What happened
On 10 February 2018, a Ryanair Boeing 737-8AS, registration EI-EKI, was descending through the Canary Islands airspace. The aircraft was initially cleared to descend from FL370 to FL130. However, while the aircraft was crossing FL368, air traffic control amended the clearance, instructing the crew to level off at FL360 to avoid a potential conflict with another aircraft.
As the aircraft continued its descent, the pilot selected the altitude hold mode to comply with the new instruction. At that moment, the aircraft was passing through FL364 at a high rate of descent. Believing the automated recovery was too slow and fearing they had already descended below the authorized altitude, the pilot decided to disengage the autopilot to manually return to FL360.
This manual intervention led to significant fluctuations in the aircraft's pitch angle and vertical acceleration, which peaked at 1.69 g. During this abrupt maneuver, a passenger who was standing in the rear of the cabin fell, resulting in one serious injury (a broken leg) and one minor injury to a child. The aircraft sustained no damage.
The investigation
The CIAIAC investigation examined flight recorder data, radar tracks, and communications between the crew and air traffic control. The investigation also reviewed the actions of the air traffic controllers and the effectiveness of the medical response at Fuerteventura Airport.
Investigators found that the pilot's decision to fly the aircraft manually at high altitude caused the large swings in pitch and vertical acceleration. The investigation also noted that the seatbelt sign was not illuminated at the time of the event, as the crew had not yet initiated the descent procedure for landing. Furthermore, the investigation highlighted delays in the medical response at the destination airport, where the arrival of an ambulance was delayed due to the availability of only one emergency vehicle on the island.
Findings
- The primary cause of the accident was the sudden manual maneuver executed by the crew to maintain the specified flight level.
- A contributing factor was the decision to disengage the autopilot, which made the recovery maneuver abrupt.
- The aircraft was descending at a high rate of descent when the instruction to level off was received, making manual recovery difficult.
- The passenger's injury was a direct result of the vertical accelerations experienced during the pitch changes.