As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6370 - IAD-HPN - DURING CLIMB, MADE A UNSCHEDULED LANDING, DUE TO NR 1 ALTIMETER FAILED 400 FEET OFF GROUND. AIRCRAFT RETURNED TO GATE WITH NO FURTHER INCIDENTS. MAINTENANCE REMOVED AND REPLACED ALTIMETER. OPS CHECK OK. AIRCRAFT WAS RELEASED AND APPROVED FOR RETURN TO SERVICE. (M)