Incident Overview
On an unspecified date, an Air Sénégal Twin Otter, operating an uneventful flight from Saint Louis, was cleared to descend to Dakar-Yoff Airport and instructed to maintain 3,000 feet over the YF VOR. Simultaneously, an NAMC YS-11, registered C5-GAA, departed Dakar-Yoff on a scheduled flight to Banjul carrying 34 passengers and a crew of four. Its pilots were instructed to climb via radial 140 and maintain 2,000 feet while over the YF VOR.
Collision
When both aircraft reached the YF VOR, they collided. The NAMC YS-11 sustained a partially torn left wing, but its crew managed to return to Dakar and land safely. In contrast, the Twin Otter entered an uncontrolled descent and crashed into the sea a few kilometers offshore, resulting in the deaths of all three occupants.
Investigation Findings
The official investigation determined that both crews failed to respect their assigned altitudes, leading to the collision. At the time of the accident, the Twin Otter was approximately 100-300 feet too low, while the NAMC YS-11 was approximately 700-900 feet too high.