MD11 flight crew report CADC #1 failure at FL280 triggering several secondary alerts and disabling auto pilot; Captain's airspeed; and altitude. Switching to CADC #2 corrects most problems.

Narrative

During cruise at FL280 in night/IMC; we lost the autoflight system including the autothrottles and FD commands. In addition; we received 3 Level 2 alerts including: 'Select FADEC Alternate;' 'Select Flap Limit Override;' and 'Select Elevator Feel Manual.' Also; we observed miscompared air data between the Captain and First Officer's displays. As the pilot flying; the Captain maintained control of the aircraft in manual flight and we compared the flight display data with the standby system to confirm the valid information. In addition; we elected to run the 'Select FADEC Alternate' checklist which subsequently referred us to the Non Alert Procedure -- Airspeed; Lost; Suspect; or Erratic. Also; we advised ATC of the situation. During the initial observation of the event; the aircraft may have deviated momentarily from assigned altitude. After running the appropriate checklists and isolating the failed Central Air Data Computer; we were able to regain the operation of the autoflight system but were unable to comply with RVSM requirement (only 1 primary altimeter system). We were able to verify the proper data by comparing both sides with the standby instruments.