What happened
On April 23, 2018, TransAsia Airways flight DA 7012, a Viking Air DHC-6-400 with registration B-55573, was operating a scheduled passenger service from Qijin (Kinmen) Airport to Kaohsiung International Airport. The flight was carrying 15 passengers and two crew members.
At approximately 17:22 local time, the aircraft landed on runway 09 at Kaohsing International Airport under right crosswind conditions, with wind speeds between 10 and 19 knots. During the landing roll, the pilot attempted to correct the aircraft's lateral deviation but incorrectly applied the nose wheel steering handle to the left. This caused the aircraft to veer off the runway at an angle of approximately 35 degrees. The aircraft continued to turn left, eventually coming to a stop on the grass on the left side of the runway, having rotated approximately 180 degrees. There were no injuries to the 17 occupants, and the aircraft sustained no substantial damage.
The investigation
The Taiwan Transportation Safety Board (TTSB) examined the mechanical, operational, and organizational factors surrounding the excursion. The investigation confirmed that the nose wheel steering and hydraulic systems were functioning normally prior to the event and that the nose wheel was in the centered position before landing. The investigation also analyzed the pilot's workload, the airline's scheduling practices, and the cockpit environment.
Findings
Causal and contributing factors
- Pilot Error: The pilot flying incorrectly manipulated the nose wheel steering handle to the left while attempting to correct for the crosswind.
- Pilot Fatigue: The pilot had completed eight flight segments on the day of the accident, with a duty period exceeding 10 hours. The cumulative workload and high flight frequency contributed to a state of diminished alertness.
- Lack of Standardized Procedures: The airline's manuals lacked specific instructions regarding standard callouts for lateral deviations during the landing roll and did not define specific timing or speed limits for nose wheel steering usage.
- Training Limitations: At the time of the accident, the airline lacked Level D full-flight simulators for the DHC-6-400, meaning crews relied on aircraft-based training which could not effectively simulate all weather scenarios.
- Operational Risks: The airline faced pilot shortages, particularly for captains, which led to high-risk scheduling patterns. Additionally, the lack of effective air conditioning in the cockpit during summer months contributed to crew discomfort and heat-related fatigue.
Safety action
Following the investigation, the TTSB issued several recommendations to TransAsia Airways and the Civil Aviation Administration to improve safety, including:
- Standardizing procedures for nose wheel steering and lateral deviation callouts.
- Implementing a plan to acquire Level D flight simulators for the DHC-6-400 fleet.
- Reviewing crew scheduling to mitigate fatigue risks and addressing cockpit environmental conditions.