OK... even still, though, the GPS isn't too accurate, and is based on absolute
altitude, not barometric altitude (mentioned previously). Also, the temperature
affects the altimeter... how high AGL were you? I read an interesting article (avweb,
I think) regarding temperature correction and obstacle clearance. When the altimeter
reading is down low and temps are cold, the higher you go the more error the altimeter
tells you. So, if the altimeter setting is down in the valley at 1000' MSL, but
you're shooting the approach with MEA at 10K', there can be issues with terrain
avoidance. Supposedly Canadian and AK folks get more indoctrination to this than
those in the lower '48.

-Cory

Hankal wrote:
:You didn't specify if your GPS was connected to the altitude encoder or not.
:
:If it's an IFR GPS, it'll be connected to the encoder, which only outputs the
:altitude

: My GPS is not connected.
: Under most conditions it agrees with my
: altimeter.
: It was just strange that the GPS and ATC
: did not not reflect the same as my altimeter.
: Hank

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