Mon Mar 12, 2018 7:08 pm
#1596947
As a rookie pilot trainee I'm confused about the folllowing statement in the manual (page 25) of my Diamond DA40 training A/C
"QNH: Theoretical atmospheric pressure at MSL, calculated from the elevation of the measuring point above MSL and the actual atmospheric pressure at the measuring point.
Indicated Pressure Altitude: Altitude reading with altimeter set to 1013.25 hPa (29.92 inHg).
Pressure Altitude: Altitude above MSL, indicated by a barometric altimeter which is set to 1013.25 hPa (29.92 inHg). The Pressure Altitude is the Indicated Pressure Altitude corrected for installation and instrument errors. "
This seems to ontradict my earlier understanding as well as other sources thar QSH and Pressure Atltitude are referenced to two different datums. The DA40 manual suggests that MSL and 1013.25hPa refer to the same datum.
Can someone help me out here? Thanks
"QNH: Theoretical atmospheric pressure at MSL, calculated from the elevation of the measuring point above MSL and the actual atmospheric pressure at the measuring point.
Indicated Pressure Altitude: Altitude reading with altimeter set to 1013.25 hPa (29.92 inHg).
Pressure Altitude: Altitude above MSL, indicated by a barometric altimeter which is set to 1013.25 hPa (29.92 inHg). The Pressure Altitude is the Indicated Pressure Altitude corrected for installation and instrument errors. "
This seems to ontradict my earlier understanding as well as other sources thar QSH and Pressure Atltitude are referenced to two different datums. The DA40 manual suggests that MSL and 1013.25hPa refer to the same datum.
Can someone help me out here? Thanks