Abstract: As a method and device for representing the horizon on board an aircraft, there is displayed on the cathode tube of a collimator an image comprising a circle of small size inside which there are, on the one hand, a horizon line inclined to the horizontal by an angle equal to but opposite the rolling angle of the aircraft, the horizon line being remote from the center of the circle by a distance which is a function of the pitching angle in the upward direction when the aircraft is diving and in the downward direction when the aircraft is pulling the nose up, and which delimits to zones of different brightness and, on the other hand, a point representing a pole situated on the median line of the horizon line at a distance from the latter corresponding to a pitching angle of 90.degree.. A "head up" type control system is essentially provided.