History of Flight
On December 31, 2017, about 1156 central standard time, a Cessna 208B airplane, Costa Rican registration TI-BEI, crashed while maneuvering after takeoff from runway 3 at Islita Airport (MRIA), near Corozalito, Costa Rica. The 2 flight crewmembers and 10 passengers were fatally injured. The airplane was destroyed by impact forces and post-impact explosion and fire. The airplane was registered to and operated by Nature Air, San José, Costa Rica, as a commercial charter flight operating under Costa Rican flight regulations. Visual meteorological conditions prevailed for the flight, which was originating at the time of the accident with an intended destination of Juan Santamaría International Airport (MROC), San Jose, Costa Rica.
The accident airplane was the second of a flight of two Cessna 208B airplanes transporting hotel guests from MRIA to MROC. The first airplane departed using runway 3 and made a right turn to the east through a pass. The accident airplane took off about 15 minutes later. According to a hotel employee at the airport, the accident airplane did not make the same right turn but continued on runway heading. A ground-based surveillance video captured the takeoff and accident sequence, showing the airplane climbing north on runway heading then starting a left turn. During the turn, the bank angle steepened and the airplane descended into terrain.
The airplane's flightpath followed a valley with rising terrain on either side; the valley turned left and continued rising until reaching a mountain. When heading north from the airport, there was no exit from the valley. The airplane impacted terrain on the northwest side of the valley about 0.4 statute miles from the departure end of runway 3.
Personnel Information
The 52-year-old captain held a Costa Rican commercial pilot certificate with single-engine land, multiengine land, instrument, and flight instructor ratings, and an ATP certificate from the FAA. He held US and Costa Rican first-class medical certificates issued November 8, 2017, with no limitations. His resume indicated 14,508 hours total flight experience, including 11,587 hours in Cessna 208B airplanes. Training documents showed ground training at Nature Air beginning October 2017, but no records of completed flight training, check flights, or initial operating environment training were provided.
The 26-year-old first officer held a Costa Rican commercial pilot certificate with single-engine land, multiengine land, and instrument ratings, and a Costa Rican first-class medical certificate issued June 27, 2017, with no limitations. Her resume indicated 453 hours total flight experience, including 370 hours in single-engine airplanes and 83 hours in multiengine airplanes. Training documents showed she received ground training at Nature Air in October 2017.
Aircraft Information
The accident airplane was a Cessna 208B Caravan, serial number 208B0900, high-wing, single-turboprop, fixed tricycle landing gear. It was configured to seat 12 passengers plus 2 crew. The airplane was powered by a 675-horsepower Pratt & Whitney Canada PT6A-114A turboprop engine. The airframe had accumulated 12,072.9 hours total time and 20,813 cycles as of December 30, 2017. The engine had accumulated 3,271.5 hours and 4,637 cycles since new. The airplane was maintained in accordance with an Approved Aircraft Inspection Program.
Meteorological Information
Weather at a station about 25 miles east of the accident site at 1200 recorded temperature 32°C, relative humidity 55%, and east wind at 4 knots gusting to 12 knots. Wind models indicated about 5 knots from the northeast. The airport had two windsock structures but neither was equipped with a windsock at the time of the accident. The witness at the airport estimated wind between 10 and 15 knots.
Wreckage and Impact Information
The wreckage was removed before NTSB arrival. The accident site was on a heavily wooded hillside about 0.4 sm northeast of the departure end of runway 3 at elevation 238 ft msl. Trees displayed clean diagonal cuts consistent with propeller contact. The airplane impacted in a near-vertical attitude. Postcrash fire was evident. The wreckage was severely fragmented and burned; flight control cable continuity could not be confirmed but separations were consistent with tensile overload or cutting.
Additional Information
A passenger's friend reported text messages indicating the airplane had been involved in a bird strike during its arrival to MRIA. Photographs showed left wing leading edge damage near the landing light. The damage was localized and would not have adversely affected flight characteristics or controllability. The witness stated the captain contacted maintenance and waited for a release before proceeding, which delayed departure by about 15 minutes.
Medical and Pathological Information
Complete autopsy reports were not available, but summary findings listed traumatic injuries as the cause of death for all occupants. A limited set of medical information for the captain included a single page regarding three visits for psychiatric evaluation in November and December 2011, with diagnoses of Type I bipolar disease, attention deficit disorder with memory problems, superior intelligence, and normal thyroid function. Treatment was begun with Seroquel. No further information on diagnosis confirmation or treatment effectiveness was available. The captain reported no medical conditions, medications, or visits to health care providers during his most recent US aviation medical exam in November 2017, and was issued a first-class medical certificate without limitations.
Tests and Research
Evaluation of surveillance video estimated the airplane's groundspeed at 68±3 kts shortly after takeoff, climbing about 715 ft/min. Later, it was descending about 1,510 ft/min with groundspeed 82±4 kts, reaching a bank angle of 75° right-wing-up. The POH lists stall speeds at gross weight and 60° bank as 110 kcas (0° flap) and 98 kcas (20° flap).
Weight and balance calculations determined a takeoff weight range between 7,740 lbs and 8,594 lbs to remain within CG limits and have adequate fuel. Takeoff performance: at gross weight, 30°C, 10-kt tailwind, ground roll required about 2,235 ft. Climb performance scenarios showed that a straight-out departure and a left turn following the valley might not have sufficient climb gradient to clear terrain, while the path used by the previous airplane provided positive margins.