What happened
On the night of January 10, 2014, an Amapola Flyg AB Fokker F27 (registration SE-LIS) was conducting a commercial cargo flight from Sundsvall to Malmö Airport. During the flight, the aircraft experienced a cabin decompression. The crew responded by utilizing oxygen masks and initiated an emergency descent to Flight Level 80.
Upon arrival at Malmö, the aircraft landed on a runway that was wet, though the crew was not fully aware of the runway surface condition. During the landing roll-out, while the crew was still utilizing thrust reversal, the aircraft was struck by a severe wind gust. This caused the aircraft to yaw to the left and veer off the side of the runway. There were no injuries to the two crew members and no damage to the aircraft or the airport infrastructure.
The investigation
SHK examined the flight data, cockpit voice recordings, and the physiological state of the crew. The investigation focused on the sequence of events leading from the decompression to the excursion, as well as the operational limitations of the aircraft. Investigators also reviewed the crew's duty schedules and the regulatory framework regarding medical examinations for personnel working night shifts.
Findings
- The primary cause of the excursion was a severe wind gust acting on the aircraft while thrust reversal was active at a low speed.
- The crew was suffering from both acute and cumulative lack of sleep, which likely impaired their decision-making and attention.
- The flight was planned and executed under weather conditions that exceeded the operator's established crosswind limitations.
- The crew was unaware that the runway surface was wet, partly due to reduced attention and radio interference.
- Thrust reversal was being used at a speed below the recommended 60 knots, and the reversal was asymmetric between the engines.
Safety action
SHK recommended that the Swedish Transport Agency, in coordination with EASA and the Swedish Work Environment Authority, review the application of regulations regarding medical examinations. The investigation highlighted a safety risk where civil flight personnel working night shifts are not consistently offered medical checks to ensure their suitability for night operations.