"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..
Tell ATC that you aren't 200' low, they're 200' too high (Actually,
I've encountered 200' differences when switched to a new ATC sector -
somebody's not calibrated.)

Seriously, if you set your altimeter to the local AWOS/ATIS/ASOS does it
read the published field elevation? If not, the altimeter needs
calibration. If so, it's not the instrument.

The altimeter was reworked a couple of years ago because it got "sticky".
It came back with a yellow tag and a test card indicating it was calibrated
within VFR limits. Since the altitude discrepancy problem existed before
the altimeter rebuild and has persisted since, I'm guessing the Altimeter is
good.


Presumably, it's not the encoder if it passes the bi-annual field check
but do you know if your avionics shop has calibrated their transponder
checking equipment?

No idea, but doesn't the shop have to calibrate its equipment to remain a
certified shop?


When was the last pitot/static check done? Do you have a leak in the
static tubing? If there is a leak in the static system, the altimeter may
be reading cabin pressure which 'could' be higher than a true static.

I've never done a pitot/static check. Is there a DIY procedure for that?


Oh the fun of chasing gremlins...

You got that right!


Bill Daniels

"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