To avoid this, Bertin, Developer of the aerotrain, has come up with an air-cushion system which assures a safe and soft landing. It comprises a platform on which the freight is loaded with, underneath, a series of ‘balloons’ supported by air cushions. These are fed from compressed air cylinders equipped with an altimeter valve which opens when the load is just over six feet from the ground. The platform then becomes a hovercraft, with the balloons reducing the deceleration as it touches down.