What happened
On the night of January 24, 2023, at approximately 22:23 local time, a Piper PA-31T was performing taxi operations at Carriel Sur Aerodrome (SCIE) in the Bío-Bío Region of Chile. The aircraft, operating as an air ambulance, was preparing for a flight to Arturo Merino Benítez International Airport (SCEL) carrying a medical team and a patient.
While taxiing along taxiway "Alpha" toward runway 20, the aircraft inadvertently drifted to the left. The crew was unable to regain directional control, causing the aircraft to exit the taxiway. During the excursion, the left main landing gear struck a ditch located 35 meters from the taxiway centerline. The crew immediately shut down the engines to facilitate the safe evacuation of the patient and medical personnel. While the aircraft sustained significant damage, there were no injuries to the two pilots, the medical team, or the patient.
The investigation
DGAC Chile investigators examined the mechanical, operational, and environmental factors surrounding the excursion. Technical inspections of the Piper PA-31T revealed no mechanical discrepancies in the nose wheel steering, braking systems, or structural integrity prior to the event. Maintenance records indicated the aircraft had undergone a 100-hour inspection recently and was in a satisfactory state of airworthiness.
The investigation also analyzed the physical evidence at the scene, noting tire skid marks on taxiway Alpha that indicated a progressive leftward drift. Investigators confirmed that the lighting and markings on the taxiway were fully functional and that weather conditions were not a contributing factor. Furthermore, radio communications between the tower and the pilot showed no prior reports of directional control issues during the taxi sequence.
Findings
- The primary cause of the incident was the loss of directional control during taxi, which led to the aircraft deviating from the taxiway.
- The speed at which the aircraft was taxiing prevented the crew from effectively correcting the inadvertent leftward deviation.
- The presence of a ditch outside the safety strip provided the obstacle that trapped the left main landing gear.
- Human factors analysis suggested that "rushing," likely due to the urgency of the air ambulance mission and the pressure to meet departure schedules, may have contributed to the error.
Safety action
- The DGAC recommended that general aviation pilots maintain taxi speeds that allow for effective directional control under all circumstances.
- It was suggested that flight operators review aircraft operating manuals to standardize safe taxi speeds for various scenarios.
- Recommendations were made to improve cockpit resource management by clearly distributing tasks and responsibilities between crew members during night operations.