Accident Overview
A twin-engine aircraft operating a special flight from Dodoma to Dar es-Salaam, Tanzania, crashed after experiencing an in-flight disintegration. The aircraft was carrying nine members of the United Nations organization on a humanitarian mission in Tanzania, along with the pilot, for a total of 10 occupants.
Flight and Weather Conditions
While cruising at an altitude of 4,000 feet, the pilot encountered poor weather conditions including thunderstorm activity. While flying in clouds, the pilot suffered spatial disorientation and lost control of the aircraft.
Loss of Control and Structural Failure
During the uncontrolled descent, the aircraft experienced an overload failure and partially disintegrated before crashing in a pasture. The structural failure occurred as the diving speed exceeded the design limits of the aircraft.
Official Finding
According to the investigation, the accident was caused by midair disintegration owing to structure overload caused by diving speed in excess of the structural design limits. The rest of the fuselage and the remaining part of the empennage then floated downwards as the occupants were flung out of the cabin, some with the seats and seat rails.
Contributing Factors
The investigation reported several contributing factors: the penetration speed was not selected prior to entering the thunderstorm area; the pilot suffered spatial disorientation while flying in clouds; the aircraft was overloaded; and the onboard weather radar was unserviceable at the time of the accident.