As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 4008 - SHORTLY AFTER TAKEOFF, FLIGHT CREW NOTICED A 100 KNOT DISCREPANCY BETWEEN CAPTAIN'S AND F/O'S AIRSPEED INDICATORS. CREW WAS ADVISED TO RETURN TO FIELD. PIT MAINTENANCE REPLACED CAPTAIN'S SIDE AIRSPEED INDICATOR. ACFT RETURNED TO SERVICE.