Incorrect use of 'mb' when QNH 1000 or above by LATCC?
 

I was always told to omit the phrase 'millibars' when the QNH is 1000 or above (eg 'descend altitude 3000 feet, QNH 1000'), and include it when below 1000 (eg 'descend altitude 3000 feet, QNH 999 millibars').

Found the ref. in CAP413, which says mb may be ommitted when QNh 1000 or above provided no confusion or ambiguity will result, and indeed is not used throughout the book.

Heathrow Director seem to say millibars regardless of the QNH - is this a policy? If so, is this because of US pilots who need reminding to set mb and not Inches?

A small point, just curious :)

In Sweden you are not allowed to use "mb" at all, but this is one of the little differences again I guess! :)

There is no policy at Heathrow other than that in the MATS pt 2 which I believe says it is only NECESSARY to use mb when below 1000.

Thinking about it, I guess I probably do tend to use is more often than that, force of habit maybe. For sure, we are particularly careful with the Americans (no disrespect intended).

CJ

As far as the Manchester ATIS / DATIS is concerned, there is a local instruction to use the word millibars at all times.

BmPilot - You are correct regarding the use of the word millibars as quoted in CAP 413. It is, however, "best practice" within Terminal Control to use the word millibars on every occasion because of the potential for confusion with inches of mercury.

I have in the past had a pilot read back 3014 instead of 1014. So it does make sense.

Regards DoB

Personally I take it in hectopascals

Clipped, always willing to help if you have trouble with the conversion.

In my opinion, especially with our American Colleagues the more we use 'Millibars' or FL as appropriate the better -

Anything to try and stop so many level busts.

DoB

You are correct that it is 'Best Practice' especially on Heathrow Approach - may be it should be so in the TMA as well as we are technically only supposed to say ' Millibars' if the pressure is less than 1000

Question answered - Thank you!

I agree with fat controller - I often hear American pilots reading back 'descend 8000 feet' instead of FL80. Not their fault, just what they're used to.

How about a standard transition altitude Europe wide? I find it hard climbing out of Brussels and Amsterdam when the SID stop height is FL60, not 6000 as I'm used to in the London TMA. I personally feel the stop height should always be an altitude - it's one less thing for us to forget at a very busy time of the flight. The exception to this if it is FL100 or above eg) Milan, as we do then have plenty of time to set it.
ps) I know stop HEIGHT is technically the wrong name for it, but its just what we call it!

Hi fatcontroller..I appreciate that nobody likes a smart@rse so I hope this reply doesn`t make me sound like a ..well..smart@rse.

That esteemed body the TC LCC Committee pronounced in August 2000 that........"it is best practice to use "millibars" in all cases." They didn`t differentiate between TMA and Approach.

I`m pretty sure that`s how it stands at the moment unless you know different.

Cheers DoB

;) ;)

Better to be safe than sorry - belts and braces, wives and kids, etc, etc. I say "millibars" with all pressure settings and will continue to do so.

Q. Why do we say "one thousand millibars" and not "one bar"??

DoB

Hi Smart a$$$

No Only Joking - thanks for that, I was still hearing the echo of my LCE who keeps saying


"It's my pet hate that people say Millibars after a QNH of 1000 or more "

So thanks alot I shall now go and slap my LCE

Cheers :D

fc.. well your LCE is rather a Silly Twisted Boy isn't he?

A bit of an 'own goal' this best practice.....

One of my error traps is that if the controller says 'millibars', I know the QNH must be below 1000. (This phraseology standard is published).

There may or may not be safety benefits in the widespread use of the word, but without publicising this change of phraseology, one of my error traps has disappeared. No problem, because it wasn't an important one, but:

WHY DID THE PEOPLE WHO DECIDED ON THIS (AT A LOCAL LEVEL WITHOUT APPROVAL FROM SRG) NOT PUBLICISE IT?

According to the first post on this thread, CAP413 states that 'mb' may be omitted when QNH/QFE is 1000 or more, not must. I read this to be no more than 'legally' optional, and now evidently at variance with 'best practice' at some ATC units.

I have always understood the 'error trap' was to avoid confusion with 'inches', and not to highlight pressures below 1000mb per se.

spekesoftly,

You're right, as far as US operators are concerned. Operating only within Europe, the 'inches' issue is not a complication, and I did say that this was a very minor concern for me. My significant concern, as usual, was with the old left hand/right hand communication issue which seems to plague NATS at the moment.....

The BIG question, 'Why have two different systems at all, when safety may be compromised?' should have been addressed long ago. I believe we should now simply give up fighting our corner, and if the yanks won't change, we should all take to inches of Hg to ensure standardisaton. Any other approach is just political posturing, and has no place in an industry which states that safety is of paramount importance. Likewise, if the French are too pig-headed to speak English (and ICAO too weak to legislate on an issue which has claimed lives), we all need to learn French and other languages to an acceptable operational standard and use them in the appropriate areas. After all, this would go a long way to encouraging standard RT!

In these respects, we are accepting hazards which are known, and significant, and yet refusing to address them.

We should also disband ICAO, on the grounds that they have failed to ensure a safe regulatory regime (but that's another (longer) thread).

All you lucky Europeans should count your blessings for being allowed to transmit a nice user friendly word like "millibar" - down in the Antipodes we're cursed with hectopascals which is such a mouthfull we generally refuse to say it under any circumstances!
Now, if they'd only invent "hectomilliinches" .......:rolleyes:

Spekesoftly - yes, CAP413 does say MAY be ommitted, so there is room for interpretation.
Northernsky - I have 2 main error traps for the QNH - on start up it the ATIS QNH is initially set. The altimeters are then checked against the known elevation of the airfield. QNH is also checked with ATC during start or taxi.

On arrival, QNH is obtained from the ATIS, and set on the standby altimeter. Any gross error should be picked up when we are cleared to an altitude and given the QNH by ATC - the two main altimeters are set independantly by Captain and F/O and then checked against the standby in the approach checks (which was set earlier).

I also thought that it is an ICAO official change from saying "mb" to "hpa" ?? I have certainly applied this for the last couple of years...
Ahhh our good old friends ... " I am flying , not sailing, in International waters ****** Controlled airspace...we do our own thing " American friends .... because although we live and closely share one world we cannot comprimise on measurement standards ...yea I have personally had it, on two occasions, when the QNH has gone to below 1000 hpa that a dear American pilot would take that as inches ...ie 997 hpa is 39.97 inches ...
Ps There was some valid reason why "mb" was replaced with "hpa" ..just can't remember oof hand what it is ...

The word QNH implies Hpa. Noone in the US uses QNH unless their talking HPa wich they are not. When setting InHg the phrase "Altimeter setting" is used.