The de Havilland Comet airliner entered service with BOAC on 2 May 1952, when it launched the world’s first jet commercial airline service with scheduled flights to South Africa. The Comet was a low wing, all metal, four-engined jet aircraft with many innovative design features including a swept leading edge, integral wing fuel tanks and four-wheel bogie main undercarriage units. Two pairs of de Havilland Ghost 50 turbojet engines were buried in the wings close to the fuselage. The Comet was about 50% faster than rival aircraft and on some routes cut journey times by as much as half. Its relatively simple, fuel efficient engine with low maintenance costs and little vibration could fly above any bad weather which traditional piston aircraft would have to fly through. It soon became a big hit with passengers including Queen Elizabeth the Queen Mother and in its first year carried 30,000 passengers. The Comet 1 was dogged by bad luck. Metal fatigue, about which little was known, caused the crash of two B.O.A.C. Comets and the type's certificate of airworthiness was withdrawn. When the cause of the crashes was established, de Havilland set about re-designing the Comet and, eventually, produced the larger Comet 4. The Comet served with the world's major airlines with the type 4B being released for British European Airways.