Qnh???

[WTSPT]

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:ok:

[ROB-x38]

I found this out the other day - supposedly Q (atmospheric pressure) at Nautical Height.

But I always thought Q was dynamic pressure :confused:

[grrowler]

Heres one theory:

http://www.free-definition.com/Q-code.html

[4Screwaircrew]

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;)

[WTSPT]

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;)

[VRB03KT CAVOK]

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.

[Islander Jock]

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?

[Capt Snooze]

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

[Islander Jock]

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.:ugh:

[4dogs]

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,

[Capt Snooze]

Hi IJ

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

2 Sig '68/'69 Light Radio

Nasho........




Snooze

[Islander Jock]

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!:p

[Capt Snooze]

Hi IJ,

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

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)

[Tinstaafl]

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.

[8 8th's Blue]

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.

[Islander Jock]

Reference: COMMUNICATIONS INSTRUCTIONS
OPERATING SIGNALS
ACP-131 (http://www.dtic.mil/jcs/j6/cceb/acps/Acp131.pdf)

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.

[QSK?]

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).

[DownDraught]

Question Nil Height is wot me knows.

Meaning how many mm(old scale) would it be at sea level?

[Spodman]

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.

[QSK?]

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?

[Bill Smith]

The Q code is a set of three-letter code signals to be used in radiotelegraphy and amateur radio communications. It was developed and instituted in 1912 as a way to facilitate communication between maritime radio operators of different nationalities. For this reason, callsigns never begin with a Q.

Used in their formal "question/answer" sense, their meaning varies depending on whether they are sent as a question or an answer. For example, the message "QRP?" means "Shall I decrease transmitter power?", and a reply of "QRP" means "Yes, decrease your transmitter power". This structured use of Q codes is fairly rare and now mainly limited to amateur radio and military CW traffic networks.

Many militaries and other organizations that use the morse code have their own code they use besides the Q code, such as the Z code that is in use in most European and NATO countries. The Z code contains many commands and questions that are needed in military radio transmissions, that weren't included in the Q codes, such as ZBW 2 (change to backup frequency nr. 2) or ZNB abc (my checksum is abc, what is yours).

For instance, in most military morse code transmissions, any freeform text is strictly forbidden and all communications must be accomplished by the use of three-letter acronyms, the Q and Z code.

In modern everyday amateur radio practice, the Q codes are more commonly used as shorthand nouns, verbs, or adjectives. For example, one will sometimes hear a ham complaining about QRM or telling another ham that he "has QSB on his signal"; if a ham wants you to change your operating frequency, she will ask you to QSY. Although the Q codes were created for use during Morse code operation, they are now commonly used in voice modes too. The following table gives the most common Q codes used in the amateur service, along with their meaning and sample use.

ICAO PANS Doc8400 :
The ICAO Q Code

http://www.kloth.net/radio/qcodes.php#qaa

[dogcharlietree]

Ok, we all agree that the Q Code came in around 1912. However at that time and up until the mid '40's, there were NO QN.. codes.
Question, when did the QN.. codes appear.
Up until the mid '40's, there were QA.., QB.., QC..,QD..,QF..,QG..,QR..,QS..,QT.. and QU..

[Richo]

Hi IJ hows the wife.

I have always found the term AN is used as a predesignator (prefix) for Military Electronic Equipment.

All TX and RX type units seem to have the designation. For example (from my side of the street) AN-TPS-43f which is a Westinghouse Radar. The Navy units are also AN designated.

I can't think of any non Electronic equipment that has a AN prefix.

Maybe you can, or any of the other EX Military types.

Out of curisity (QSK you seem to be ATC) do civil radars have a AN type prefix before the type designator.


My personal feel for the Q codes is as said by Bill, but I don't mind people afixing names to them (Normal Height) etc if it helps them remember it.

Richo

[Spodman]

Nice try QSK, but you can't interrupt somebody born without ears!

I remember leafing through the ICAO doc years ago and coming across a Q code for "Request a competent operator", but can't find it now. Maybe it was just a bad dream...:uhoh:

[Islander Jock]

ZBM

ANSWER, ADVICE OR ORDER
Place...on watch on this frequency.
1) A qualified speed key operator;
2) A competent operator.

ZBM2 would be the appropriate code in this case

ACP-131 has the lot!