QNH?

Subject: QNH? 2009-08-13, 11:30

Somebody able to explain to me what this is. Listening to Mildenhall Banter Control, departing aircraft are always told "The QNH is...", with 1014 being the usual value. Completely stumped as to what it is. Dont even know if it is "QNH" or "Q and H"?

Confused,

Ben

Location : Near RAF Aldergrove

Basically an altimeter setting to show altitude above mean sea level.

http://en.wikipedia.org/wiki/QNH

Location : Lincs

Hi Ben,

It is a Q code. It goes back to the days when Morse Code was one of the regular communication modes used in aviation.

http://en.wikipedia.org/wiki/QNH

http://en.wikipedia.org/wiki/Q_code

The Russians still use Morse Code as a method of comms on some of their strategic bombers and transport aircraft. They use International Morse Code with extensive use of internationally recognised Q codes.

Russian Naval Transport Units.

http://www.astrosol.ch/networksofthecisforces/navymorsenetworks/navalairtransportunits/index.html

TJ

Moderator Location : UK Spotter Watch Member : No

and already in the Jargon explanation table at the top of the page Razz

QNH = Altitude above sea leavel based on local station atmospheric pressure (good way to remember: Natural height "NH")

Subject: Re: QNH? 2009-08-13, 15:21

GOOSE wrote:: and already in the Jargon explanation table at the top of the page

QNH = Altitude above sea leavel based on local station atmospheric pressure (good way to remember: Natural height "NH")

Thanks guys!

That'll teach me to post before searching properly Opps

Ben

Location : newark

Hi, I am surprised that you haven't mentioned QFE
This is the other considerably used code Stands for
Field Elevation and is given to ALL landing a/c
although some aircraft do use QNH for landing but this requires
pilot knowledge of airfield elevation.
Airfields give out their "local" altimeter setting region QNH
North East Midlands uses the "Barnsley"
cheers xm594

Location : EGOS Spotter Watch Member : NO NEED

Its actually a'Regional Pressure Setting',ie Barnsley, Humber, Cotswold etc.

Location : various

GOOSE wrote:: and already in the Jargon explanation table at the top of the page

QNH = Altitude above sea leavel based on local station atmospheric pressure (good way to remember: Natural height "NH")

QNH and QFE both need clearer definitions.

QNH is the air pressure at average mean sea level for the current region (or another region if explicitly stated)
QFE is the air pressure at the runway threshold.

So, setting the QFE would result in the altimeter reading 0 feet on touchdown. Using the QNH for landing requires the pilot to know the runway elevation as the altimeter will still be showing a positive height when the wheels hit the runway

QNH is used when travelling across country at low level so that ALL aircraft are using the same base reference for their height
In Upper airspace all aircraft set the same nominal pressure so that flight levels can be accurately used.

Following on from this other entries that could be useful to people might be:
Regional Pressure Setting
Altimeter Setting Region
Transition Level
UK Lower Airspace

Admin Location : Abu Dhabi

QNH is the observed barometric pressure at aerodrome level, corrected for temperature and reduced to mean sea level using the ICAO formula.

Foreign and civil aircraft will use QNH for take off and landing.

Its only the UK Mil that has a love of QFE!!