Narrative:

We were level at FL320 when we received an altitude alerter tone and both altimeters altitude alerter lights were on. The captains pfd airspeed indications showed in the hook and his flight director failed. The captains primary altimeter also read approximately 300 ft high. We had no ECAM; warning; cautions or flags. The captain disconnected the autopilot as we cross checked the standby altimeter; my altimeter and our vsis. My pdf; altimeter and vsi were stable and seemed to be giving us good information. The captain transferred control of the aircraft to me and I engaged the number 2 autopilot. The captain switched to air data computer 2 and FD 2 to regain usable info on his pfd. We then asked center what altitude they showed for us. They said we were steady at 320 but for a minute they had us 300 ft high and that they were about to ask us about it. We stated we were having some instrument issues but showed we had been stable at FL320 the entire time. Although we had no ECAM indications; we concluded we had some sort of air data computer failure. We informed center that we were no longer rvsm capable. They cleared us to FL280 and we continued to our filed destination with concurrence and new fuel numbers. Center had nothing further to say about our altitude. Center more than likely got the momentary erroneous altitude read out from the captain's failed altimeter. Once we switched to autopilot 2 they received the correct information. There was no way to prevent the event. I believe we identified the problem in a timely manner and let center know we had an equipment failure that precluded us from operating in rvsm as soon as we were able.

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Original NASA ASRS Text

Title: An A300 Air Data Computer failed in cruise at FL320 which resulted in the Captain's airspeed and Flight Director loss as well as an altimeter error; so control was transferred to the First Officer and the flight descended out of RVSM airspace.

Narrative: We were level at FL320 when we received an altitude alerter tone and both altimeters altitude alerter lights were on. The Captains PFD airspeed indications showed in the hook and his flight director failed. The Captains primary altimeter also read approximately 300 FT high. We had no ECAM; warning; cautions or flags. The Captain disconnected the autopilot as we cross checked the standby altimeter; my altimeter and our VSIs. My PDF; altimeter and VSI were stable and seemed to be giving us good information. The Captain transferred control of the aircraft to me and I engaged the number 2 autopilot. The Captain switched to ADC 2 and FD 2 to regain usable info on his PFD. We then asked Center what altitude they showed for us. They said we were steady at 320 but for a minute they had us 300 FT high and that they were about to ask us about it. We stated we were having some instrument issues but showed we had been stable at FL320 the entire time. Although we had no ECAM indications; we concluded we had some sort of ADC failure. We informed Center that we were no longer RVSM capable. They cleared us to FL280 and we continued to our filed destination with concurrence and new fuel numbers. Center had nothing further to say about our altitude. Center more than likely got the momentary erroneous altitude read out from the Captain's failed altimeter. Once we switched to Autopilot 2 they received the correct information. There was no way to prevent the event. I believe we identified the problem in a timely manner and let Center know we had an equipment failure that precluded us from operating in RVSM as soon as we were able.

Data retrieved from NASA's ASRS site as of July 2013 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.