What happened
On 17 February 2024, an Airbus A321, registration D-AISO, was operating a commercial flight from Frankfurt to Seville. While cruising at FL350 over the Iberian Peninsula, the captain left the flight deck to use the lavatory. Shortly after the captain's departure, the co-pilot experienced a sudden and severe medical incapacitation.
During the period the co-pilot was alone, several involuntary actions occurred due to the medical event. The co-pilot inadvertently deactivated the SEC 3 computer, which triggered a Master Caution and loss of certain spoiler functions. Additionally, a significant force was applied to the right rudder pedal, triggering a Master Warning. Despite these inputs, the aircraft's autopilot and autothrust systems remained engaged, and the flight path was maintained.
When the captain returned to the flight deck approximately eight minutes later, he found the co-pilot unresponsive to entry attempts. After using the emergency access code, the captain gained entry and discovered the co-pilot in a state of physical distress. A doctor traveling as a passenger provided immediate first aid, diagnosing a potential heart condition. The captain subsequently declared a medical emergency and diverted the aircraft to Adolfo Suárez Madrid-Barajas Airport, where the aircraft landed safely and the co-pilot was transported to a hospital.
The investigation
The investigation examined the flight data, cockpit voice recordings, and the medical history of the crew. Investigators analyzed the effectiveness of the flight deck security door procedures and the aircraft's automated systems. The investigation also reviewed the co-pilot's medical certification and the possibility of detecting such neurological events during standard aeronautical medical examinations.
Findings
- The co-pilot suffered a sudden incapacitation caused by a neurological condition that had not been previously detected by the pilot or during recent medical examinations.
- The co-pilot was alone on the flight deck at the time of the event because the captain had briefly vacated the area for physiological reasons.
- The aircraft's automated systems, specifically the autopilot and autothrust, successfully compensated for the involuntary control inputs made by the incapacitated pilot.
- The aircraft continued to fly without active supervision for approximately 10 minutes during the cruise phase.
Safety action
REC 02/25: It is recommended that EASA inform operators about this event so that they may re-evaluate the operational safety and security risks associated with allowing one pilot to remain alone on the flight deck when the other pilot leaves for physiological or operational reasons.