Indonesian investigators have highlighted operational requirements for landing on wet runways as part of the inquiry into a Garuda Boeing 737-800 excursion at Yogyakarta.

The aircraft (PK-GNK) veered off the left side of runway 09 some 1,600m from the threshold, after arriving from Jakarta. It came to rest 20m off the runway surface.

Runway 09 has a length of 2,200m, says national transportation safety committee KNKT in its preliminary analysis of the 1 February incident.

Meteorological information for time of the landing – in darkness at rain at 19:50 local – indicates the aircraft would have been subject to a tailwind or crosswind component.

The aircraft touched down at about 150kt, slightly to the right of the centreline and flight-data recorder information shows reverse-thrust and braking engaged almost immediately afterwards.

But about 15s after touchdown the data shows a large rudder deflection for around 20s which coincided with a change of heading as the aircraft veered some 50° to the left.

KNKT adds that the flight recorder information also shows "variation" of wind speeds and direction as well as "asymmetry" in brake pressures.

The inquiry has included a large quantity of procedural and operational information regarding landing and braking techniques, including maintaining directional control, on contaminated runways.

KNKT says the captain, who was flying, had accumulated nearly 4,500h on type.

It remarks that the last friction check on the runway had been conducted almost a year before the incident – when advisories stated that such checks should be monthly – and the last cleansing of rubber deposits had taken place four months before.

Garuda issued a notice to pilots 20 days after the Yogyakarta excursion reminding them to review approach and landing techniques in wet weather conditions.

None of the 126 occupants was injured, says the inquiry, and the aircraft was not damaged. But evacuation was not completed until 50min after the aircraft stopped.

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Source: Cirium Dashboard