An MD11 flight crew reported apparent loss of a CADC; leading to a decision to return to departure a...

Attributes
ACN	899725
Time
Date	201007
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	MD-11
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	Vectors
Flight Plan	IFR
Component
Aircraft Component	Air Data Computer
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 120 Flight Crew Total 18000 Flight Crew Type 120
Person 2
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 8000 Flight Crew Type 1000
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

Upon climb out we encountered several indications (altitude and airspeed altitude select; wind shear detection fail) consistent [with] CADC problem. Autopilot failed to capture 12;000 on climb. Aircraft had a write-up on a similar problem on previous flight. I was flying the aircraft and first officer was talking to dispatch; maintenance; and operations. ATC requested we climb to a higher altitude. We climbed to FL330 and flew northeast while conferring with company about best course of action. Decided we could not continue on to [our international destination] in rvsm airspace with only one CADC. Told ATC we were non rvsm compliant and requested lower altitude. Cleared to 280 and returned to [departure airport] at request of company.

Original NASA ASRS Text

Title: An MD11 flight crew reported apparent loss of a CADC; leading to a decision to return to departure airport instead of continuing on their international leg.

Narrative: Upon climb out we encountered several indications (altitude and airspeed altitude select; wind shear detection fail) consistent [with] CADC problem. Autopilot failed to capture 12;000 on climb. Aircraft had a write-up on a similar problem on previous flight. I was flying the aircraft and First Officer was talking to Dispatch; Maintenance; and Operations. ATC requested we climb to a higher altitude. We climbed to FL330 and flew northeast while conferring with company about best course of action. Decided we could not continue on to [our international destination] in RVSM airspace with only one CADC. Told ATC we were non RVSM compliant and requested lower altitude. Cleared to 280 and returned to [departure airport] at request of company.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.