MD11 flight crew report CADC #1 failure at FL280 triggering several secondary alerts and disabling a...

Attributes
ACN	823539
Time
Date	200902
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	MD-11
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Air Data Computer
Person 1
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 120 Flight Crew Total 7500 Flight Crew Type 120
Person 2
Function	Captain Pilot Flying
Experience	Flight Crew Last 90 Days 260 Flight Crew Total 13000 Flight Crew Type 500
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude

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.

Original NASA ASRS Text

Title: 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.

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.

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.