Investigation Summary
The flight was approaching Medan's Polonia International Airport under heavy smoke haze from forest fires. Due to a communication breakdown between the Air Traffic Controller (ATC) and the flight crew, there was confusion regarding the direction of a turn. The controller mistakenly identified the aircraft on radar and cleared it to descend below the minimum safe altitude while the aircraft was heading toward mountainous terrain rather than the runway path. The crew, disoriented by the haze and relying on conflicting ATC instructions, failed to notice they were flying into a mountain until the Ground Proximity Warning System (GPWS) sounded seconds before impact.
Final Conclusions
The crash was caused by a combination of ATC error, pilot confusion, and environmental factors. The controller gave instructions to a different flight but addressed them to GA152, and subsequently cleared GA152 to descend to 2,000 feet—well below the 7,500-foot mountain peaks in the area. The crew's failure to verify their position relative to the terrain in low visibility led to the CFIT.
Video Analysis
The Deadliest Crash in Indonesia | Garuda Indonesia Flight 152 — A detailed look at how communication errors and thick volcanic/forest fire haze led to the tragic crash of an Airbus A300.
Watch on YouTube ↗If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
GPWS
Ground Proximity Warning System; it alerted the crew 5 seconds before impact, but the terrain was too steep to avoid.
Radar Vectoring
The ATC used radar to guide the plane, but misidentified the aircraft's position relative to high terrain.
Interesting Facts
- 01Deadliest aviation accident in Indonesia's history.
- 02The region was covered in thick smoke from massive forest fires in Kalimantan.
- 03The ATC controller was handling multiple aircraft and confused GA152 with another flight (Merpati 241).
- 04The aircraft was an Airbus A300B4-220, which did not have the most modern terrain mapping displays of the era.
- 05The crash occurred just 20 miles from the airport.
Safety Actions & Advisories
ATC Protocol Revision
Source ↗Procedures for handovers and altitude clearances in the Medan airspace were tightened to prevent descent below Minimum Safe Altitude (MSA).
Installation of MSAW
Minimum Safe Altitude Warning (MSAW) systems were prioritized for installation in Indonesian ATC centers to alert controllers when aircraft are too low.