View Full Version : Convert Millimeters to Hectopascals Jeppesen Manual
bluehawaii
17th Feb 2011, 06:56
Ladies and Gents, can anybody explain how to use the Millimerters to Hectopascals convertion table in the Jeppesen Manual.
chevvron
17th Feb 2011, 11:07
Don't know, (presumably you're referring to millimetres of mercury) but if you would like to convert millibars to hectopascals, the conversion factor is 1/1.
By the way, for UK readers, the UK will convert from mb to hpa in September this year. In order not to increase RTF loading, it has been agreed in principle that the use of the word millibars/hectopascals when passing a pressure setting numerically less than 1000 will be discontinued, on the grounds the UK is the only country in the world to do this.
Rhayader
17th Feb 2011, 11:35
Just multiply the number of mmHg by 1.3332.
eg ; 760mmHg x 1.3332 = 1013.25 mb.
bluehawaii
18th Feb 2011, 22:22
Chevvron, I refering to millimetres and not millibars.
bluehawaii
18th Feb 2011, 22:26
Thanks Rhyayader, I am refering to the convertion chart in the Jeppesen Manual.
Perhaps you could scan and post the Jepp table you are looking at (with the Jepp instructions?). It might help.
HEATHROW DIRECTOR
19th Feb 2011, 09:05
<<that the use of the word millibars/hectopascals when passing a pressure setting numerically less than 1000 will be discontinued>>
Extraordinary and foolhardy decision methinks. If I had a quid for every American pilot who has read back "995 millibars" as "2995" I'd be extremely rich. Obviously there is nothing to prevent controllers from stating the words if they're "belt and braces" types, as I was.
kharmael
19th Feb 2011, 09:30
Extraordinary and foolhardy decision methinks. If I had a quid for every American pilot who has read back "995 millibars" as "2995" I'd be extremely rich. Obviously there is nothing to prevent controllers from stating the words if they're "belt and braces" types, as I was.
Not that I have been taking much notice, but is it common practice for controllers to say "QNH" xxxx when they mean millibars and "Altimmitter" xx.xx when they mean InHg?
Only that's what an ATIS I had the other day said and I think that's a smashing idea to avoid confusion.
HEATHROW DIRECTOR
19th Feb 2011, 12:33
Not in the UK methinks. "Altimeter" is, I believe, a US expression for the QNH setting in inches. That's where a problem may arise: UK controller says "QNH 993", US pilot says "Altimeter 2993"... Particularly for settings below 1000 mb/hP, I believe that the measurement system should be included.
bluehawaii
21st Feb 2011, 02:11
Heathrow Director, that's a good point!