The tolerance for Airbus altimeters is +/-75 ft of known airport altitude and +/- 25 ft in between PFD 1 and 2. If I don't get wrong the ISIS altimeters are both servo-assisted altimeters, so the maximum tolerance should be [+/- 30 ft at MSL].
Last edited by fredgrav; 10th Feb 2010 at 09:46.