A head-up display for indicating the attitude and flight-path angle vertically, the attitude in roll and preferably the heading attitude and heading track angle of a vehicle, preferably an air vehicle, which in addition to the inertial navigation (5) for determining said attitudes and angles comprises a transparent but partly reflecting plate (10), a so-called "combiner glass" glass for projecting a corresponding display together with at least one symbol (14) of the x-axis of the vehicle. Particularly characteristic is that the head-up-display is arranged to show the display (12) as at least a portion of the inside of a space-stable sphere with its center in said vehicle, the display being provided with latitude circles (15, 16, 19, 20) and preferably meridian markings (18).

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.

An apparatus for determining the bank angle of a moving aircraft includes a receiver for receiving navigational signals from NAVSTAR/GPS satellites in orbit about the earth, a signal processor for demodulating the satellite navigational signals, an arrangement for determining aircraft speed based on the navigational signals, an arrangement for determining the rate of change of the aircraft track heading from the navigational signals, an arrangement for determining the bank angle of the moving aircraft from the aircraft speed and the rate of change of track heading wherein the aircraft bank angle is inversely proportional to the aircraft speed and directly proportional to the rate of change of track heading.

The invention relates to a process for the display on a screen on board an aircraft of flying aid symbols. On the basis of information supplied by an inertial system and ground beacons processed by an on board computer, the process consists of displaying on an on board screen (EV) symbols more particularly representing the wings of the aircraft (A1, A2), the model of the aircraft (CP), its speed (V), the tendency to acceleration and deceleration (AD1, AD2), a flight path prediction (PT), the artificial horizon (H), the roll angle (.phi.), the sideslip (AL) and the total energy (ET1, ET2). It also consists of displaying the flight path to be followed in perspective (P1, P2, S3, S4, S5) and in projection (S'1 to S'5) on the plane of the runway. Any flight path segment during passage, as well as the segment following the latter are displayed in parallelepipedic form (P1, P2) in perspective. A final segment preceding the touchdown point of the wheels on the runway is displayed in the form of a pyramid (P3) in perspective. A display also takes place of the runway (P) and a grid (M1, M2, PE1, PE2) superimposed on said runway, in perspective.

A system is provided which permits a display of ground conditions to the pilot through the use of a forward looking sensor set and uses signals generated from the aircraft to simulate ground aid signals which are used for automatic landing of the aircraft. General flight path angle and course aim point corrections are made from the cockpit of the aircraft and are adjustable as the flight progresses. Most of the systems today that have fixed path capability to ground intercepts are based on ground installed equipment. This system can establish the inertial flight path track internally to the aircraft and provides an automatic landing system which allows the pilot to concentrate on the visibility of the forward scene to confirm the safe progress of the landing.