What happened
A scheduled flight traveling from Santiago de Cuba-Antonio Maceo Airport toward Havana experienced a catastrophic loss of control during its ascent. The twin engine aircraft was operating a service that included an intermediate stop in Santiago de Cuba, carrying 61 passengers and 7 crew members.
After departing at 16:44 local time, the flight crew received clearance to climb to 18,000 feet, followed by an increase to 20,000 feet at 17:36. During this climb, the aircraft's speed decreased from 196 knots to 176 knots as the Total Air Temperature fell from +3°C to -1°C. At 17:44, while maintaining FL200, an icing caution light and chime activated on the instrument panel, followed shortly by the illumination of the Angle of Attack (AOA) light.
In response to the icing, the crew activated the anti-icing systems and requested a descent to FL160 from Havana Control. Due to conflicting traffic 30 miles ahead, the controller provided vectors that changed the flight path from 295° to 330°. At 17:49, while flying at 156 knots, the aircraft began a right bank before experiencing sudden oscillations between left and right banks. The plane then entered a steep nose-down attitude with a 90-degree left bank. Despite efforts by the crew to maintain control, the aircraft lost altitude and crashed into wooded, hilly terrain. All 68 fatalities were recorded.
Findings
The investigation concluded that the flight was operating normally until it encountered extreme meteorological conditions. These conditions led to severe ice accumulation on the airframe at 20,000 feet. This environmental factor, combined with errors made by the crew while managing the situation, resulted in the accident.