Investigation Summary
The flight was a maritime surveillance mission conducted for the Indonesian Directorate General of Marine and Fisheries Resources Surveillance. During the flight, the Honeywell HT1000 GNSS system repeatedly entered a 'Degrade' state, which should have triggered a 'DGR' amber alert on the Electronic Horizontal Situation Indicator (EHSI). This degradation resulted in a significant lateral offset between the aircraft's actual position and the position displayed to the crew. As the flight approached Makassar, the crew requested radar vectors based on their erroneous internal navigation data. Air traffic control (ATC) observed the aircraft deviating from the expected path but did not recognize the severity of the navigation failure. The crew's situational awareness was further compromised by weather deviations to avoid cumulonimbus clouds, which pushed the aircraft east toward higher terrain. The ground-based MSAW system, intended as a final safety net, failed to trigger because the terrain database for the Makassar surveillance system had never been properly configured. The aircraft was flying below the Minimum Sector Altitude (MSA) of 8,500 feet and the ATC surveillance minimum of 6,000 feet. The aircraft's Enhanced Ground Proximity Warning System (EGPWS) eventually issued 'TERRAIN' and 'PULL UP' alerts, but the warnings occurred only seconds before the aircraft impacted a cliff at 4,327 feet.
Final Conclusions
The investigation is ongoing. The National Transportation Safety Committee (NTSC) released Preliminary Report KNKT.26.01.01.04 on 20 February 2026. The report identifies GNSS degradation, lack of crew cross-checking with conventional navigation aids, and the unconfigured state of the ATC MSAW system as primary factors in the CFIT event.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
58 years old, held ATPL.
First Officer
25 years old, held CPL.
Systems & Failure Modes
Honeywell HT1000 GNSS
The primary navigation system which entered a degraded state, providing inaccurate position data to the cockpit displays.
Minimum Safe Altitude Warning (MSAW)
A ground-based safety tool for air traffic controllers that failed to alert because terrain maps were not configured in the system.
Enhanced Ground Proximity Warning System (EGPWS)
The onboard terrain awareness system that provided aural 'PULL UP' warnings, though too late to prevent impact.
Interesting Facts
- 01The aircraft's GNSS position was erroneous by approximately 15 nautical miles at the time of the approach.
- 02The ATC Minimum Safe Altitude Warning (MSAW) system had not been configured with terrain data since its installation in 2015.
- 03Neither pilot was wearing a headset or boom microphone, contrary to the operator's manual for critical flight phases.
- 04The aircraft had undergone a minor calendar inspection only two days before the accident.
- 05The flight crew consisted of a highly experienced Captain (14,956 hours) and a relatively inexperienced First Officer (524 hours).
- 06The Minimum Sector Altitude (MSA) in the area was 8,500 feet, while the ATC surveillance minimum was 6,000 feet.
- 07The aircraft carried 7 crew members and 3 passengers (staff from the Directorate General of Marine and Fisheries Resources Surveillance).
Safety Actions & Advisories
SE-DJPU 2/2026
The DGCA issued a circular requiring all flight crews to strictly adhere to minimum safe altitude rules and TAWS response procedures.
SE-DJPU 4/2026
The DGCA mandated that crews verify their position using conventional navigation aids whenever GNSS degradation is detected.
ATC Audit
Regional offices were directed to audit ATC units and verify that MSAW datasets are correctly configured for local terrain.