Chronograph Type XX and the retour en vol device.Louis Breguet (1880-1955) developed a keen interest in aeronautics, conquering the air in 1907 in his gyroplane, the first helicopter in the world to leave ground with a passenger. Soon afterwards was established the ?Louis Breguet? aircraft industry. Meanwhile, the watchmaking firm Breguet, saw a new opening and began producing watches for pilots or to be fitted on aircrafts. ?Montres Breguet? therefore introduced chronographs with registers and tachometric scale and among their first clients wre, of course, the American Air Force in 1918 and the ?Louis Breguet? aircraft industry in 1922. The number of clients soon increased, especially in the fifties.The chronograph wristwatch Type XX, launched in 1954, became the most successful and most famous post-war aviator?s watch. Though at first these watches were intended for the strict use of air forces, Breguet, in the 70?s, launched the second generation of these, edited for civilianuse. Breguet?s third generation of Type XX Aéronavale is now on the market.The peculiarity of the Type XX chronograph is that it features the retour en vol, or ?instantaneous fly-back? device. This function highly appreciated by pilots and aeronautical authorities, was incorporated in all Type XX models and in chronographs to be fitted in aircraft dashbards. The retour en vol device is a great time saver, reducing three actions to one, since it allows the chronograph hand to return to zero by simply depressing the lower push-button; consequently, the chronograph hand,ack at zero, can restart immediately.