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The takeoff safety speed. It is the lowest indicated air speed at which the directional control and the height can be maintained with one engine inoperative. This is the minimum control speed with an added safety margin to allow for the following factors, which could apply if an engine fails during or immediately after takeoff: (i) the element of surprise and reaction time; (ii) the failure of the critical engine (i.e., the port engine); (iii) the landing gear is down, the flaps are in the takeoff position, and the propeller is windmilling; and (iv) a pilot of average strength and ability. The airplane should reach V2; at the screen after an engine failure at V1 and climb out to 400 ft (120 m) altitude without the speed falling below V2;. In this process, the wings should be level and the angle of bank should not exceed 5°. V2 should be at least 1.3 times a 1 g stalling speed in the takeoff configuration.