Giant Congo Snake?
Colonel Remy Van Lierde born 14 August 1915, died 8 June 1990 was a Belgian pilot who served during World War II in the Belgian and British Air Forces and achieving the RAF rank of Squadron Leader. He was made Deputy Chief of Staff to the Ministry of Defence in 1954. In 1958 he became one of the first Belgians to break the sound barrier while test flying a Hawker Hunter at Dunsfold Aerodrome in England. He returned to the Belgian Air Force after the war and went on to hold several important commands before retiring in 1968. . In 1959, as full Colonel, he commanded the air base at Kamina in the Belgian Congo.
Not a person who would ruin their reputation with a hoax then.
He was returning from a mission in the Katanga region of the Belgian Congo in 1959 and was flying over the jungle in a helicopter when he spotted a giant snake, “very dark green with his belly white,” which he estimated to be 15 meters (50 ft) in length.He related that the serpent reared up as though it was about to attack the helicopter. The head was 3-feet( 1 meter) wide and 2 feet wide, and that the jaws were of a triangular shape.His companion managed to get a photograph of the beast, but the picture is blurry and doesn’t indicate the scale, so it has been dismissed by sceptics.Van Lierde insisted that the monster was a true giant and “could easily have eaten up a man” if it had wanted to.
It seems logical Van Lierde did come across large snake, perhaps even a new species, but could have overestimated its size. Its difficult when one is caught off guard by something unusual to think clearly. Snakes do grow to over 20 feet ,some even 30 feet and it may have been one of these he flew over.Plus if the snake was in water,water distorts size and shape from some angles. I doubt he would risk his reputation on a hoax and genuinely he believed he saw a giant snake.
Here is a Congo snake that grows to ten feet but the angle of the photograph makes it appear much larger: