A head-up display system includes means generating a pitch ladder pattern having pitch bars which are straight lines with a central gap, the pitch bars representing climb angles being solid lines and the pitch bars representing dive angles being dashed lines, the pattern having a scale factor which is unity in a central region and which increases smoothly from the central region towards the extremes of the pattern, characterised in that: a) the central bar representing level flight is considerably longer than any other bar, and the lengths of the bars decrease according to a relationship with their displacement from the central bar; b) the zenith or 90.degree. climb angle is indicated by a distinctive star symbol and the nadir or 90.degree. dive angle is indicated by a distinctive earth symbol, and c) the pattern has two inner regions on either side of the central region, and two outer regions between the inner regions and zenith and nadir respectively, and the graduation intervals in the outer regions are considerably greater than the graduation intervals in the inner regions, so that the first graduation interval in each outer region is considerably wider than the last graduation interval in each inner region, thus providing distinctive indications of the angles at which the inner regions end and the outer regions begin.
A system of pitch attitude symbols, which can be generated by a head-up display unit of an air vehicle, is provided. The system of pitch attitude symbols can be displayed by the head-up display as a virtual image in the direction of flight, behind the cockpit screen in a focal plane in front of the background. An unequivocal system of pitch attitude symbols is provided for the pilot, for a display area of an HUD, which display area is arranged below the natural horizon during neutral flight attitude of an air vehicle. Within the focal plane, the system of pitch attitude symbols comprises at least one pitch attitude representation area, arranged in perspective, which pitch attitude representation area can always be arranged parallel to the surface of the earth. The rear edge of the pitch attitude representation area is tiltably fixed in a rear edge axis and, depending on the pitch attitude of the air vehicle, the pitch attitude representation area can be tilted on the focal plane. The front edge shows the pitch attitude in relation to an angular-degree scale.
