Misuse/Misquote of QNE

[Glamdring]

My understanding of QNE is what is stated in the UK Mats Part 1...

During conditions of exceptionally low atmospheric pressure it is not possible to set QFE or QNH on some aircraft altimeters. In these circumstances an aerodrome or runway QNE can be requested. The QNE is the reading in feet on an altimeter with the sub-scale set to 1013.2 hPa when the aircraft is at aerodrome or touchdown elevation.

This is backed up by the Wiki page which lists all of the Q-Codes and their meaning, which lists QNE as...

What indication will my altimeter give on landing at ____ (place) at ____ hours, my sub-scale being set to 1013.2 millibars (29.92 inches)?

After some recent conversations and after a few Google searches it would appear that there is an alternative definition where QNE is a way of referring to the Standard Pressure Setting. This appears to be widely accepted and is actually taught to US Pilots and is listed in the FAA manuals with this definition.

This makes no sense to me, lol. Why would SPS require a Q-Code when it never changes?

Is this a common thing? Is it a US/UK thing? or a US/Rest of the World thing? What do you all think QNE is? Is there not a safety concern with different agencies having different definitions for the same term?

[FlightDetent]

What does the Definitions section of ICAO Annex 10 say about the meaning?

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Oh well, apparently nothing at all. Nor found it in Annex 3 and PANS-ATM. :confused:

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Doc 8400 also no luck.

[Sepp]

Try Combined Communications Electronics Board (CCEB) doc. ACP-131, which is the controlling document for Q- and Z- codes; they certainly used to be (1990s) repeated in ICAO 8400-4, and, iirc, 6100... I haven't had cause to check for a loooong while.



A 2009 copy of ACP-131(F) can be found here (https://web.archive.org/web/20130215140321/http://jcs.dtic.mil/j6/cceb/acps/acp131/ACP131F09.pdf). Q- codes are in Chap. 2, Sec. A. QNE is defined on p. 2-20.



One suspects that the erroneous use was once taught by person A, who taught person B .... etc. until person N wrote a manual and it became a thing.

[FlightDetent]

My 2010 edition of 8400 has about a dozen Q codes explained, QNE ain't one of them.

[megan]

The 1960 edition of MO 630 (AP 3340) Air Ministry Meteorological Office "Handbook of Aviation Meteorology" list the following Q codes relating to barometric pressure.

QFE: barometric pressure at the level of an aerodrome
QFF: barometric pressure at a stated place, reduced to mean sea level
QNH: the pressure setting which causes the altimiter to read the height above mean sea level of the touchdown on landing, plus the height of the altimeter above ground
QNE: the height indicated on landing at an aerodrome when the altimeter sub scale is set to 1013.2 millibars (29.92 inches)

The relevant chapter also notes "If with the altimeter set to 1013.2 millibars, the pilot requests QNE, the reply states what height the altimeter will read on landing at the aerodrome concerned. This is simply the height in the standard atmosphere corresponding with the pressure QFE. The use of QNE was introduced as a substitute for QFE at high level aerodromes to cover occasions when the sub scale did not have sufficient range to set QFE. With the introduction of an extended subscale and the use of alternative settings, QNE is now obsolescent"

[mustafagander]

I've always understood that QNE means flight levels.
This discussion seems to reinforce that but with a couple of add-ons.

[FlightDetent]

False impression, to my opinion.

The discussion and final link seem to reinforce its meaning of airfield elevation referenced to 1013.25.

[Dont Hang Up]

It does not seem to me to be any real source of confusion. Certainly not one that could have safety implications. Simply a matter of context.

1013.25mb is the pressure at mean sea level of a standard atmosphere.
QNE (of an airfield) is the altitude of the airfield relative to the standard atmosphere.
Flight Level is any altitude quoted relative to the standard atmosphere.
An altimeter must be set for QNE (i.e. set to 1013) in order to fly a Flight Level or fly an airfield pattern when required to fly relative to that airfield's QNE.


It seems improbable that an aircraft requesting an airfield QNE could possibly be considered to be requesting a pressure setting (which never changes) so I do not see how confusion could arise.

Although if the answer came back as 1013 it may give the commander pause for thought ;-)

[megan]

The FAA defines QNE as,QNE- The barometric pressure used for the standard altimeter setting (29.92 inches Hg.)https://www.faa.gov/air_traffic/publications/atpubs/pcg_html/glossary-q.html

More here at Section 5 of the air traffic control procedures and phraseology .

https://www.faa.gov/documentLibrary/media/Order/7110.65Y.pdf

[FlightDetent]

Full circle to the OP then?

Nice slip two posts above saying it's all clear, explaining QNE is an elevation but then telling to set it on altimeter (sub-scale). :E
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[Dont Hang Up]

Nice slip two posts above saying it's all clear, explaining QNE is an elevation but then telling to set it on altimeter (sub-scale). :E
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Er, hardly. Simply pointing out that it is an issue of context.

If you ask an airfield for its QNE you will be given an elevation. To fly relative to that elevation you will set your altimeter for QNE.

To say there are two definitions of the same term is just pedantry. To say these two definitions are conflicting is just plain wrong.

[FlightDetent]

If you ask an airfield for its QNE you will be given an elevation. To fly relative to that elevation you will set your altimeter for QNEAdmitting now this was not easy. Seeing how you set an elevation value into the collsman window. Because I imagined an airborne craft calling in.

What you had in mind, respectfully, is someone on the ground dialling the knob until the readout matches the reported value.

If this bright person happens to have his calibrated altimeter exactly on the isobaric surface as the aerodrome reference point, he would then see 1013.25 / STD / 29.92 / 760 on the sub-scale. That's why all and either of these values are also called QNE.

Couldn't be less confusing, :)
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[Gne]

On page 207 of my copy of the 1931 Edition of International Code of Signals (price 15s 0p Net then but cost me 25 quid when I purchased it from the National Maritime museum some years later) defines QNE as "Why are you Not". See attached.

There is a note saying "any misprints or other errors discovered in the code should be reported to the Board of Trade, London, as soon as possible." Anyone got the email address for them?

Gne (Qne's older brother)

[Dont Hang Up]

What you had in mind, respectfully, is someone on the ground dialling the knob until the readout matches the reported value.


In my experience that was generally how it was done at the airfield..
Dial for 0 feet and quote the QFE baro setting or dial for 1013mb and quote the QNE elevation.

Due allowance made for the height of the tower altimeter above the runway in both cases.


Couldn't be less confusing, :)
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Well it seems simple enough to me. Had no idea I was a genius!

[megan]

QNE is not so much a pressure setting but a height. If I asked you for your QNE I'm asking you for your height referenced to 1013.2 (29.92). The Q codes were introduced as short hand in the days when comms were by means of morse.