The crew of a Batik Air Boeing 737-900ER did not recalculate the aircraft’s landing distance shortly before a runway overrun accident at Yogyakarta’s Adisuciptio International airport on 6 November 2015.

Indonesia’s National Transport Safety Committee (NTSC) says in its final report on the accident that the aircraft involved was registered PK-LBO and was operating a flight from Jakarta Soekarno-Hatta International airport with 168 passengers and crew on board.

During the approach to Yogyakarta, the flightcrew received updated weather information, which caused them to configure flaps at 40 degrees and use auto-brake setting three. After noticing cumulonimbus clouds on the radar, the crew changed the setting to 30 degree flaps as a windshear precaution.

2min later, the crew contacted Adisucipto Tower and established the aircraft to intercept the runway 09 localiser. They also changed the auto-brake selection to maximum, after being advised that the runway was wet.

The 737 subsequently touched down 427m beyond the threshold, and maximum reverse-thrust was applied. As it approached the end of the runway, the aircraft’s auto-brake was overridden by maximum manual braking, and the pilot-in-command turned the aircraft to the left.

This led the aircraft to stop 84m from the end of the runway, and 80m left of the runway’s centreline extension. The aircraft suffered damage to its belly, and the lock pin of the front nose gear broke into three pieces, causing the nosewheel to fold backwards.

In its analysis, the NTSC noted that the crew failed to recalculate the landing distance after changing the flap configuration. A callout of speed above the reference landing speed by the co-pilot may have caused both pilots to be unaware of the required landing distance, and led them to continue with the landing pattern.

The prolonged touchdown and landing, coupled with the use of lower brake pressure for 305m, was insufficient for the aircraft to stop before the end of the runway.

It adds that good braking action would have been sufficient for the 737 to stop with a “relatively narrow margin”, while the runway condition may have contributed to the reduction of the aircraft’s deceleration rate.

Following the accident, Batik Air issued several notices to pilots. These include instructions on wet weather conditions, taking extra precautions on landing at Yogyakarta during wet weather, and implementing improved emergency training.

The NTSC also urged Adisucipto airport to perform daily inspections of the movement area and develop a procedure for measuring water depth on runway and taxiways.

Air traffic control provider AirNav Indonesia was also recommended to look into developing an instrument approach for the airport’s runway 27.

Source: Cirium Dashboard