As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT NR 6211 - IAD-PVD - DURING CRUISE, RETURNED TO IAD DUE TO THE AIRSPEED INDICATION SPLIT OF 100 KNOTS, WITH THE CAPTAINS AIRSPEED INDICATING 30 KNOTS OVER THE OVERSPEED WARNING. AIRCRFT LANDED AT IAD WITH NO FURTHER INCIDENTS. MAINTENANCE REPLACED THE NR 1 AIR DATA COMPUTER. AIRCRAFT WAS RELEASED AND APPROVED FOR RETURN TO SERVICE. (M)