The Taiwan Transportation Safety Board (hereinafter referred to as TTSB) has released the investigation report on the short-term incapacitation of flight crew following landing of Tigerair Taiwan Flight IT237 at Taoyuan International Airport on August 7, 2023.

On August 7, 2023, a Tigerair Taiwan Airbus A320-271N aircraft, registration number B-50023, operated as scheduled passenger flight IT237, the flight departed from Hakodate International Airport, Japan, at 10:24 and was enroute to Taiwan Taoyuan International Airport (hereafter referred to as Taoyuan Airport). The aircraft carried a total of 175 peoples, including 2 flight crew members, 4 cabin crew members, 1 on-duty maintenance personnel, and 168 passengers (including 1 infant). At approximately 14:44, after landing on Runway 23R at Taoyuan Airport and vacating the runway, the aircraft was taxiing on Taxiway E when the captain declared an urgency situation ("Pan-Pan") to the tower, stating that a crew member required medical assistance due to physical discomfort. After the aircraft came to a complete stop, the first officer, who was unwell, received preliminary medical attention and was transported to a hospital for further treatment.

According to the Transportation Occurrences Investigation Act of the Republic of China and with reference to Annex 13 to the Convention on International Civil Aviation, the TTSB is the independent authority responsible for investigating this major transportation occurrence. Agencies invited to participate in the investigation included the Civil Aeronautics Administration (CAA) and Tigerair Taiwan. The "Draft Investigation Report" of this occurrence was preliminarily reviewed and amended during the 68th TTSB Board Meeting on October 11, 2024. It was then forwarded to relevant agencies for their comments. The final investigation report was approved during the 70th TTSB Board Meeting on December 13, 2024 and was officially released.

The investigation identified a total of 9 findings based on the comprehensive review of factual data and analyses and proposed 2 recommendations to enhance transportation safety.

The finding related to probable causes is as follow:

1. After the occurrence aircraft landed at Taoyuan Airport and vacated the runway, the first officer experienced approximately 7 minutes of unconsciousness and incapacitation, and was therefore unable to perform pilot monitoring duties. However, subsequent medical examinations and evaluations by specialists found insufficient evidence to determine the potential cause of the first officer's loss of consciousness.

The 8 other findings are as follows:

1. Taiwan's aviation personnel medical examinations are not deficient in assessing brain and cardiac functions related to maintaining consciousness. The evaluation tools and their application frequency are on par with those used in the United States, the United Kingdom, and Australia.
2. The first officer of the occurrence flight reported experiencing a significant level of fatigue at the time of the incident. However, a review of the first officer 's aircraft handling during the flight revealed no evidence of behavior affecting flight safety due to fatigue, except for the inability to perform pilot monitoring duties after losing consciousness after landing.
3. To manage fatigue risks in flight operations, Tigerair Taiwan has implemented a crew fatigue management procedure using the System for Aircrew Fatigue Evaluation (SAFE) to assess the fatigue risks in crew schedules. However, the predictive model for fatigue indices has functional limitations, as it does not account for individual sleep needs, sleep quality, or circadian rhythm adaptability.
4. Tigerair Taiwan has established a safety incident reporting and analysis system, which is used as a reference for adjusting crew schedules and assignments, in compliance with Civil Aeronautics Administration (CAA) regulations. However, due to its operational characteristics involving a significant number of red-eye, early morning, and overnight flights, combined with the limitations of the fatigue prediction model used for crew fatigue evaluation, there may be fatigue risks when crew members face challenges in adjusting their personal routines. The ICAO Manual for the Oversight of Fatigue Management Approaches (ICAO Doc 9966) recommends establishing mechanisms for collecting and investigating fatigue-related data from reports and safety incidents, as well as enhancing fatigue management training. These measures can improve awareness, responses, and fatigue management across all organizational levels.
5. Tigerair Taiwan's employee leave and absence policies require flight crew members performing overnight flight duties to provide certification from a legitimate medical institution or physician if they are unable to perform tasks due to fatigue. This requirement may discourage crew members from taking leave when experiencing fatigue that could potentially impact flight safety, thereby increasing the difficulty of addressing fatigue-related risks.
6. The flight crew of the occurrence flight held valid aviation licenses and medical certificates issued by the Civil Aeronautics Administration (CAA), meeting both CAA and company requirements. A review of their training and examination records revealed no abnormalities related to this occurrence. Neither the captain nor the first officer regularly used medication, and post-landing alcohol tests at Taoyuan Airport returned a result of zero. There is no evidence indicating that alcohol or medication issues contributed to this occurrence.
7. During the first officer's incapacitation, the captain effectively managed the aircraft, coordinated with the cabin crew for assistance, declared an urgency situation to air traffic control, and requested ambulance support. There were no delays or findings suggesting that the execution of procedures related to crew incapacitation compromised flight safety.
8. The aircraft's weight and balance were within the limits, and there were no anomalies in the airworthiness data prior to the flight.

The 2 Transportation Safety Recommendations are as follows:

To Tigerair Taiwan

1. In reference to the relevant recommendations in the ICAO Manual for the Oversight of Fatigue Management Approaches (ICAO Doc 9966), continue to improve fatigue management to address the fatigue risks arising from operational characteristics, such as a higher number of early shifts, overnight missions, and red-eye flights.

To Civil Aeronautics Administration

1. Collect cases of crew incapacitation during flight operations, analyze and summarize potential causes and contributing factors, and use this information as a reference for safety promotion and risk management within the civil aviation industry.

Full Final Report in Chinese is available for download at https://www.ttsb.gov.tw

Ya-Ting Chang, Secretariat Office

Tel: +886-2-7727-6210

E-mail: yating@ttsb.gov.tw

Thomas Wang, Aviation Occurrence Investigation Division

Tel: +886-2-7727-6309

E-mail: wang@ttsb.gov.tw