By 1952, the British state airline BOAC had introduced the Comet into scheduled service. While a technical achievement, the plane suffered a series of highly public failures, as the shape of the windows[citation needed] led to cracks due to metal fatigue. The fatigue was caused by cycles of pressurization and depressurization of the cabin, and eventually led to catastrophic failure of the plane's fuselage.[citation needed] By the time the problems were overcome, other jet airliner designs had already taken to the skies.