What happened
On October 29, 2020, at approximately 11:38 local time, an Airbus A320-232 was parked at Gate 20B of Arturo Merino Benítez International Airport (SCEL) in Pudahuel, Chile. The aircraft was in the middle of passenger disembarkation when the flight crew and passengers felt a significant impact.
The collision occurred when another aircraft, an Airbus A3/20-214, was being moved by a towbarless tractor (monitor towing) from a maintenance area toward Gate 21. During the maneuver, the wingtip of the towed aircraft struck the left wingtip of the stationary Airbus A320-232. While the 187 passengers and 7 crew members on the stationary aircraft were uninjured, both aircraft sustained structural damage to their wingtip fences (sharklets), requiring component replacement and specialized inspections.
The investigation
DGAC Chile investigators examined the movement logs, radio communications, and physical evidence at the scene. The investigation reviewed the airport's operational data, including the Airport Operation Data Base (AODB), which showed that the movement of the Airbus A320-214 had been programmed for Gate 21B—a gate specifically designated for narrow-body aircraft—24 hours in advance.
Investigators also analyzed the towing driver's personal notes, which indicated an instruction to move the aircraft to Gate 21 instead of 21B. The investigation looked into the presence of ground support, noting that no wingwalkers were assigned to the maneuver, and reviewed the visibility conditions, which were excellent with unlimited visibility at the time of the event.
Findings
- The primary cause of the incident was the impact of the towed aircraft against the left wing of the stationary Airbus A320-232 while being moved to the wrong gate.
- The towing operator entered the area for Gate 21 erroneously, despite having documented knowledge of parking risk maps that restrict certain gates to specific aircraft types.
- The towing operator failed to correctly use visual references, such as the safety cones placed on the stationary aircraft's wingtip or the painted overlap area on the pavement, leading to a misjudgment of the clearance.
- The towing driver recorded an instruction to proceed to Gate 21 in their notebook, which contradicted the official movement plan and the radio instructions provided by the ground control operator.
- The maneuver was performed without the assistance of wingwalkers, as this service was not included in the agreement for that specific flight.
Safety action
To prevent recurrence, the investigation suggested that the aircraft towing company evaluate the following:
- Implementing digital devices for towing personnel to prevent manual transcription errors regarding gate assignments.
- Assessing the necessity of using wingwalkers based on the risk levels of specific parking areas.
- Coordinating with the airport concessionaire to utilize existing surveillance technology and operations center personnel to identify and correct improper gate entries in real-time.