What happened
On 13 January 2011, an Air Canada Boeing 767–333, registration C–GHLQ, was flying from Toronto to Zurich. During the night crossing of the Atlantic, the aircraft underwent a 46-second pitch excursion, causing the altitude to fluctuate between 34,600 and 35,400 feet. The event was triggered when the first officer, who had been taking a controlled rest, perceived an oncoming US Air Force C-17 as a collision threat and pushed the control column forward with 80 pounds of force. The captain immediately disconnected the autopilot and corrected the pitch. While the aircraft remained stable, the sudden movement caused 14 passengers and 2 flight attendants to sustain injuries from contact with the cabin interior.
The investigation
The TSB examined the flight crew's fatigue levels, the execution of controlled rest procedures, and the physiological effects of sleep inertia. The investigation found that the first officer had been sleeping for 75 minutes, exceeding the 40-minute limit designed to prevent entering slow-wave sleep. Furthermore, the crew did not notify the cabin crew of the rest period, and the captain engaged the first officer in a discussion about approaching traffic before the effects of sleep inertia had dissipated. The investigation also reviewed Air Canada's fatigue management training and the effectiveness of their safety reporting systems.
Findings
- The first officer was suffering from high levels of sleep inertia due to being awakened from a deep sleep during a period of circadian low.
- The first officer's interrupted sleep prior to the flight increased the likelihood of fatigue during the overnight leg.
- The captain's decision to engage the first officer with traffic information before the effects of sleep inertia had worn off prevented the pilot from forming an effective response.
- The controlled rest procedure was not followed, as the rest exceeded 40 minutes and the cabin crew was not notified.
- Air Canada's training on fatigue and controlled rest was insufficient to ensure pilots understood the critical safety boundaries of the procedure.
- Several passengers were injured because they were not wearing seatbelts at the time of the pitch excursion.