Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 55; Flight Crew Type 8500
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
At approximately 1;500 AGL on departure the right Air Data Computer (ADC) failed and the First Officer had Yellow Altitude and Airspeed flags on his Primary Flight Display (PFD). He selected the left ADC and climb was continued to FL320 as the relief pilots researched the Aircraft Operating Manual and I contacted Dispatch and Maintenance Control for guidance. Maintenance Control advised no corrective procedure was available and I elected to pull and reset the Right ADC Power Circuit Breaker in hopes this might correct the malfunction. The ADC remained inoperative and further investigation revealed two ADC's were required to traverse RVSM airspace. Dispatch coordinated our return with Center and; when clearance was received we dumped fuel on the return. An uneventful diversion was completed.
A long range air carrier flight had to return to their departure airport when a failed ADC and the need to utilize RVSM airspace proved incompatible.