A freighter B737-300 was operating a scheduled freight flight from Sentani Airport, Jayapura to Wamena Airport, Wamena, Papua (both in Indonesia). Onboard the aircraft were 14.913 kilograms of cargo, two pilots and a loadmaster. During flight preparation, the crew was informed that on the right base runway 15 of Wamena Airport, in the area of Mount Pikei, low cloud was observed with the cloud base was increasing from 200 to 1000 feet and the visibility was 3 km.
The left main landing gear left behind on the runway (© KNKT)
At 21.45 UTC the aircraft lifted off from Sentani airport with the captain as pilot flying (PF) and the co-pilot as pilot monitoring. Th aircraft climbed to an altitude of 18.000 feet for the short 151 miles (241 kilometres) flight. After starting the descent towards the destination the crew determined that a visual approach was possible wit the prevailing weather. During the initial approach, the crew were informed that they were #3 for landing, giving orbiting instruction over waypoint 8 nm from runway 15 at Sentani. After two orbits ATC cleared the aircraft for a descent to 7000 feet (~2000 feet AGL - Above Ground Level). As the aircraft turned final the PF was under the impression that they were on the right-hand side of the extended centerline.
The damaged fuselage and flaps (© KNKT)
The approach was continued and at ~500 feet RA (Radio Altitude), while 2 nm from the runway the crew became visual with the runway. A short while later the Enhanced Ground Proximity Warning System (EGPWS) aural warning “SINK RATE” activated, to which the PF reacted by reducing the rate of descent. While over the threshold the pilot felt the aircraft sink and the aircraft touched down hard, the FDR (Flight Data Recorder) recorded a vertical acceleration of 3.25 g on touchdown. (The FDR recorded pitch down up to 11°, the calculated rate of descent reached up to 3,200 feet/minute, the aircraft rolled to the right up to 28° and the speed increased by 7 knots).
The damaged left-hand engine (© KNKT)
As a result, both main gears collapsed and the aircraft settled on its belly and engine cowlings. It continued to slide for over 1700 meters, coming to a stop 1.890 meters from the runway threshold. Damage to the aircraft was extensive, all occupants escaped without injury.
FDR Data from the approach and landing (© KNKT)
An investigation was launched by the KNKT (Komite Nasional Keselamatan Transportasi), the transportation safety committee of Indonesia,) In their report the following damages to the aircraft were listed;
Both mainlanding gears failed
Nose landing gear damaged
#2 (LH inboard) tire blown out
Inner flaps (LH & RH) damaged
Left engine cowling detached
Horizontal stabiliser damaged
Lower fuselage damaged
Left-wing to body fairing torn
A long list of findings are presented in the report, summarised the most noticeable are;
At the time of the approach, the visibility was 3 kilometres, minimum visibility for the VFR approach was 4.8 kilometres
Discussion between the crew about visual references not being visible indicates that a VFR approach could not be made.
PM called for a go-around at 400 feet AGL, this was not followed up by the PF.
The aircraft landed before landing clearance was issued by ATC
The approach was not stabilised
Video of the aircraft sliding down the runway after the main gears had failed (Source Youtube © CNN Indonesia)
Several safety actions were taken by the operator, DGAC (Directorate General of Civil Aviation - Indonesian Civil Aviation Authority) as a result of this accident. They can be found for the readers' reference in the preliminary report (on which this report is based) by clicking on the .pdf file below;