the process of switching bavk to QFE began. It took, if I remember rightly, rather less time to revert. I guess someone may have had a premonition and kept the QFE plates.

[4Greens]

The safety reason for using QNH is for the Go around situation and hence keeping clear of high ground and obstacles that are charted amsl.

[SASless]

4Greens,

Along with the Missed Approach....all opportunities to incorrectly set the Altimeter are reduced when using the QNH method vice the QFE/QNH method.

In the USA...transition altititude is a standard 18,000 feet and below you use the QNH and above you use Flt Levels based upon 29.92/1013 settings.

All maps and charts show Elevations of pertinent obstacles and airports with a subheight indication showing Height Above Ground for obstacles.

For my view it matters not what the altimeter indicates during an approach or at touchdown...the number is calculated for me on the approach plate thus I don't even have to do maths as someone suggested.

If one cannot remember a single number array....from one to four digits long...he has not business flying.

All this argument stems from a group of folks that refuse to accept there is a different and better way to do things. After all, it you leave Blighty and go anywhere else in the world...you will adapt to the QNH system and have to revert to the UK system when back in the UK.

[sonicstomp]

Confucius - a few things :

1. Where is your evidence about E3 crew altimeter setting procedures ? - we always convert the figure if given in mbs (no mb option available on the altimeters)

2. I have been given an incorrect setting in inches (incorrectly converted by homeplate ATC), we cross-checked and challenged it.....

3. There is currently a stop-press at Waddo indicating that the FIH conversion table is indeed incorrect (we use either the ODM (or a crib from it) or our Nav system CDU which has a conversion calculator on it)...

oh, and another thing..

4. Why the unjustified mud-slinging, and what gives??

[4Greens]

British Airways (BOAC) used to use QFE. After some near disasters including one going in to Nairobi they joined the rest of the world on QNH.