What aircraft was involved and where did it happen?

The accident on null involved a aircraft, at MY.

What was the probable cause of the accident?

The aircraft experienced hydroplaning upon landing, which caused it to lose directional control and veer off the runway; this was exacerbated by the pavement condition of the aerodrome.

Hydroplaning causes Twin Otter to veer off runway in Sarawak

A MASwings Twin Otter DHC6-400 veered off the runway at Long Seridan after experiencing hydroplaning during landing, resulting in aircraft damage.

What happened

On 9 May 2020, a MASwings Twin Otter DHC6-400, registration 9M-SSC, was performing a scheduled flight from Marudi to Long Seridan, Sarawak. During the landing phase on Runway 22, the aircraft experienced a loss of directional control. After touchdown, the aircraft veered to the left and rotated toward the starboard side. The movement continued until the aircraft impacted an embankment tail-first, eventually coming to rest on the grass area adjacent to the runway.

Despite the impact, there were no injuries to the two passengers or the two crew members on board. The aircraft sustained significant damage, including a dented elevator, damage to the starboard wing tip, and structural damage to the flaps and ailerons. The impact was severe enough that the control column pinned the pilots to their seats.

The investigation

AAIB Malaysia conducted an investigation that included technical research in collaboration with the University of Defence National Malaysia (UPNM). Investigators analyzed tyre marks, runway pavement conditions, and meteorological data. The research focused on the physical properties of the runway surface and the dynamics of the aircraft's movement during the incident. The investigation also examined the role of the aerodrome's operations assistant and the accuracy of the reported runway surface conditions.

Findings

The primary cause of the excursion was hydroplaning, which led to the aircraft skidding off the runway.
The runway surface was damp, and the aircraft's rotation and veer were a direct result of the loss of friction caused by the water film.
The aerodrome operator's pavement condition required major rehabilitation to ensure safe operations.
There were discrepancies regarding the provision of Aerodrome Flight Information Services (AFIS) and the accuracy of runway surface condition reporting at the STOLport.

Safety action

The investigation highlighted the need for the aerodrome operator to perform major rehabilitation work on the Long Seridan runway pavement.
There is a recognized need to enhance the training of operations assistants to accurately assess and report runway surface conditions to flight crews.