Hectopascals

[Garry Russell]

Suddenly the RT is referring to pressure as Hectopascals instead of Millibars although they have the same value

Just noticed this today

Anyone know why the change??

[Hot_Charlie]

Suddenly the RT is referring to pressure as Hectopascals instead of Millibars although they have the same value

Just noticed this today

Anyone know why the change??

Why? No idea (probably the French)! It certainly doesn't make the RT any shorter since it changed!

[Garry Russell]

Only this afternoon I've noticed this...tbh it sounds clumsy

I'm sure they weren't earlier unless it this particular controller.

The pilots repeat the message without a flinch

[DavidK]

Probably for SI conformity -- not to mention some advertisement for our French cousins' scientist...

[SkippyBing]

I believe it's because EASA has now stood up as the aviation authority for all JAA states. Personally I just say the number otherwise you end up with unnecessarily long r/t calls.

[NigelC]

Yup, the Eurocrats in their Ivory Tower in Cologne have ruled that the millibar is no more!

[Garry Russell]

I still say Centigrade

[NigelC]

[cstorey]

Actually, hPa have been around for many years, and are precisely the same as mB . Typical of the deadarses that the terminology has, pointlessly, to change

[PeteP]

Only this afternoon I've noticed this [...] I'm sure they weren't earlier unless it this particular controller.

Hi Garry,
The change actually happened in October last year but it's not surprising you haven't heard it used before now. UK controllers are only required to explicitly state the unit (hectopascals now) if the pressure setting is below 1000mB/hPa and, as it's not an ICAO requirement, many other countries don't even do that. So, if the pressure has not been particulary low when you've been listening (or you're listening to ATC outside the UK) you won't have heard it used.

Incidentally, the reason it's done like that in the UK is that there have been a number of incidents in the past where 'septics' have taken settings such as 992 (mB/hPa) to be 29.92 (in/hg) resulting in dangerously mis-set altimeters - an error of approximately 600ft in that particular example!

The next thing to listen out for is the loss of all those low flight levels as the UK 'harmonises' its Transition Altitude at 18000ft but that's a while away yet.
Pete