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QNH is a Q codes defined as the barometric pressure at an airport adjusted to sea level using the ICAO Standard Atmosphere. On the ground, an altimeter set to QNH reads the elevation of the airport.
23 questions
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What is the resolution and the range of QNH?
Where can I find the resolution and the range of QNH in both inHg and hPa? Are there any regulations specifying this?
2
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1
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What is meant by altitude correction above Transition level?
I am a system engineer dealing with Thales ATC product. In my system there is a server called sensor data processor, one of its function is to receive QNH data to do altitude correction. I can't ...
4
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2
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256
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How to determine QNH zones like New Zealand did?
I saw a file stating that New Zealand has 11 zones and was wondering how it was determined and divided, does anyone have any idea?
the paper offers a short description that doesn't cover much ...
- 41
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3
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Which countries use qfe field pressure?
I heard that acrobatic flight, Russians, Americans use qfe but is it always the case?
Also why doesn't everyone use it?
Isn't qfe field pressure better than qnh local pressure...
Does a pilot ever use ...
- 307
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How many times does a pilot usually change local pressure while landing or departing?
The local air pressure (QFE, and therefore QNH as well) may change throughout the day. ATC will advise pilots of the new altimeter setting on a regular basis. How often do pilots truly update this ...
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find the height of the aircraft [closed]
The elevation of Airport A is 150ft AMSL and Airport B is 500FT AMSL. The QNH at A is 1013hPa and at B is 998hPa. An aircraft is overhead A with 5000ft indicated on the altimeter with 1013hPa set on ...
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3
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2k
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Relation between altimeter setting (QNH) formula and the barometric formula
I'm searching for a reliable source for a formulization of the QNH adjustment to the barometric altitude. I found this document from weather.gov that gives a formula for the Altimeter Setting, which ...
- 233
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2
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How can I work out Sea Level Pressure from QNH?
I am a little confused, is the QNH the current pressure at Sea Level? Therefore putting it into the altimeter will give your current altitude on the ground in pressure altitude relative to current sea ...
3
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What geographic reference system do airport towers use?
What geographic reference system (WGS84, EGM96, EGM2008 etc.) do airport towers use when measuring things like aiport elevation and current QNH for airport? Is there even a commonly accepted one ...
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3
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2
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How is Altitude/QNH defined state when passing transition altitude?
Let's say an airplane is climbing towards transition altitude (TA = 5000 ft), and it has it's altimeter set to QNH = 1030 hPa. ...
- 33
2
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1
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Why does the QNH of an aircraft change or need to be changed?
This is mainly a 3 part question.
First, is it the QNH of
of the aircraft?
of the aerodrome?
of the region or area?
Or am I understanding it wrong my looking at it like that?
If the QNH is set to ...
- 81
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Why is True Altitude calculated using the difference from the QNH to 1013hPa?
I have an example for true altitude calculation.
The given Information is
QNH: 983hPa, cruise in FL 85, ISA -10°C in this Alt.
The math and calculations are not hard and i also get to the correct ...
user40920
8
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3
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What’s the setting range altimeters can handle?
What’s the setting range altimeters can handle? Is there a standard requiring a certain range for aircraft to be certified? Are there many occasions where a QNH is so high or low that airplanes have ...
- 3,867
5
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1
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Is it possible to get the QNH value in Austria using a web service?
I got a altimeter sensor which can be connected to a computer and can be adjusted by the QNH!
I need the QNH for Austria, I figured out that the current QNH of the airports are streamed via radio.
...
- 53
2
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1
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Why is there a provision of pressure setting in GPS?
Some of the GPS have a provision of setting barometric pressure (QNH/QFE). How does it work?
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