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CL601 flight crew experiences an air data computer failure at FL410. One pilot was in the lavatory; and the PIC at the controls did not detect the failure before altitude and heading deviations occurred.
| Attributes | |
| ACN | 952252 |
| Time | |
| Date | 201106 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | CZYZ.ARTCC |
| State Reference | ON |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | Challenger CL601 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Cruise |
| Route In Use | Direct |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Air Data Computer |
| Person 1 | |
| Function | Pilot Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 80 Flight Crew Total 12700 Flight Crew Type 3500 |
| Person 2 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Flight Instructor Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Engineer Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 80 Flight Crew Total 22000 Flight Crew Type 300 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Track / Heading All Types |
Narrative:
During cruise at FL410 I exited the cockpit and went to the lavatory. We were approximately 70 NM west of buf and cleared direct; communicating with toronto ATC. As I was returning from the lavatory the aircraft entered an unexpected bank. On re-entering the cockpit I noticed that we were several hundred feet off our assigned altitude (low) and slightly off course and that the autopilot; mach trim and yaw damper were disengaged. The PIC was in the right seat and hand flying the aircraft. After taking my place in the left seat I assumed control returning the aircraft to altitude and course and re-engaged the autopilot; mach trim and yaw damper. Our #1 dadc had intermittently failed leading to the various component failures. After several attempts at re-engaging the various systems and reviewing the applicable checklists we concluded our trip without further incident.
Original NASA ASRS Text
Title: CL601 flight crew experiences an Air Data Computer failure at FL410. One pilot was in the lavatory; and the PIC at the controls did not detect the failure before altitude and heading deviations occurred.
Narrative: During cruise at FL410 I exited the cockpit and went to the lavatory. We were approximately 70 NM west of BUF and cleared direct; communicating with Toronto ATC. As I was returning from the lavatory the aircraft entered an unexpected bank. On re-entering the cockpit I noticed that we were several hundred feet off our assigned altitude (low) and slightly off course and that the autopilot; Mach trim and yaw damper were disengaged. The PIC was in the right seat and hand flying the aircraft. After taking my place in the left seat I assumed control returning the aircraft to altitude and course and re-engaged the autopilot; Mach trim and yaw damper. Our #1 DADC had intermittently failed leading to the various component failures. After several attempts at re-engaging the various systems and reviewing the applicable checklists we concluded our trip without further incident.
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.