QNH: The pressure 'reduced' to mean sea level, assuming ISA temperature profile from the station/airfield to MSL. An altimeter set to the airfield QNH reads the elevation of the airfield when on the ground.
pressure systems ...
QNH- The barometric pressure as reported by a particular station.
QUADRANT- A quarter part of a circle, centered on a NAVAID, oriented clockwise from magnetic north as follows: NE quadrant 000-089, SE quadrant 090-179, SW quadrant 180-269, NW quadrant 270-359.
(Q-Code) for Air Pressure in hPa calculated to MSL
Quasi-Monopoly Government Organization ...
QNH 995 hectopascal.
No significant change
No significant change in weather expected.
QNH: altimeter setting to indicate height amsl.
RCC: Rescue Co-ordination Centre.
RPM: revolutions per minute.
QNH Setting on the subscale of the altimeter so that the instrument shows elevation or altitude above sea level
QTE True great circle bearing to an aircraft from a station
R/T Radio Telephony ...
2 millibars (standard pressure) when the aircraft is at aerodrome elevation.
QNH: altitude above mean sea level based on local station pressure.
QTE: true line of position from a direction-finding station.
QUJ: true bearing ...
Temperature and QNH
Has a direct effect on air density and thus climb performance. At any altitude where OAT is higher than standard ISA temperature climb performance will be reduced. If QNH is lower than ISA then aircraft climb performance is affected too.
Turbulence and maneuvering ...
Magnetic bearing to a direction finding beacon
Magnetic bearing from the station
Atmospheric pressure at aerodrome level
Magnetic orientation of runway in use
Reading in feet on an altimeter set to 1013MB
Altitude above mean sea level based on local station pressure ...
See also: Aircraft, Altitude, Air, Altimeter, Direct