A Belgian helicopter pilot called Remy Van Lierde, took this photo during a patrol over the Congo in 1959. The snake he witnessed has been estimated to be anywhere from around 40-50 feet long.
It was described by the pilot as a dark shade of brown and green with a white coloured belly.
The jaws were of triangular shape. The pilot claimed the head was a massive 3 feet wide, adding that as he cautiously moved in lower for a closer inspection the snake raised itself in the air as high as maybe 10 feet, looking like it may attack the helicopter.