The Taiwan Transportation Safety Board (TTSB) releases final report on the investigation of a Mandarin Airlines flight AE788 veered off runway during landing on runway of Taichung/ Cingcyuangang Airport (Taichung Airport).

On August 22, 2018, a Mandarin Airlines ATR72-212A passenger aircraft, flight number AE788, registration number B-16852, departed from Penghu Airport to Taichung Airport, with 2 flight crew, 2 cabin crew and 70 passengers, totally 74 people on board. The aircraft veered of the runway during landing on the 36 Runway of Taichung Airport and resulted in collision damage of aircraft and 3 runway edge lights. The on board persons were all safe.

According to the Transportation Occurrence Investigation Act of the Republic of China, and referring to Annex 13 to the Convention on International Civil Aviation, the TTSB, an independent transportation occurrence investigation agency, started the investigation. The organization or agency been invited to join the investigation team included: Bureau d'Enquêtes et d'Analyses of France, ATR-GIE Avions de Transport Régional, Civil Aeronautics Administration, Ministry of Transportation and Communications, Air Force Command Headquarters, Ministry of National Defense and Mandarin Airlines. The Final Report was reviewed and approved by ASC’s 81th Council Meeting on July 16, 2019.

Findings related to probable causes:

1. The occurrence flight crew did not comply with Mandarin Airlines Flight Operations Manual, the first officer acted as the pilot flying for the approach and landing while the visibility during approach did not meet the first officer takeoff and landing minimums.
2. During the time the pilot flying disengaged the autopilot and controlled the aircraft manually, the aircraft continued to deviate from the runway center line to the left. The pilot flying was unable to manage the lateral control of the aircraft and correct the aircraft back to the runway center line.
3. The captain allowed the aircraft to deviate from the runway center line to a large extent, reducing the fault tolerance range of safety margin, and did not recognize the possible risk of aircraft slow and continuous left deviation. The rain affected the visibility right before the aircraft touched down. After the aircraft landed near the runway edge line and continuously deviated to the left, the captain then took over the control. It was too late for the correction and caused the aircraft to veer off the runway.

Findings related to risk:

1. Before the occurrence aircraft descent, the contents of the approach briefing by the pilot flying included only approach procedure related information. The briefing did not follow the company's CFIT/ALAR/RWY EXCURSION AVOIDANCE checklist and threat and error management content, examining possible risk increasing to approach landing due to threats of heavy rain, thunderstorms and low visibility.
2. 2.The ground base of the runway edge lights within the runway strip of Taichung Airport existed potholes and hard vertical cement concrete structures. It may increase the possibility of aircraft damage during runway veer-off occurrence.

Safety Recommendations

To Mandarin Airlines:

1. Request flight crew to perform flight operations in accordance with the relevant manuals, including first officer takeoff and landing minimum standards, the implementation of risk assessments and briefings, the mastery of safe landing guidelines, and the timing the captain to take over the control in an unsafe condition.

To Civil Aeronautics Administration, Ministry of Transportation and Communications:

1. Supervise Mandarin Airlines to request flight crew performing flight operations in accordance with the relevant manuals.
2. Coordinate and cooperate with the Air Force Command Headquarters, Ministry of National Defense, establishing a continuous object inspection mechanism within the runway strip to timely identify and eliminate objects that may cause impact damage during aircraft runway veer-off.
3. Coordinate and cooperate with the Air Force Command Headquarters, Ministry of National Defense to evaluate and improve the runway average transverse slope of Taichung Airport.

To Air Force Command Headquarters, Ministry of National Defense:

1. Coordinate and cooperate with the Civil Aeronautics Administration, Ministry of Transportation and Communications, establishing a continuous object inspection mechanism within the runway strip to timely identify and eliminate objects that may cause impact damage during aircraft runway veer-off.
2. Coordinate and cooperate with the Civil Aeronautics Administration, Ministry of Transportation and Communications, referring to the Civil Aerodrome Design and Operation Standards to evaluate and install runway center line lights of Taichung Airport
3. Coordinate and cooperate with the Civil Aeronautics Administration, Ministry of Transportation and Communications to evaluate and improve the runway average transverse slope of Taichung Airport.

Full Final Report is in Chinese only and available for download at http://www.TTSB.gov.tw

Sherry Liu, Safety Investigator