Oksibil sits in the Bintang Mountains of Papua's far eastern highlands, in a country so remote that BASARNAS, Indonesia's search and rescue agency, would later say the terrain around the crash site had never been previously explored on foot. Ridges rise to above 8,000 feet; valleys are narrow; the weather can shift in minutes from clear to opaque fog that, in pilots' words, "came out of nowhere." The approach into Oksibil's short runway is one of the more demanding in Indonesian regional flying, with few navigational aids. Most airports in Papua relied, in 2015, on visual flight rules and pilot familiarity rather than instrument procedures. The Transportation Ministry itself later acknowledged that some of the country's navigation equipment dated to the 1950s.

At about 14:55, on what should have been the final descent into Oksibil, the ATR 42 lost contact with air traffic control. No distress call was made. The crew gave no indication of trouble. At 15:30, BASARNAS launched a search aircraft, but closing weather grounded the effort within hours. When a search resumed the following day, local residents in the Okbape district of Pegunungan Bintang Regency approached police with an account: they had seen the aircraft strike the side of Tangok Mountain. The wreckage was confirmed shortly afterward. The impact had fragmented the aircraft into small pieces. There was, the recovery teams later said, no chance any passenger or crew member could have survived.

The altitude was too high and the terrain too steep for rescue helicopters to lift wreckage or bodies directly. BASARNAS deployed 250 personnel to Oksibil, and recovery teams had to reach the wreckage either in a three-day walk from the nearest access road or a six-hour drive followed by a steep climb. Three Disaster Victim Identification teams from the Indonesian National Police were deployed to work on identifying the dead - some bodies were intact but burned; others had been so fragmented by the impact that identification required DNA, dental records, and forensic samples sent by families. By the evening of 19 August, 17 bodies had been carried down. The flight data recorder was found on 20 August, four days after the crash.

The flight data recorder had been malfunctioning for more than a year. Trigana had kept the aircraft in service anyway. With the FDR inoperative, investigators from the Indonesian National Transportation Safety Committee had to reconstruct the flight path from cockpit voice recordings and Google Earth. What they found was that Flight 267 had deviated to the right of the approach corridor, into a section of terrain rising to 8,000 feet. The weather in the valley was good, but localized fog - those sudden patches that Papuan pilots know well - had formed in the mountains. The aircraft descended while inside cloud, with the ridges invisible. The NTSC's conclusion was clear: the crash was controlled flight into terrain. The crew flew a serviceable aircraft, under minimal pressure, into a mountainside they could not see.

Trigana's passenger manifest, released to the public, turned out to be from a different flight. The chairman of Sentani Airport was fired. Sixteen airport staff were investigated; two Trigana employees were taken into custody. Transport Minister Ignasius Jonan called the situation "a big mess." Trigana eventually paid 1.25 billion rupiah in compensation for each person killed, with an additional 100 million rupiah per person from the insurer Jasa Raharja. The airline's own safety record entered the public conversation: fourteen accidents between 1992 and 2016, eleven of them hull losses. Indonesian aviation overall sat "below the global average" in ICAO safety audits, with at least one fatal crash every year since 2010. Flight 267 became, with 54 dead, the deadliest ATR 42 accident in history. It also became another number in a statistical pattern that Indonesian regulators have been trying to change ever since.