Maybe some friction/hysteresis in the altimeter not showing up during the
altimiter check, but not likely.
Maybe some strange internal pressure/vacuum in the cockpit in flight
combined with a leaking static
system, but you passed the static test you say.
You should try and tie it down to which, if either, is right and wrong.
Does the altimeter indicate field altitude when
you set the Kollsman window to the ATIS altimeter setting? One way to get a
pretty good altitude check if you can fly
the glideslope with accuracy and if the plane is so equiped is to pass over
the outer maker with the GS needle dead nuts centered and compare the
crossing altitude with what is
indicated on the approach plate.
"Kyle Boatright" wrote in message
...
I was using Flight Following yesterday and was reminded of a problem that
my RV has displayed for a long time: The transponder and altimeter do not
agree. In general, ATC sees my altitude as about 200' lower than what is
shown on my altimeter.

A couple of facts:

- The transponder/encoder always pass their certification checks.

- The pitot/static system is installed per plans.

Any thoughts?

KB