What happened
On 20 February 2016, a Boeing 737-900ER, registration PK-LFG, operated by PT. Lion Mentari Airlines, was performing a scheduled passenger flight from Balikpapan to Surabaya. The aircraft was carrying 215 passengers and seven crew members.
During the approach to runway 10 at Juanda International Airport, the aircraft encountered deteriorating weather conditions, including rain and reduced visibility. While descending, the autopilot and auto-throttle disengaged, forcing the crew to fly the aircraft manually. The pilot in command noted that the pilot flying was struggling to maintain control of the aircraft on short final.
The aircraft touched down approximately 552 meters from the runway threshold at a speed 9 knots above the target reference speed. Following touchdown, several mechanical and procedural delays occurred: the thrust reverser levers could not be engaged because the thrust levers were not at idle, the spoilers failed to deploy for 10 seconds, and brake pressure was not applied until 9 seconds after contact. Consequently, the aircraft overran the runway, coming to a stop with the nose wheel positioned just one meter outside the pavement. There were no injuries to passengers or crew, and no damage was reported to the aircraft or surrounding property.
The investigation
The KNKT examined flight data recorder (FDR) and cockpit voice recorder (CVR) information to reconstruct the landing profile. The investigation focused on the aircraft's stability during the final approach and the effectiveness of the deceleration techniques used after touchdown. Investigators analyzed the interaction between the crew's manual flight controls and the aircraft's automated systems, specifically looking at why the thrust reversers and spoilers did not function as intended immediately upon landing.
Findings
- The investigation identified a lack of effective communication and leadership between the crew members, as the difficulty in controlling the aircraft during the approach and the worsening weather did not prompt decisive corrective action.
- The landing distance was significantly impacted by a combination of factors: a prolonged touchdown, a delay in spoiler deployment, the failure to return thrust levers to the idle position, and a late application of the brakes.