The Taiwan Transportation Safety Board (TTSB) releases the Final Report on the investigation of China Airlines Flight CI202, the aircraft experienced multiple system failures during landing at Songshan Airport.

On June 14, 2020, China Airlines scheduled passenger flight CI202, an Airbus A330-302 aircraft, registration B-18302, took off from Shanghai Pudong International Airport for Taipei Songshan Airport with 2 flight crew members, 9 cabin crew members, and 87 passengers, for a total 98 persons onboard. The aircraft landed on runway 10 of Songshan Airport at 1746 Taipei local time. At touchdown, the aircraft experienced the quasi-simultaneous failure of the 3 flight control primary computers (FCPC or PRIM), thus ground spoilers, thrust reversers, and autobrake were lost. The flight crew was aware of the autobrake and reversers failure to activate, and applied full manual brake rapidly to safely stop the aircraft about 30 feet before the end of runway 10 without any damage to the aircraft nor injuries to persons onboard.

According to the Transportation Occurrence Investigation Act of the Republic of China (ROC), and the content of Annex 13 to the Convention on International Civil Aviation, the Taiwan Transportation Safety Board (TTSB), an independent transportation occurrence investigation agency, was responsible for conducting the investigation. The investigation team also included members from France Bureau d'Enquêtes et d'Analyses (BEA), Airbus, EASA, China Airlines and Civil Aeronautics Administration (CAA), Taiwan.

Findings related to probable causes:

1. The three flight control primary computers (FCPCs) of the occurrence aircraft became inoperative almost at the same time during touchdown. The root cause was determined to be an undue triggering of the rudder order COM/MON monitoring concomitantly in the 3 FCPC. At the time of the aircraft lateral control flight law switching to lateral ground law at touch down, the combination of a high COM/MON channels asynchronism and the pilot pedal inputs resulted in the rudder order difference between the two channels to exceed the monitoring threshold. The FCPC1 failed first.

2. After the FCPC1 failure, the master control of flight control system was handed over to FCPC2 and FCPC3 in sequence whose asynchronism were also high at that moment; thus eventually all three FCPCs became inoperative. As a consequence of the three FCPCs loss, the thrust reversers, the ground spoilers, and the autobrake system were lost, resulting in an increased landing distance for the aircraft.

Findings related to the risks:

1. During landing, flight controls reconfigured from normal law to direct law after all three flight control primary computers (FCPCs) became inoperative. While all aircraft primary control surfaces were still controllable, the deceleration devices including ground spoilers, thrust reversers, and autobrake were lost, the deceleration of aircraft was relied on manual brake by the pilots.

2. Given all three flight control primary computers (FCPCs) failed seconds after touchdown, should other factors (long flare, runway state, …) have affected the landing distance, the aircraft could have overrun the runway even if the pilots had immediately applied maximum manual brake after realizing the autobrake had failed.

Safety Actions Taken:

During the investigation TTSB noted that the AIRBUS, China Airlines and CAA Taiwan have taken proactive safety actions, as follows:

Civil Aeronautics Administrative, Taiwan
1. Civil Aeronautics Administration released Aviation Safety Bulletin, ASB No： 109-060/O R1 on July 13, 2020.

China Airlines
1. China Airlines released a Flight Operation Information, FOI 2020-034, to its flight crew on July 3, 2020 and updated version (FOI 2021-007) on February 22, 2021.

2. For disseminating potential hazards of the long landing if encountering situation similar to this incident with the condition of short runway, tail wind, and wet runway surface, China Airlines has made the flight safety poster about this case in Q2 2021 and has made it as a lesson learnt in the 1st half EBT briefing to the flight crew to be aware of the long landing risk.

3. Regarding conservative dispatch, CAL has examined every authorized airports. Risk-controlled measure of this event is as follows: For A330 flights using runway length shorter than 9,000 feet, in addition to ensure aircraft relative deceleration systems are normal for dispatch, when calculating landing performance, the dispatchers will not use ground spoilers nor reversers as benefit for conservative dispatch principles.

AIRBUS
1. Short term actions – Communications to Operators

2. FCPC software enhancement addressing the root cause

3. FCPC specification robustness review.

(Detailed information please refer to full Final Report)

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

Vivi Yang, Executive Officer
Tel: +886-2-7727-6217
E-mail:viviy2314@ttsb.gov.tw