What happened
On February 16, 2022, at approximately 15:12 local time, a Swearingen Merlin SA-226-AT, registration HK-5225, was engaged in an air ambulance operation at Gustavo Rojas Pinilla Airport in San Andrés, Colombia. After successfully completing a flight from Barranquilla, the crew prepared for a return leg to Medellín to transport a patient.
While taxiing toward runway heading 06 via taxiway Bravo, the aircraft traveled approximately 200 meters before experiencing a sudden deviation toward the left side of the runway centerline. The crew attempted to correct the trajectory and maintain the aircraft on the pavement, but the aircraft exited the runway into the safety area. As the aircraft moved onto the grass, the crew applied the brakes, but the reduced friction on the grassy surface rendered the braking ineffective. The aircraft continued its leftward path until the nose section struck a concrete perimeter wall, resulting in substantial damage to the airframe. All 6 occupants (two pilots and four passengers) were evacuated safely and sustained no injuries.
The investigation
The Colombian investigation authority (DIACC) examined the aircraft's maintenance records, the crew's performance, and the operational environment. The investigation confirmed that the aircraft was airworthy and the crew was technically and physically fit for duty.
Investigators analyzed the aircraft's nose wheel steering (NWS) system and the taxi speeds recorded. While the aircraft's operating manual did not specify a maximum taxi speed, the maintenance manual explicitly limits taxiing to no more than 10 knots (18.5 km/h). The investigation determined that the aircraft was taxiing at a much higher speed, estimated at approximately 36 knots, at the time of the loss of control.
Findings
- The primary cause of the runway excursion was the loss of directional control due to exceeding the manufacturer's maximum allowable taxi speed.
- The crew may have failed to complete the complex nose wheel steering (NWS) checklist prior to taxiing, which could have prevented the steering from being securely engaged.
- There was evidence of self-imposed pressure on the crew to complete the scheduled medical mission quickly.
- The operator lacked standardized operating procedures (SOPs) regarding taxi speed limits and specific taxiing precautions.
- Contributing factors included potential misuse of the NWS system at high speeds, a lack of situational awareness, and inadequate application of Crew Resource Management (CRM) during a routine ground maneuver.
- The organizational structure, where the aircraft owner directly managed flights and crews, hindered operational standardization and safety oversight.