The De Havilland Dh.106 Comet was the first commercial Jet Line. It was intended for Medium and short-hault routes. The first prototype first flew on the 9th January 1951. Gradually, the manafacture switched to an output of more powerful "Comet-1A" and in conjunction with it started the development and manufacture of more perfect "Comet-2" with Rolls Royce Avon engines and "Comet-3" with more powerful Avon 16 engines. At the second part of 1955, the BOAC aircraft company decided to pace zn order for 19 completly modified and improved "Comet-4" for exploitation in transatlantic, african and eastward routes. The first 'Comet-4' made its first flight on the 27th April 1958. In the 1950s and 1960s the "Comet-4", the 4B and the 4C successfully serviced airlines all over the world.