In 1959, Remy Van Lierde, a Colonel in the Belgian Air Force, commanded the air base at Kamina in the Belgian Congo. In the Katanga region of the Democratic Republic of the Congo, returning from a mission by helicopter, he claimed to have seen an enormous snake as he flew over the forests. He described the snake as being close to 50 feet in length, with a triangular head 2 feet wide by 3 feet long which, if his estimations were accurate, would earn the creature a place among the largest snakes ever to have existed.
Colonel Van Lierde described the snake as having dark green and brown top-scales and a whitish coloured underside.
Upon sighting the reptile, he then had the pilot turn around and make another pass, at which point the snake reared up the frontal ten feet of its body as if to strike, giving him the opportunity to observe its underbelly. However, after flying so low that Van Lierde believed it to have been within striking distance of his helicopter, he ordered the pilot to resume his journey, and so the creature was never properly documented, although some reports suggest that an on-board photographer managed to snap a shot of it.
Possible ExplanationIt is believed to be either a surviving Titanoboa or perhaps a new species of snake. If anything, large species of snakes primarily come from the constrictor family (which includes pythons and boas) and those of the anacondas. Maybe the snake is an undiscovered specie of the world's largest snake.
An interview with Colonel Van Lierde about the sighting can be found here.