Aerodynamic stall and terrain impact during commercial charter departure

12 fatalities • Punta Islita, Costa Rica • Takeoff (climb)

A commercial charter flight departed a non-towered airport in a valley and crashed into rising terrain following an improper departure procedure and an aerodynamic stall.

What happened

A commercial charter flight, carrying ten passengers, was departing from a non-towered airport situated in a valley surrounded by mountains. The departure airport featured a runway layout where runway 21 offered a path toward the ocean, while runway 3 required a specific flight path over lower terrain to clear the surrounding peaks. Approximately 15 minutes prior to the accident, a preceding aircraft successfully departed runway 3 by executing an immediate right turn to follow the low-altitude pass through the hills.

On the flight in question, the aircraft departed from runway 3 but maintained its runway heading instead of following the established terrain-clearing path. The aircraft then entered a left turn and descended into the mountains. Surveillance footage and witness accounts indicated that the aircraft reached a bank angle of approximately 75 degrees and slowed to a speed below the aerodynamic stall speed before the impact. There was no evidence of mechanical failure or engine malfunction, as the engine showed signs of producing power at the time of impact. The accident resulted in fatalities (as implied by the crash context, though specific counts were not provided in the source, the impact was fatal to the flight).

Findings

Investigations revealed that the crew failed to utilize the necessary eastern pass to avoid the rising terrain. While the pilot in command was experienced in the aircraft type, records indicated he had not completed all required training mandated by the operator's manual. Furthermore, the operator lacked a formal system for providing airport-specific training for locations with challenging terrain.

At the time of the accident, the airport lacked functional windsocks, leaving the crew without information regarding wind velocity. It is possible the crew chose runway 3 to avoid potential tailwind limitations, yet the aircraft's weight and balance at the time of departure likely left it with insufficient climb performance to clear the northern terrain. The crash was likely caused by the crew attempting a steep left turn to exit the valley, which led to an aerodynamic stall due to excessive bank angle and insufficient airspeed.

Probable cause

The flight crew failed to follow the established terrain-clearing departure path, leading to an aerodynamic stall during a steep turn into rising terrain.

Frequently asked questions

What happened in the 2017-12-31 Cessna 208B Grand Caravan accident near Punta Islita, Costa Rica?

A commercial charter flight departed a non-towered airport in a valley and crashed into rising terrain following an improper departure procedure and an aerodynamic stall.

Were there any fatalities in the 2017-12-31 Cessna 208B Grand Caravan accident?

The accident was fatal, resulting in 12 fatalities.

What aircraft was involved and where did it happen?

The accident on 2017-12-31 involved a Cessna 208B Grand Caravan, registration TI-BEI, operated by NatureAir, at Punta Islita, Costa Rica.

What was the probable cause of the accident?

The flight crew failed to follow the established terrain-clearing departure path, leading to an aerodynamic stall during a steep turn into rising terrain.

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