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

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?!)

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

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

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

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

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

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.

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!

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

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.

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

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

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.

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

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.

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?

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!!

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.

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)

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!

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:

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 !