As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAD-HVN - FLT 6173 - DURING CLIMB, MADE UNSCHEDULED LANDING AT IAD DUE TO RADAR FAILED IN FLIGHT. AIRCRAFT RETURNED TO GATE WITH NO FURTHER INCIDENTS. MAINTENANCE REMOVED AND REPLACED ANTENNA DRIVE. AIRCRAFT WAS RELEASED AND APPROVED FOR RETURN TO SERVICE. (M)