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Hectopascals

Old 11th Sep 2017, 22:04
  #21 (permalink)  
 
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Do Yanks still really get confused by QNH settings less than 1000 mb? Really? I only few outside the US for 28 years so maybe a bit shocked.

GF
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Old 11th Sep 2017, 22:41
  #22 (permalink)  
 
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Still keep saying hectopastels for some reason. Don't think they notice though.
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Old 12th Sep 2017, 08:49
  #23 (permalink)  
DB6
 
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The only reason we have to say hectopascals is because they couldn't think of a word with any more f#@king syllables.
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Old 12th Sep 2017, 15:16
  #24 (permalink)  
 
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Originally Posted by LEGAL TENDER View Post
It was introduced in 2011.
Was awkward for a couple of days and then business as usual.

Shows the adaptability to change of some in this profession
Maybe at your unit but you must be in a minority; I still hear people say 'millibars'.
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Old 12th Sep 2017, 19:39
  #25 (permalink)  
 
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Given the spread of units used in aviation, 'millibars' make sense. I Bar = 1 Atmosphere.

Change for the sake of it, driven by The EU........And an extra syllable to-boot.
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Old 12th Sep 2017, 20:32
  #26 (permalink)  
 
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@ Galaxy Flyer
Do Yanks still really get confused by QNH settings less than 1000 mb? Really? I only few outside the US for 28 years so maybe a bit shocked.
Certainly when the US military started operating from Prestwick during the Kosovo conflict, we were very careful about readbacks of altimeter settings. Right up until I retired 4 years ago, there was still the very occasional prompt needed with C130 crews. My suspicion is that possibly, being ANG , they were more used to flying domestically in the USA - or maybe it was just habit ?
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Old 13th Sep 2017, 10:40
  #27 (permalink)  
 
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Originally Posted by Gonzo View Post
Yes, let's ignore the level busts and near-level busts caused by N. American-based crews hearing 992(mb/hpa) and entering 29.92(in) (or similar), let alone the many every U.K. controller has caught at the readback stage.
If you would give links to airporox reports where this has occurred I'd be pleased to reconsider.

The unit added on to the number is immaterial. If a US crew were going to set inches, would it Hectopascal, rather than 'millibar' or 'smarties' really have saved the day?
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Old 13th Sep 2017, 11:06
  #28 (permalink)  
 
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Originally Posted by MaxReheat View Post
If you would give links to airporox reports where this has occurred I'd be pleased to reconsider.

The unit added on to the number is immaterial. If a US crew were going to set inches, would it Hectopascal, rather than 'millibar' or 'smarties' really have saved the day?
If the CAA say you gotta do it, then you gotta do it.
I was on the Phraseology Committee where it was discussed and it was a bone of contention for several other members who didn't want to add the word hectopascals in the same way we had been required to add millibars on the grounds no other country did it.

Last edited by chevvron; 14th Sep 2017 at 05:38.
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Old 13th Sep 2017, 13:39
  #29 (permalink)  
 
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Originally Posted by MaxReheat View Post
If you would give links to airporox reports where this has occurred I'd be pleased to reconsider.

The unit added on to the number is immaterial. If a US crew were going to set inches, would it Hectopascal, rather than 'millibar' or 'smarties' really have saved the day?
? Who said anything about airprox? You don't think level busts, or potential level busts, are serious in and of themselves?

Yes, adding the unit following the value certainly has saved level busts.
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Old 13th Sep 2017, 18:03
  #30 (permalink)  
 
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I was on the Phraseology Committee where it was discussed and it was a bone of contention for several other members who didn't want to add the word hectopascals in the same way we had been required to add millibars on the grounds no other country did it.
Perhaps those members of the PWG should be replaced on grounds of inadequate powers of logic and being Bears of Very Little Brain.

2 s
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Old 13th Sep 2017, 19:54
  #31 (permalink)  
 
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Originally Posted by 2 sheds View Post
Perhaps those members of the PWG should be replaced on grounds of inadequate powers of logic and being Bears of Very Little Brain.

2 s
I'd like to tell you who it was but I can't.
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Old 13th Sep 2017, 20:20
  #32 (permalink)  

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Chevron, your last post opens up a new discussion topic. Why should we not know the names of the unelected few who rule our industry? As far as I'm aware, all other government departments are open.
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Old 14th Sep 2017, 05:41
  #33 (permalink)  
 
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Originally Posted by ShyTorque View Post
Chevron, your last post opens up a new discussion topic. Why should we not know the names of the unelected few who rule our industry? As far as I'm aware, all other government departments are open.
I've already had a slap on the wrist for revealing things about the PWG (in this case the 'change' from Class F to Class E airspace) so I'm not doing it again.
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Old 14th Sep 2017, 06:37
  #34 (permalink)  
 
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Somebody forgot to ask the VOLMET lady to record hectopascals.
On the Scottish version, they are not added when the QNH drops to 999 or below.
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Old 14th Sep 2017, 06:43
  #35 (permalink)  

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Originally Posted by The Fat Controller View Post
Somebody forgot to ask the VOLMET lady to record hectopascals.
On the Scottish version, they are not added when the QNH drops to 999 or below.
Maybe the pilots entering Scottish airspace from overseas are better trained with regard to altimetry....
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Old 14th Sep 2017, 09:44
  #36 (permalink)  
 
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WE were slow to change - hectopascals in use in Pakistan in the 90s.
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Old 14th Sep 2017, 16:30
  #37 (permalink)  
 
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The 'unelected few who rule the industry' come from a variety of aviation related organisations including airlines, civil ANSPs (not just you know who), MOD, GA and the CAA. They receive briefing papers on the subjects to be discussed ahead of the meeting and you'd hope that they might discuss the issues with their peers. That said, they attend the PWG as themselves, not to represent their organisations.

In relation to the topic of conversation, agree that the unit used is immaterial (millibars or hectopascals) but there continues to be a fairly valid reason for its inclusion and it's not just to mitigate against the acts of our colonial cousins. It's something that has been seen in a number of international carriers; albeit infrequently. That said, there have been occurrences where a controller has persevered with obtaining a full readback of the QNH value and the units and the pilot has still set the QNH in inches of mercury

In previous years I'd mention something about Darwin at this point but I've been trying to act more responsibly

The problem that you have is that we don't gather any evidence to demonstrate how often this has proved effective in preventing a level bust. In order for the CAA to remove the requirement to state the units they'd need to produce a solid safety argument that it was no longer required and I don't think that it would be possible to demonstrate an equivalent level of safety given the absence of evidence. Maybe with enhanced Mode S with reliable barometric pressure setting downlinks so that ATS could identify incorrect altimeter settings but the BPS reliability isn't quite there yet.
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Old 15th Sep 2017, 07:14
  #38 (permalink)  
 
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Alternatively, if there were a move for ICAO to standardise the units worldwide and phase out inches of mercury...

2 s
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Old 15th Sep 2017, 22:39
  #39 (permalink)  
 
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What annoys me is aircraft that have their tyre pressures quoted in MPa when my pressure gauge is marked in Bar and psi! (Multiply by 10 to get bar.)
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Old 16th Sep 2017, 10:57
  #40 (permalink)  
 
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I'm very surprised that as The Fat Controller points out, hPa is omitted on Scottish VOLMET. I would imagine that a fair proportion of the Scottish airfield METARS include pressure values of less than 1000.
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