What happened
On 6 November 2015, a Batik Air Indonesia Boeing 737-900ER, registration PK-LBO, was performing a scheduled passenger flight from Jakarta to Yogyakarta. The aircraft, carrying 168 people, was operating on runway 09 at Adisutujipto International Airport. During the landing phase, the aircraft experienced a long touchdown at the end of the touchdown zone. Due to a combination of a 5-knot tailwind, high touchdown speed, and a wet runway surface, the aircraft could not stop within the available runway length. The aircraft subsequently exited the runway, resulting in the nose wheel folding backward and the aircraft coming to rest on the grass area.
The investigation
The KNKT investigation examined the flight data, cockpit voice recordings, and aerodrome information. Investigators analyzed the aircraft's performance, specifically looking at the landing distance required versus the distance available. The inquiry reviewed the meteorological conditions, noting the wet runway and the presence of a tailwind. The investigation also scrutinized the braking action, the use of autobrakes, and the timing of thrust reverser application. Furthermore, the investigators reviewed the airport's infrastructure, including the availability of approaches for runway 27 and the accuracy of the aerodrome charts provided to operators.
Findings
Several critical factors contributed to the runway excursion:
- The aircraft touched down significantly late in the touchdown zone.
- The touchdown occurred at a speed 13 knots above Vref, compounded by a 5-knot tailwind.
- The primary cause was the extended landing distance resulting from the combination of a late touchdown, high speed, and a tailwind.
- Braking effectiveness was reduced due to the wet runway surface (medium braking action).
- The crew did not fully utilize deceleration devices, as evidenced by lower brake pressure for 1,000 feet after the autobrakes were disconnected and the premature removal of thrust reverser application at a speed higher than recommended.