Abstract: 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.