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Qnh???

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Old 24th Jul 2004, 01:08
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Grrr Qnh???

Having a debate with a mate over QNH,

Do the letters QNH stand for something, or do they stand for nothing at all?

Look forward to your responses,

WTSPT
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Old 24th Jul 2004, 01:19
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I found this out the other day - supposedly Q (atmospheric pressure) at Nautical Height.

But I always thought Q was dynamic pressure
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Old 24th Jul 2004, 01:21
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Heres one theory:

http://www.free-definition.com/Q-code.html
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Old 24th Jul 2004, 01:37
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Q code dates back to morse and was a set of 3 letter groups for ease/speed of transmission and reception.

Some, QFE QNH QDM QDR are still in use others have ceased to be used

Altimeter reads altitude or height above measn sea level with QNH set so I found Nautical Height was a good way of helping students remember which altimeter setting was which. Most light aircraft here operate in the circuit on QFE, reads 0 on the runway
so Field Elevation.

An old guy that I used to fly with came out with QBF he told me this meant " I have just entered cloud" he remembered it as Bl**dy Fool, he was flying Tiger Moths at the time
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Old 24th Jul 2004, 03:21
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Thank you all, now i have some ammunition to return with. It has certainly clarified my original understanding, that it stemmed from an old world war 2 code, now i have some evidence to support it.

Cheers

WTSPT
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Old 24th Jul 2004, 05:36
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I was always led to believe it stood for: Question Normal Height.

'QNH' was transmitted to the airfield in morsecode to get the QNH replied back to them.
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Old 24th Jul 2004, 05:51
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WTSPT,
Do a search for ACP-131. If you can find the document online it gives a complete listing of both Q and Z operating signals.

I too have been told from a number of different sources that QNH and QFE stand for "question nautical height" and "question field elevation" respectively. The only problem I have with this theory is that as 4screwaircrew pointed out, these signals go back to the days of morse code and were used to provide brevity of transmission. Now if you were asking the question ie, What is the QNH then the morse code would be intQNH, that's how it would have been done in the military anyway. So that sort of contradicts the theory that the Q in the operating signal means "question". To follow that logic then every Q code operating signal means to question.

I think to come up with the DS solution you would have to find the crusty old military signals people who wrote these things up back in the days of valve operated, pedal powered radios.

Just as an aside, for anyone who has operated military radio eqpt. I have always been confused by the designator AN as in AN-GRC106. We were always taught that the AN stood for Army Navy (yet the airforce used the same kit). About 12 or so yrs ago I read a document out of the Army School of Signals that said the AN did not mean Army Navy but was a prefix given to all US manufactured communcations eqpt. Can anyone confirm or deny this one?
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Old 24th Jul 2004, 06:51
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G'day IJ,

In Balcome (spelling? too long ago.....) on an OKR course, they said it was Army / Navy, but the AN part was an American designation. Perhaps the US Airforce didn't use them?

So where did you use a Gurk 106?



Snooze
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Old 24th Jul 2004, 10:05
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G'day Capt Snooze,

That's another reason I doubt the "Army Navy" description of the designators. With specific aircraft radios they have the prefix to their designation, ie AN-ARC***

I know the PRC is Portable Radio Communicator, GRC is Ground etc and ARC is Aircraft. So the question goes begging why would you call a radio Army Navy when it is clearly designed for any of the services. I tend to like the eplanation of the AN being a US designation, just as ours was generally F as in the F1 radio.

You certainly go back further than me in RASigs. I did my Op Kbd course in 80 and Op Rad in 82 at Watsonia. An establishment run by some of the most uptight individuals ever to don khaki.
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Old 24th Jul 2004, 11:00
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Cool

Islander Jock,

Given that the USAF didn't come into existence until after WW2, it seems likely that AN meaning Army Navy would cover the American military arrangements until quite recently. By then, I imagine it had become enshrined as the military designator for aviation communications equipment.

Stay Alive,
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Old 24th Jul 2004, 12:35
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Hi IJ

Balcombe (looked it up ) '67/'68 OKR course.

2 Sig '68/'69 Light Radio

Nasho........




Snooze
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Old 24th Jul 2004, 13:26
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Fair cop dogs,

But then the logical question goes begging... Did they use the designator AN***- pre WWII?

Most of the gear I used wasn't quite that old although it sometimes seemed the case.

Cheers

IJ

Snooze,
we had a good Q code for the crap morsies in the unit QSS.. Quit Sending ****e!
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Old 25th Jul 2004, 01:52
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Hi IJ,

QSS would have fitted me. Close as you can get to morse deaf and still pass the course!

Still remember driving off base for a w/e leave, and letting loose with a good old fashioned Golf Foxtrot on the horn........



Snooze

(getting slightly off-topic and non-aviation here)
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Old 25th Jul 2004, 03:57
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When I did my Oz army ECN radio course we were told 'AN' stands for 'complete equipment'. Christ know's how 'AN' got derived from the meaning.
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Old 25th Jul 2004, 07:18
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Q for question, NH for "Nil Hieght" ie at sea level.

An old tradition that has remained with us from the days of morse code.
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Old 25th Jul 2004, 08:22
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Reference: COMMUNICATIONS INSTRUCTIONS
OPERATING SIGNALS
ACP-131

QNH

SIGNAL QUESTION
What should I set on the sub-scale of my
altimeter so that the instrument would
indicate my elevation if I were on the
ground at your station?

ANSWER, ADVICE OR ORDER
If you set the sub-scale of your altimeter to
read...millibars (or hundredths of a inch*), the
instrument would indicate your elevation if
you were on the ground at my station
at...hours.
Note: When the setting is given in
hundredths of an inch the abbreviation "INS"
is used to identify the units.

Sorry 8/8ths, I don't go with the Q= Question theory. These codes were designed for use with CW and TTY in which case the operating signal was preceded by the prosign INT when the question was being asked.

Perhaps the NH portion of the signal does refer to "nil height or nautical height" as previously suggested. Whether this was the intent of the authors of the code or mere coincidence remains one of the great mysteries. My money's on the latter.

Last edited by Islander Jock; 25th Jul 2004 at 08:33.
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Old 26th Jul 2004, 00:35
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Q Codes

Those of you who are alert will have noticed that my Pprune nic comes from the international aviation Q code, so take it from someone who knows.

Islander Jock 4Screwaircrew are correct. The Q code was developed by the ITU around the turn of the century to standardise morse code communications and understanding between different nationalities, particularly when Morse Code started to replace Semaphore as the prime means of communications in the maritime environment. The secondary purpose of the Q code was also to abbreviate routine but long worded communications as Islander Jock has also correctly demonstrated.

I've never heard of the "Question Normal Height" theory, so I don't think that is right, although some Q codes become obvious after a while eg QFE (request "field elevation" pressure).

Along with QNH (sea level pressure), other codes that were most often used for aviation were QDR or QTE (request DF), QDM (DF inbound course), QNE (flight level based on 1013 HPa), QFE (aerodrome pressure), QTK (request GS), QRK/QSA (how do you read), QSY (freq change) etc. For example, if an aircraft wanted to know when to change frequency, it would send "QSY?' in morse. The ATS unit would respond by sending back in Morse Code "QSY125.6" or just simply "QSY" (if the unit believed the pilot already knew the frequency) which was both an acknowledgement of the aircraft's request (the pilots didn't do the communicating in those days) and approval to change. The full list of aviation Q codes can be found at http://www.kloth.net/radio/qcodes.php

Radio telegraphy (RTG) was used extensively for aviation communications in Australia and overseas right up to the late 1940s and early 1950s, and many of Australia's old Flight Service (Aeradio) Units only ever communicated with aircraft using Morse Code. In fact Cocos Island FSU was still using Morse Code for the relaying of weather, flight plans etc between Perth and Mauritius even as late as the 1980s. I also believe that the NZ Airforce were still training their radio operators on HS748s to use RTG on international HF frequencies also up to the mid-1980s. If you want to know more about this aspect of aviation history please visit the Australian Civil Aviation Historical Society website located at:http://www.airwaysmuseum.com/

Other informal codes which one also comes across today (sometimes in SMS messages) also are hangovers from MC days eg CUL (see you later); R (Regards).

Last edited by QSK?; 26th Jul 2004 at 00:49.
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Old 26th Jul 2004, 11:07
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Question Nil Height is wot me knows.

Meaning how many mm(old scale) would it be at sea level?
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Old 27th Jul 2004, 00:42
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The original question was "Do the letters QNH stand for something, or do they stand for nothing at all?"

Agreeing with everything QSK has posted (feel free to break in on my transmissions anytime mate), I understand it (in itself) means nothing at all. It is a code group. The "normal height" thing is just a mnemonic somebody has used to learn it, and passed on. For generations.

It is no more an acronym for "normal height" than S0S is an acronym for "save our souls". SOS just sounds distinctive in morse and somebody has used "save our souls" for the incredible task of learning the meaning of SOS. Like PAN.

I may change my name to QKF NOW PLEASE.
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Old 27th Jul 2004, 01:00
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Spodman:

I'm guessing you probably started work at 0600, so you can QKF1312 (or do you guys now work 8 hours instead of the old 7 hours and 12 minutes?).

For info, I settled on my Pprune moniker when I started replying to Dick Smith's diatribes re NAS on these fora; and noticed that he was never off the old PTT.

I was hoping that he would recognise my nic as being from the Q Code and then look up the code up to ascertain its hidden meaning. Unfortunately, no such luck.

Cheers QSK?
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