Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Diverted; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
Approaching ZZZ (50 minutes into flight); Captain's airspeed tape went to zero and altimeter jumped to 250 ft. high at FL340. FD (Flight Director); AT (Autothrottles); and AP (Autopilot) went away accordingly. Captain's airspeed slowly recovered and failed multiple times. Priority handling was asked with no firetruck response needed. Diversion was coordinated with Dispatch to ZZZ. First Officer's data was always correct. Approach and landing were uneventful. ZZZ Approach and Tower were very helpful with groundspeed calls to verify airspeed. The courier compartment was wet when we arrived at the plane and an E&E Inspection was accomplished for water intrusion before departure. [This was probably caused by] ADC failure.
A300 Captain reported diverting due to unreliable airspeed and altitude indications.