What happened
On 2 November 2010, a Lion Air Boeing 737-400, registration PK-LIQ, was operating a scheduled passenger flight from Jakarta to Pontianak. The flight, carrying 175 people, encountered difficulties during the approach to runway 15 at Supadio Airport. The aircraft was performing an ILS approach in rainy conditions on a wet runway.
During the descent, the aircraft failed to follow the glide path automatically, forcing the pilot to fly manually. The approach became unstabilized between 1,000 feet and 50 feet above the threshold, with the aircraft speed exceeding recommended limits. Upon touchdown, the crew encountered significant issues with the aircraft's deceleration systems. The thrust reversers were difficult to operate, and the automatic speed brakes failed to deploy immediately, only activating 42 seconds after the aircraft had touched down. Due to the lack of effective braking, the aircraft ran out of runway, coming to a stop approximately 70 meters beyond the runway pavement. All passengers were successfully evacuated, and there were no injuries.
The investigation
The KNKT investigation focused on the mechanical state of the aircraft and the crew's decision-making. Investigators examined the flight data recorder (FDR), which confirmed that the speed brakes deployed long after the touchdown and that the aircraft's deceleration was insufficient for the available runway length. The investigation also reviewed maintenance records, finding that the aircraft had a recurring history of thrust reverser and speed brake deployment issues over the preceding three months.
Findings
- The primary cause of the overrun was the delayed deployment of the automatic speed brakes and thrust reversers, which prevented the aircraft from decelerating within the available landing distance.
- The crew attempted to land despite an unstabilized approach, failing to execute a go-around as required by standard operating procedures.
- Maintenance rectifications performed on the aircraft's braking and reverser systems were inconsistent with the Aircraft Maintenance Manual (AMM), leaving the underlying technical issues unresolved.
- The wet runway conditions and a tailwind component contributed to the increased landing distance required.
Safety action
The KNKT issued several recommendations to address the identified safety gaps:
- PT. Lion Air was advised to ensure maintenance consistency with the AMM, improve crew discipline regarding stabilized approach criteria, and review passenger evacuation guidance policies.
- PT. Angkasa Pura II was recommended to address runway hazards, specifically regarding hydroplaning risks, and to evaluate aerodrome evacuation assistance.
- The Directorate General of Civil Aviation was urged to enhance oversight and surveillance to ensure all safety recommendations are properly implemented.