Factual Information
On 16 October 2024, a Boeing 737-800 aircraft registered PK-GMP, operated by PT Garuda Indonesia, was conducting a scheduled passenger flight from Jakarta to Medan. The aircraft landed at Kualanamu International Airport at 2113 local time and taxied to Parking Stand W29. On board were two pilots, five flight attendants, and 102 passengers.
At 2126 LT, while the aircraft was taxiing on Apron W and turning right into the parking stand, a Lavatory Service Truck (LST) parked in the Equipment Staging Area began moving without any external intervention. The aircraft had a ground speed of approximately 5 knots and engine N1 of about 21%, as recorded by the Flight Data Recorder. When the aircraft reached its parking position, the LST impacted the tail section of the aircraft. No persons were injured, but both the aircraft and the LST sustained damage.
Sequence of Events
The investigation determined that the aircraft was serviceable throughout the flight. The LST, however, had an unserviceable parking brake. During periodic inspections and daily checks, the assumption that a wheel chock could substitute for the unserviceable parking brake resulted in the vehicle being assessed as serviceable. On the day of the incident, the wheel chock was improperly placed.
The investigation noted that the combination of late-evening work and developing fatigue might have influenced the improper placement of the wheel chock. Additionally, the vibration from the LST engine running and the aircraft movement toward the parking stand, combined with the suction effect generated by the aircraft engine, contributed to the unintentional movement.
Conclusions and Contributing Factors
The KNKT concluded the contributing factors as follows:
- The assumption that an unserviceable parking brake could be replaced with a wheel chock resulted in the LST with an unserviceable parking brake being assessed as serviceable during periodic inspection and daily checks.
- The combination of late-evening work and developing fatigue might have influenced the improper placement of the wheel chock.
- The vibration from the LST engine running and the aircraft movement toward the parking stand, combined with the suction effect generated by the aircraft engine, led to the unintentional movement of the LST.
Safety Actions
Following the incident, PT Gapura Angkasa and PT Garuda Indonesia have taken safety actions as detailed in the report. Recommendations have been issued to PT Gapura Angkasa, PT Angkasa Pura Aviasi, PT Garuda Indonesia, and the Directorate General of Civil Aviation.