What happened
On August 7, 2023, a Tigerair Taiwan Airbus A320-271N, registration B-50023, arrived at Taoyuan International Airport from Hakodate, Japan, as flight IT237. The aircraft was carrying 175 people, including 168 passengers.
After landing on runway 23R, the aircraft exited the runway and was taxiing via taxiway E. During this period, the pilot monitoring (the captain) declared a Pan-Pan emergency to the tower, stating that a crew member was unwell and required medical assistance. The first officer, who had been acting as the pilot flying, had experienced a period of unconsciousness lasting approximately seven minutes. After the aircraft came to a complete stop, the first officer was evaluated by medical personnel and subsequently transported to a hospital.
The investigation
The Taiwan Transportation Safety Board (TTSB) investigated the incident, examining the flight crew's medical records, fatigue management systems, and the sequence of events. The investigation confirmed that the aircraft's weight and balance were within limits and all pre-flight airworthiness information was normal. The captain's response to the emergency, including communicating with the cabin crew and requesting medical aid, was found to be prompt and effective.
Medical examinations and specialist evaluations conducted after the event failed to provide sufficient evidence to identify a specific medical cause for the first officer's loss of consciousness. Additionally, testing confirmed that neither pilot had consumed alcohol or drugs, with blood alcohol levels recorded at zero.
Findings
- The first officer experienced an unexplained loss of consciousness for approximately seven minutes while taxiing, which prevented the execution of pilot monitoring duties.
- The first officer reported feeling a significant level of fatigue at the time of the incident, following a period of recent flight schedules involving several red-eye and overnight shifts.
- While the airline utilizes the System for Aircrew Fatigue Evaluation (SAFE) to monitor fatigue risks, the investigation found that this module has limitations, as it does not account for individual factors such as personal sleep quality or the ability to adjust to circadian rhythm changes.
- The airline's operational profile, which includes frequent early morning and overnight flights, may contribute to fatigue risks when crew members are unable to adequately adjust their sleep patterns.