What defines your flight altitude?
Posted by TheTedandCrew@reddit | aviation | View on Reddit | 9 comments
I live in Americas highest incorporated town at 10,522’ (3,207 m) in Colorado that just so happens to be on the Denver-LA/SEA/SF/everywhere west of Colorado flight path. When I see the altitude of flights above me on FlightRadar, it’s typically around 25,000’. Is that from sea level or the ground level I’m at?
DDX1837@reddit
For aircraft below 18,000', it's the height above mean sea level. The altimeter is set to the local altimeter setting.
If it's over 18,000' then it's pressure altitude. Which means the altimeter is set to a standard setting of 29.92" so all aircraft are operating from the same baseline.
thspimpolds@reddit
(As long as the pressure is 29.92 or higher in the local area)
CasualObserverNine@reddit
Is the air thin there?
TheTedandCrew@reddit (OP)
Very, took me 2-3 months to adapt
joebalooka84@reddit
Yes and as John Denver said, "everybody's high"
nalc@reddit
Unless otherwise specified it is MSL, height above Mean Sea Level
Other terms are AGL, Above Ground Level, and AHO, Above Highest Obstacle (ground level + trees / buildings)
Guadalajara3@reddit
Also based on local atmospheric pressure but anything above 18000 is set to standard sea level pressure of 29.92 for uniformity, so the altitude of 25,000ft or Flight level 250 is based on sea level pressure
agha0013@reddit
Unless specified as above ground, altitudes are based on mean sea level as 0 otherwise you get lots of problems and confusion when people aren't continuously checking maps to verify what the ground elevation is at every single point.
Pr6srn@reddit
Average sea level.