QNH 1000 - digit by digit or 'wun tousand'?

[jon5]

CAP413 says that altimeter pressure settings must be transmitted digit by digit, but some of the PPL texts say that 'QNH wun tousand' is OK on the radio and apparently this is due to a UK exemption.

I would have thought CAP413 would list this exception though. Anyone know the definitive answer to this (and where it is listed?!)

[loubylou]

Not sure where it's listed - possibly the RTF manual - but
Q999 = QNH niner niner niner millibars
Q1000 = QNH wun tousand (millibars)
Q1001 = QNH wun zero zero wun ( millibars)

louby

[smellysnelly2004]

Saying QNH wun tousand on a basic sim summative here at Hurn would probabaly earn you a mostly achieved for RT!!

[loubylou]

Why? If you mean without saying the word "millibars" - that's why it's in brackets as using "millibars" when issuing a QNH is a NATS standard only.
If it's another reason - can you clarify what you mean please?

louby

[Defruiter]

At Hurn, we had to say it digit by digit, because that's what the book says.

There are a lot of things we were "supposed" to say at Hurn, which as soon as you leave Hurn, you will never say like that again

[flower]

As Louby says I have always transmitted it as one thousand millibars I have never heard it transmitted as individual figures.

[GuruCube]

Personally....
I transmit it as 'wun tousand', mainly to get it across without confusion. If you start listing off the same number, in my opinion its easy for people to get confused or misinterpret. Its like callsigns of XXX5333. I generally call them 'five-triple-three' as quite often you can see 5133, 5233 etc. and it makes it much less likely to be confused with similar callsigns.

[2 sheds]

The fact of the matter is that the UK CAP413 Radiotelephony Manual and the UK MATS Part 1 used to specify that it should be transmitted as "one thousand (millibars)". Then, a few years ago (four or five?), it changed to come into line with ICAO and it is now implied that this particular value should also be pronounced in individual digits, viz "one zero zero zero (millibars)".

I wrote to CHIRP many months ago on this subject as I thought that the original UK practice was very sensible insofar as it guarded against the possible confusion of 1000 and 1010. I seem to recall that CHIRP sympathised and forwarded it to CAA SRG - and a resounding silence ever since. I would have thought that this was a safety-related issue to which they ought to apply a little more urgency.

You cannot blame the ATC colleges for teaching to the book but I do wish that they would be more proactive in flagging up such problems to CAA - they ought to be the first line of defence on procedures such as this. Mind you, how many controllers or operational units have bothered to go into writing to CAA on such matters? All the effort in typing on an internet forum could be directed to better effect!

[loubylou]

That explains that! - Didn't realise I was that old and crusty!!!
Though I think I will stick with wun tousand!!
And no problems with the college teaching book perfect - just thought my phraseology was up to date - bum!:O

louby

[jon5]

Well thats the curious thing.... the older PPL texts say QNH digit by digit, but its the latest edition that says 'wun tousand' is OK by UK exemption!

Sounds like the latest edition of the RT book has lagged (a long way) behind the older CAP413 edition that suggested the use of 'wun tousand'.

Interesting that the current state of play is digit by digit. For the reasons above this one would be more sensible as 'wun tousand' wouldnt it. And there is a precedent in FL100 versus FL110 etc.

So it sounds like the rules say digit by digit but lots of common practice goes by the alternative.

[jon5]

Good point 2sheds - so I winged SRG an email and here is what came back.

Your query has been forwarded to me for a response. The short answer is that each digit should be pronounced eg WUN ZERO ZERO ZERO.

The reference is CAP413 Chapter 2 Page 3 paragraph 1.4.2 (a) which says
that "When transmitting messages containing .....altimeter
settings.....each digit shall be transmitted separately;..."

The circumstances in which WUN TOUSAND should be used are outlined later
in the same paragraph (1.4.2 b) and do not include altimeter settings.

In practical terms, there would be a risk that if WUN TOUSAND were used
to pass an altimeter setting, this could be mistaken for all or part of
a level instruction.

I hope this answers your query. Please do not hesitate to come back to
me if you require any further clarification

[2 sheds]

What an imagination some of these people have! Which is the greater risk, mistaking it for a level instruction (and prefixed "QNH" and even, if they wished, suffixed "millibars") or reading back or writing down or setting 1010 mb in error?

I wouldn't normally indulge, but :ugh::ugh:and:ugh: !!!

2 s

[Spitoon]

Probably just a reflection of this Safety Management System culture where you have to do a risk assessment and then do something to stop that hazard occurring. It doesn't always mean that the outcome is good overall though.

[skiesfull]

When will you guys adopt the 'Johnny Foreigner' style known as Hector Pascal? -but keep away from 'inches' whatever you do!

[Tommyc81]

This is a issue that applies to more things than just the pressure. I have to admit that I'm not quite sure what the manual says but I use the following phrases to make sure it's not misunderstood:

Climb/descend to flightlevel "wun/two/tree/four hundred"
Turn left/right/fly heading "wun/two/tree hundred"
And of course: QNH "wun thousand"

Depending on pronounciation the number zero is easily mistaken for number seven. And I would definitely say that there's a bigger chance you miss a seven in a readback instead of zero (or the other way around) than missing/misunderstanding keywords such as flightlevel, heading or QNH for the number passed.

[radarman]

Tommy,
If you worked in the UK and said '..... heading tree hundred' you would be shot. But what you say may very well be standard R/T in Sweden.
Which nicely illustrates the weak point in all this effort to ensure controllers use 'standard R/T'. We each use the phrases deemed acceptable by our respective national aviation authorities, but in spite of ICAO there are numerous differences between each state's standards. So our customer - the pilot - flying on an international route, will be subjected to a number of variations on a theme and have to interpret them all accurately. What's the betting in a normal day he will hear both 'One tousand' and 'One zero zero zero'. He'll know what it means. Isn't this all getting a bit anal?

[radar707]

Tommy, in the UK when we issue a turn instruction with a heading ending in 0 we say "degrees" afterwards to avoid any confusion.

I can't see what confusion can possibly exist with the instruction:

"descend to altitude two tausand feet, QNH one tausand"

Clear, conscise and unambiguous.

What gets my goat at the moment is the number of crews flying into EGBB when cleared to: "descend to altitude two tausand fife hundred feet"

read back "Roger descend two fife zero zero feet"

For all of you doing this DON'T it sounds just like

"Roger descend TO FIFE ZERO ZERO FEET"

And I don't want you at 500ft you're not MAHAN Air!!

[Tommyc81]

Tommy,
If you worked in the UK and said '..... heading tree hundred' you would be shot. But what you say may very well be standard R/T in Sweden.

The correct phraseology according to Swedish regulations are:
Fly heading (3 digits)
Turn left/right heading (3 digits)

When the radiotransmission is good you are allowed to simplify numbers and values (wun hundred/tousand etc.) BUT headings should normally be read digit by digit. Though I personally use "wun hundred" etc. after some confusion between 100/200 and 170/270, which I haven't experienced since.

Tommy, in the UK when we issue a turn instruction with a heading ending in 0 we say "degrees" afterwards to avoid any confusion.
Only if you want an aircraft to turn a specific number of degrees in either direction you use "degrees" over here:
Turn left/right (3 digits) degrees

Which I, to avoid confusion, usually say: Turn left/right BY (3 digits)

Which nicely illustrates the weak point in all this effort to ensure controllers use 'standard R/T'. We each use the phrases deemed acceptable by our respective national aviation authorities, but in spite of ICAO there are numerous differences between each state's standards. So our customer - the pilot - flying on an international route, will be subjected to a number of variations on a theme and have to interpret them all accurately. What's the betting in a normal day he will hear both 'One tousand' and 'One zero zero zero'. He'll know what it means. Isn't this all getting a bit anal?

Good point, I really find it interesting to hear what the practice is in other countries, gives a bit more understanding about the pilots situation. Thanks!

[WestWind1950]

When will you guys adopt the 'Johnny Foreigner' style known as Hector Pascal? -but keep away from 'inches' whatever you do!

I wondered when someone would mention that! I think the expression HectoPascal (hPa) is so stupid... millibar makes so much more sense! Another area where there is NO international standardisation! :ugh:

[ITO]

I just flew yeterday with a QNH of 1000 hpa, and everybody was saying One thousand, even the big guys on the big big engines !

[Spitoon]

Another area where there is NO international standardisation! Sorry WW1950, but there is standardisation for units of measurement - it's just that there is more than one standard to choose from. Although, admittedly, sticking to mB instead of hPa does deviate from the standard.

[trafficcontrol]

yeah i agree, i have never personally heard 1-0-0-0, nor the squawk 7-0-0-0 which is CAP 413 phraseology.

If its not causing a problem or confusion, which it doesnt appear to, i havent got an issue.


Interesting to know though..

[Qatar ATC]

Another question ,

When do they instruct aircraft do they have to say Callsign,Turn right or left and heading Degrees or just Turn left or Right heading

[tired-flyboy]

CAP 413 Radiotelephony Manual
Chapter 2 Page 4
1.4 Transmission of Numbers
1.4.2
b) All numbers used in the transmission of altitude, height, cloud height, visibility and runway visual range information which contain whole hundreds and whole thousands shall be transmitted by pronouncing each digit in the number of hundreds or thousands followed by the word HUNDRED or TOUSAND as appropriate. Combinations of thousands and whole hundreds shall be transmitted by pronouncing each digit in the number of thousands followed by the word THOUSAND and the number of hundreds followed by the word HUNDRED;

So my take on QNH 1000mb would be to say 1 (one) 000 (thousand) millibars, :O

Worrying that SRG get it wrong unless Jon5 has misquoted (and i doubt Jon5 has).
Further to this from the current edition of the UK MATS pt1
Appendix E:
3.4.3 All numbers used in the transmission of altitude, height, cloud height, visibility and runway visual range (RVR) information, which contain whole hundreds and whole thousands, shall be transmitted by pronouncing each digit in the number of hundreds or thousands followed by the word 'Hundred' or 'Tousand' as appropriate.
Combinations of thousands and whole hundreds shall be transmitted by pronouncing each digit in the number of thousands followed by the word 'Tousand' followed by the number of hundreds followed by the word 'Hundred';

so again the same way....maybe the college instructors should have a rethink of the RTF of this.
:ok:

[loubylou]

QATAR ATC - to make sure that the heading is not confused with a FL - it is possible to hear heading 160 and think FL160 - especially in airspace where one particular set of levels and headings are commonly used. So this piece of phraseology was introduced.

louby

[2 sheds]

Tired Flyboy

What you are quoting is just what it says - altitude or height values.

The subject of this thread is the transmission of pressure information.

[tired-flyboy]

Your right 2sheds and i was tired when i wrote that.....doh teach me to RTFQ.:oh: :ugh::mad:

Still i'd use wun thousand for the QNH.......

[IShotTheSherif]

For what it's worth - I have always used 1-0-0-0 single digits... :hmm:

[Riverboat]

I don't know who writes CAP 413, whether it is a committee of Health and Safety individuals, or oen eprson, but there are a few odd things about it. Many of these get changed at the next edition, so for about 5 years one would get "shot" for saying something a particular way, and then suddenly what you have been saying all along is the right way after all!

Actually, does anyone know who (specifically) does write CAP 413, as I'd like to discuss something with him/her. (Could phone the CAA, but I am sure someone here knows.)

[2 sheds]

Riverboat

Email to [email protected] but don't blame the addressee. It's done by committee but he is the co-ordinator, has only recently taken on the task and has a list of potential changes a yard (metre?) long.

Spookily, QNH 1000 thingies yesterday morning. Passed by YT as "QNH One Thousand millibars" because I consider the "standard" phrase to be potentially hazardous. All Brit pilots and one or two non-Brits read back as passed, one non-Brit read back as "one zero zero zero" - not a huge sample but interesting.

[Pierre Argh]

Many moons ago, around Christmas time, I was controlling a military helicopter doing a present drop around local hospitals and children's homes using the callsign "Santa 1"

So, on this ocassion, I had delight in informing him the QFE was "One Ho Ho Ho" - at all other times I'd use "One Thousand millibars" for clarity

[fireflybob]

I note that this crazy One Zero Zero Zero has spread to the Volmet too!

This is by my reckoning an increase from 3 to 7 syllables! Almost as annoying as the variability of the wind on Volmet - who the hell cares about the wind direction variability when the speed is 2 kts or evem 10kts? This all eats up valuable time!

[Raptorstick]

Given CAP413 has been updated, i had a read through it and still couldn't find anything to make this topics question legitimate. Also, I take it the word degrees is only used when the bearing ends with a zero (thats what i understood from the amended CAP413).

Anyone got any answer for the QNH/QFE one tousand or one zero zero zero issue??????
What would be the correct answer in the written R/T exam do you think?

Thanks
Raptor

[LEGAL TENDER]

one was taught One Zero Zero Zero by Nats instructors at Hurn
one was taught One Thousand by Nats OJTIs at unit

Practically speaking, I think One Thousand gives less room for error, as a series of Zeros could be easily confused with something else.

[notlgw53]

FFS in what inpenetrable accent is seven mistaken for zero?

[timelapse]

I had it read back to me the other day as "1 bar" - perfect. That should become standard I feel :D

[bookworm]

For all of you doing this DON'T it sounds just like

"Roger descend TO FIFE ZERO ZERO FEET"

And I don't want you at 500ft you're not MAHAN Air!!


Flying Tigers was not so lucky (http://aviation-safety.net/database/record.php?id=19890219-0
)

[2 sheds]

For goodness' sake, this is getting tedious...

Anyone got any answer for the QNH/QFE one tousand or one zero zero zero issue??????
What would be the correct answer in the written R/T exam do you think?

To summarise...

CAP413 (UK RTF Manual) specifies:
When transmitting messages containing aircraft callsigns, altimeter settings, flight
levels (with the exception of FL 100, 200, 300 etc. which are expressed as ‘Flight
Level (number) HUN DRED’), headings, wind speeds/directions, pressure settings,
transponder codes and frequencies, each digit shall be transmitted separately.

The ICAO RTF Manual not only specifies the same but gives specific examples of 1000 hpa and 1010 hpa.

The UK used to specify "one thousand" for that specific value, but then fell in line with ICAO several years ago.

one was taught One Zero Zero Zero by Nats instructors at Hurn
one was taught One Thousand by Nats OJTIs at unit

Therefore, one was taught correctly at the college and one or two unit OJTIs were not up to speed. The CAA have certainly been quite emphatic on this point to the training colleges.

The procedure does seem somewhat illogical and possibly potentially hazardous, I would be the first to say. If you feel strongly - or if there is a mismatch with unit OJTIs - why not direct the effort to CAA, either directly or through CHIRP? Do something about it!

2 s

[LEGAL TENDER]

The procedure does seem somewhat illogical and possibly potentially hazardous, I would be the first to say. If you feel strongly - or if there is a mismatch with unit OJTIs - why not direct the effort to CAA, either directly or through CHIRP? Do something about it!

Because I am perfectly happy with One Thousand. Never experienced a wrong read back with it. On the other hand, the form "One Zero Zero X" or "One Zero One X" does occasionally get wrong readbacks.
In this case, the One Thousand works and appears to be safe, so I am more than happy with the way I was taught by my live OJTIs rather than Hurn.
If the way I was taught is not conforming with the CAP, then I believe it's the LCEs or Training Managers' job to raise the issue, not mine.
At Hurn we used one zero zero zero, but at the college you don't experience wrong readbacks (unless they are deliberate) because the virtual pilots read the QNH off the met screen, rather than reding back the R/T in most cases.

And yes you are right, it's getting tedious. But most pprune threads become like that ;)

[2 sheds]

If the way I was taught is not conforming with the CAP, then I believe it's the LCEs or Training Managers' job to raise the issue, not mine.


The old Nuremburg Defence ploy, eh?

2 s

[LEGAL TENDER]

The old Nuremburg Defence ploy, eh?

arguably inappropriate comment that only contributes to make the thread even more tedious ;)

If what I was doing was unsafe, but kept doing it in the name of "it's not my job to change it", then I would accept the nazi analogy.
But as it appears to be safer than as per "CAP", I think there was no need for such comment :)

I hope we can still be pals !

[2 sheds]

L.T

Most certainly - should have put one of those grinning face thingies next to a lighthearted comment!

But the anomaly is that if one does something different from that which is mandated "in the interests of safety" (as determined by oneself), the fact is that it might well have the opposite effect if it is not what everyone else is doing (e.g. outside the parochial shores of the UK). The point I was making was that if OJTIs are advocating something that is contrary to CAA requirements, ICAO requirements and the expectations of most non-UK pilots, then anybody experiencing this has some responsibility to flag it up as a safety issue.

There - made the point without mentioning the war.

Regards

2 s

[Scott Diamond]

I'm sure that whenever I've tuned into one of them computer voice ATIS's I've heard the QNH given as "QNH Wun Tousand"? Am I right or am I wrong? Not 100% sure what it is! :\

[Kiltie]

CAP413 is renowned as being a frustratingly inaccurate document, despite its constant revisions. Many chapters have techniques in conflict with MATS phraseology.

It even gives an example of an acknowledgement from an aircraft to ATC being read as "G-ABCD." ie callsign only! What an ancient and nonsensical suggestion.

It would seem the person tasked with revising CAP413 is a Monday afternoon part time retiree or certainly someone who doesn't attach much importance to closing the loop between CHIRP and MATS etc. :rolleyes:

PS My take on the subject matter is that pressure settings with a value of 1000 or less should be suffixed with the word millibars. This means one uses "one tousand millibars" to avoid any confusion with an altitude as the suffix has been included to remove the potential ambiguity. Can't remember if I was trained this or read it somewhere but if someone can quote different from an official source I am open to changing my method.

[radarman]

Kiltie,
Took up your first point with a NATS manager, who assured me that the MATS Pt 1 takes precedence over the CAP413.
Another aspect which may confuse the issue is NATS annoying habit of introducing extra bits and pieces of verbiage as company 'best practice'. Can't be arsed myself to look up to see what they say about pressure settings. Any other NATSI's know if the Reichstag has anything to say about passing QNH?

[2 sheds]

From CAP413

Phraseology for air traffic controllers (consistent with CAP 413)
is also published in the Manual of Air Traffic Services (CAP 493).

And on what authority does he claim that one CAP takes "precedence" over another?

Both documents specify exactly the same on the subject of this thread, i.e. are in accord with ICAO.

2 s

[big-blue-sky]

I said it once when I got to my unit after leaving Hurn, never said it again after my OJTI slapped me for it