QFE info

[JammedStab]

It appears that our aircraft do have this capability but while we do not go anywhere with QFE ops, there could always be a diversion to such a place.

First of all, where can one expect to have to use QFE and second, where can I find detailed information on what procedures should be done?

Thanks

[esreverlluf]

If you do go to one of these places - ask them for a QNH. Why make things harder for yourself than they have to be. If it is not forthcoming, then it is still not that much of an issue.

[JammedStab]

Originally Posted by esreverlluf

If you do go to one of these places - ask them for a QNH. Why make things harder for yourself than they have to be. If it is not forthcoming, then it is still not that much of an issue.

Do all QFE locations have QNH available as well?

[Tu.114]

Usually, they do report a QNH on request (at least in the former USSR), but it is not necessarily correct. ATC may not always be familiar with QNH procedures and seems to calculate the value on the spot on occasion. So do take the time to calculate an expected value from the QFE and the field elevation (27ft per hPa) and check it against the number received from ATC, this might save You some headaches.

Also, for reference: 760mmHg=1013hPa; this is useful in some countries as well.

We used to employ the table on the Jeppesen charts that gave the atitudes in ft over QNH corresponding to the meters over QFE that ATC cleared us to (of course, the table was custom-made for each airfield!), thereby internally flying using ft and QNH but getting cleared by ATC on the local m/QFE system.

[autoflight]

Depending on your aircraft type and QNH/QFE mod status, altimetry procedures can be exacting, like in China. An A320 is highly dependant on correct procedure. Pressurisation, EGPWS, TCAS, EFIS etc.

[9.G]

J.S if you have the QFE option simply use it if you go to the places where altitude instructions below TL are given by the reference to QFE. No brainer there. Airbus is gonna take care of the rest. Obviously you'll need to use DH and associated approach procedures. If you elect to use QNH with QFE based altitudes then simply add the field elevation to any given height to obtain the altitude.

[Deep and fast]

There was a 747 cargo plane that got a gpws warning after asking for QNH from a controller in a QFE environment. Use QFE or do the math carefully.

We just use QFE and brief accordingly. Russia is much simpler since the adoption of RVSM.

[Wizofoz]

J.S if you have the QFE option simply use it if you go to the places where altitude instructions below TL are given by the reference to QFE. No brainer there. Airbus is gonna take care of the rest. Obviously you'll need to use DH and associated approach procedures. If you elect to use QNH with QFE based altitudes then simply add the field elevation to any given height to obtain the altitude

Careful on that. The EGPWS database in Boeings isusually based on AMSL and assumes QNH unless the aircraft is equipped accordingly.

Is the Airbus different?

[Monarch Man]

Careful on that. The EGPWS database in Boeings isusually based on AMSL and assumes QNH unless the aircraft is equipped accordingly.

The giveaway on suitably equipped Boeings is on the Approach Ref page, it gives you the option of QNH or QFE

[9.G]

Wiz, it all depends on the pin programming. Some operators only use QNH some do both. Airbus has got the option to have both QNH & QFE thus my previous post. I find it way easier to use the QFE option in QFE environment.

[TurningFinals]

Most military aerodromes in the UK use QFE.

[autoflight]

My A320 operations into China without the QFE option, though possible with care, should have been disallowed. I finally realised why I was rostered for all of those flights! This is the case where setting QFE can give EGPWS warnings on take-off or go-around if not disabled. Any higher altitude airfield where QFE is set, without the QFE option, would give the same result.

[woodja51]

QFE vs QNH options

Beware mixing the two... The fcu may have a QFE option ( they sometimes default to this on power up in the A330 for example)

This is NOT the same as the QFE pin programming on the FMS..

Which can be identified by the approach page having MDH instead of MDA ...

There are issues with the qfe programme.. not the least are issues doing fully managed approaches, or lnav vnav for Boeing dudes...

Some like the egpws isssues mentioned earlier, some like the fact that you can only type mdh values in up to 5000 feet , so how do you remedy that one into say Nairobi, Kunming or Sanaa for example?

There is a section in the FCOM about the issues...suggest you resd it closely.

And the autopilot has different disconnect points ... Which can be briefed but might be unexpected if you are not prepared.

There is also a bulletin about copying the secondary over to the primary and getting an erroneous value in the MDA/ MDH field by the elevation etc...

Overall, be very careful how you use any of these would be my advice.

In China Southern for example I asked about what they do when they go to a high alt airport ( they have QFE pinned FMGS) I was told they just use the MDA...but my answer about why not type in the MDH for lower airfields , and when would you change over was a bit vague...

In summary... The charts that convert QFE/QNH metres etc as designed for each airfield seem complicated but they would appear to be the safest I have seen...

The key there is not to have the metres button selected below transition as that can screw you up ( it just messes with your head a bit) in Russia for example... Ask emirates ..they had a few incidents with that a while ago. Lucky domodedevo is pretty flat...
MW

[9.G]

w51, there're many ways to skin the cat but I find it simpler to have the same denominator, if you wish, when working in other systems let it be metric or QFE. Historically QFE is used in the metric system, except UK RAF, thus since you're already using QFE (height) why not simply set given height in meters. You don't need brainstorming, converting etc, just set e.g. 500m on PDF, can't be that difficult, can it? Yes FCU is only ft but you're supposed to cross check the settings with PDF anyway. The metric system and QFE are two different animals but used to form the same system in the former USSR however QFE and FT were very much used in the UK. Whether you set meters or feet doesn't change the fact that one might be at the wrong height, altitude if the wrong pressure was set. The confusion comes from the fact that multiple steps are necessary to convert given metric height QFE based into FT altitude QNH based coz then you must first convert QFE given metric height into QFE ft height then add field elevation to obtain QNH alt but it's all in vain if you set QFE instead of QNH on FCU and vice versa. Why not make it simple, if QFE is used select height, if QNH is used use altitude. Doing so you'll always have the same denominator whether you set meters or feet or inches etc.

[Zoner]

Quote:
"If you do go to one of these places - ask them for a QNH. Why make things harder for yourself than they have to be. If it is not forthcoming, then it is still not that much of an issue."

Be careful what you ask for. In Bishkek asking for QNH will get you the QNH altimeter setting and QFE vectoring altitudes, in Almaty it will get you QNH altimeter and QNH vectoring altitudes. Best to stay with company SOPs.

[TurningFinals]

Out of interest, why would you not want to use QFE? Surely your altimeter reading 0 on the runway makes things easier?

[bubbers44]

Because 90% of the world doesnt use QFE. We did at AA a while back and saw a lot of major FU's by very experienced pilots setting every altimiter to QFE and would have busted altitudes if I had not said you have our primary altimiter set to
QFE. It was a stupid procedure and they changed it. Thank God. Why make something simple complicated?

[bubbers44]

Now the GPWS is said to go off because of the lower altitude displayed. Why not just do it like the rest of the world does? AA did it the other way until they realized how stupid it was. Now they use QNH like everybody else making life simple.

[9.G]

Zoner, FRU switched to QNH since it was turned into a USAFs hub for Agfan war. QFE is still available though. ALA has the option to give you both. You're the master of your fate there. Surely if you request QNH you'll be assigned altitudes based on that and vice versa. Now the point here was: If you have the technical option to use QFE such as pin programming and the place only runs QFE then surely you'll make your life way easier to use it provided, of course, the operator is approved and SOPs are in place.

bb44, your so-called major FU are only to be traced back to poor standardization due to lack of technical background understanding. If you don't the option to switch to QFE, of course your GPWS is gonna go off, pressurization isn't goona work, etc. It's plain simple: one is the reference datum and the other one is the selected value. If you use one reference datum and select a value based on a different one, well a major FU is inevitable.

The bottom line is: if only QNH equipped a/c then use alt with QNH. If QFE option is installed, heights and QFE can be used. It's optional and up to the operator. Don't demonise something you don't understand.

P.S. by selecting the QFE settings on EFIS control panel one simply changes the reference datum for the target altitudes. However all relevant aircraft systems such as GPWS, FMGEC, CPC etc know that you've changed the reference datum and operate normally. Surely airbus wound't design and release QFE option to the world if it was unsafe as some claim. BTW it's stricly prohibited to use QFE settings on QNH only programmed aircraft.