The airplane was not supposed to carry passengers that morning. It was a ferry flight from Sentani Airport in Jayapura across the mountains to Wamena, repositioning for a legislative election - the aircraft was loaded with voting papers and other cargo for the Highland Papua polls later that month. The crew of six included Captain Sigit Triwahyono, First Officer Lukman Yusuf, two flight attendants, a flight engineer, and a load master. Aviastar had never lost an aircraft before. The BAe 146-300 was a short-haul jet with four engines, popular in Indonesia precisely because its STOL performance and high-wing design suited rough airstrips. Wamena's valley is exactly the kind of place it was built for. In theory.

The weather at Wamena was almost benign. Visibility eight kilometers. Slight haze. Broken clouds. The NTSC investigation found that weather was not a factor in what happened next. On the first approach, low cloud obscured the runway just enough that the crew abandoned it and started a go-around to the right. They were at about 150 feet above the terrain when they began the maneuver - already lower than a standard missed approach procedure would allow. Wamena's runway sits at 1,660 meters elevation, surrounded by ridges that climb steeply in every direction. The proper answer, at that point, was to fly the published missed-approach procedure, climb to safe altitude, and try again. Instead, Captain Sigit turned the aircraft manually onto the downwind leg and began a visual circuit.

The enhanced ground proximity warning system, or EGPWS, is designed for exactly this scenario. It watches altitude, terrain, bank angle, and descent rate, and it shouts at the pilot when any of them goes wrong. On this flight it shouted thirteen distinct alerts. The first was "Don't sink" - a warning that the aircraft was descending after takeoff or go-around. It sounded eight times. Neither pilot responded to any of them. First Officer Lukman, watching Captain Sigit handle the aircraft with increasing wild inputs, said "be careful, Sir." The bank angle increased. Lukman said "Sir Sir Sir open Sir left left." Captain Sigit banked the other way. The bank angle exceeded forty degrees. The nose dropped ten degrees. Lukman repeated the EGPWS words directly: "don't sink." Captain Sigit replied: "ya, ya." The aircraft was now maneuvering aggressively at low altitude below the surrounding ridges, in a circuit pattern for which the published procedures had been discarded.

Three seconds before impact, First Officer Lukman commanded "left turn." The EGPWS shouted "Too low, terrain" and "bank angle" and "terrain, terrain." Lukman called "sir! sir! sir!" The aircraft struck Pikei Hill in Tangma, Yahukimo District, south of Wamena - high terrain the crew should never have been anywhere near at that altitude. The investigation found multiple failures. The pilots had not been adequately trained in EGPWS response. Crew resource management had broken down; the captain was making unilateral decisions while the first officer's warnings went unheeded. The published procedures for a visual approach - the ones that specify who does what and when - had been bypassed. The NTSC concluded, in the careful language of aviation accident reports, that had Captain Sigit executed the appropriate responses to the EGPWS alerts, it is unlikely the crash would have occurred.

Three days earlier, on 6 April 2009, an Indonesian Air Force Fokker 27 had crashed into a hangar at Bandung, killing all twenty-four aboard. Two fatal accidents in Indonesian aviation within a single week caught international attention. The Aviastar crash exposed the particular problem of flying into places like Wamena - valleys that demand both precision and judgment, surrounded by terrain that offers no margin for either. Wamena's approach today remains visual-only, still bounded by the same ridges that Pikei Hill sits on. The EGPWS installed in modern aircraft is a generation ahead of the one that shouted thirteen times into the cockpit of PK-BRD. Pilots still train, and still must choose to listen.