What happened
On the night of 16 October 2024, a Boeing 737-800, registration PK-GMP, arrived at Kualanamu International Airport from Jakarta. The flight, operated by PT Garuda Indonesia, carried 102 passengers and seven crew members. After landing on Runway 2 and taxiing to Parking Stand W29, the aircraft came to a stop at its designated position.
Simultaneously, a Lavatory Service Truck (LST) was parked in a nearby equipment staging area. The operator had left the LST engine running and the transmission in neutral, relying on the parking brake and a wheel chock for stability. As the aircraft approached the stand, the LST began to move independently toward the aircraft. Upon the aircraft's arrival at the stand, the LST struck the tail section of the Boeing 737-800. While the collision caused damage to both the aircraft and the service truck, there were no injuries to any personnel or passengers.
The investigation
The KNKT investigation focused on why the LST moved without driver intervention. Investigators examined CCTV footage, flight data recorder (FDR) logs, and maintenance records for the ground support equipment. The inquiry scrutinized the serviceability of the LST's braking system, the maintenance practices of the ground handling provider, and the oversight procedures used by the airport operator and the civil aviation authority.
Findings
- The LST was operating with an unserviceable parking brake.
- Maintenance and daily inspections incorrectly assessed the vehicle as serviceable because it was assumed that a wheel chock could safely substitute for a functional parking brake.
- The movement was triggered by a combination of the LST's engine vibration, the downward slope of the parking surface, and the suction effect created by the aircraft's engines as it taxied nearby.
- The placement of the wheel chock was likely improper, potentially due to operator fatigue during late-evening shifts.
- Existing regulations allowed for the use of wheel chocks as a replacement for parking brakes, creating a safety loophole.
Safety action
The KNKT issued several recommendations to prevent a recurrence:
- PT Gapura Angkasa should implement a verification mechanism for proper wheel chock placement.
- PT Angkasa Pura Aviasi must improve supervision to detect motorized equipment operating with faulty brakes.
- PT Garuda Indonesia should enhance its Station Safety Audits to effectively identify serviceability issues in ground equipment.
- The Directorate General of Civil Aviation should review regulations to remove contradictory requirements regarding parking brakes and chocks, and include ground support equipment operations in its safety oversight program.