As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6155 - IAD-ALB - MADE AN UNSCHEDULED LANDING DUE TO CAPTAINS ALTIMETER FAILED. AIRCRAFT RETURNED TO GATE WITH NO FURTHER INCIDENTS. MAINTENANCE REMOVED AND REPLACED CAPTAINS ALTIMETER, OPS CHECK OK. AIRCRAFT WAS RELEASED AND RETURNED TO SERVICE. (M)