As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6266 - IAD-BTV - DURING CLIMB-OUT RETURNED TO IAD DUE TO A COMPASS SPLIT AND THE MODE C INOP. AIRCRAFT RETURNED TO IAD WITH NO FURTHER INCIDENTS. MAINTENANCE RERACKED THE INU AND REINITIALIZED THE AHRS. AIRCRAFT WAS RELEASED AND APPROVED FOR RETURN TO SERVICE. (W)