Abstract: A mass memory stores a data base representing at least a substantial part of the terrestrial globe, in accordance with a grid configuration on several levels, said grid configuration being in particular more precise in the vicinity of an airport. Status indications are received representing the position of the aircraft with two horizontal components, and the altitude, and the velocity and acceleration vectors of the aircraft, as well as control indications coming from the flight deck. In accordance with the horizontal components of the position of the aircraft, a temporary local map is transferred into a fast access memory, on the basis of which map, an altitude envelope of the terrain is established in the zone where the aircraft is travelling. Anticollision processing make it possible to establish an alarm if the relation between a protection field and the altitude envelope meets a first condition which is defined at least partly by the control indications.

Abstract: The so-called flight path of an aircraft is defined in the form of a set of successive target points (B.sub.i -1, B.sub.i, B.sub.i +1) with a target circle (CB.sub.i) associated with each target point. A navigation envelope (DN) is determined in she direction to this target, and a guidance envelope (DH) is determined in the direction of the next target, for each target point. Normally, the aircraft is in the navigation envelope, and reenters the guidance envelope, then the target circle (B.sub.i) after which it heads in the direction of the navigation envelope associated with the next target. In the contrary case, a mandatory switching envelope (DCF) determines the instant when the aircraft is to orient itself on the next target (B.sub.i +1).

Abstract: The surveillance radar device comprises, in combination, a fixed antenna for providing electronic scanning of space in bearing in the horizontal plane, a transmit source and microwave frequency transmit/receive means with a circulator, a transmit channel, a receive channel and means for subdividing the receive channel into a sum signal and at least one difference signal. A first and a second receiver element with frequency change respectively receive the sum and difference signals, and provide numerically coded outputs. Processing means process numerical signals from the first and second receiver elements for the radar detection of objects in the zone under surveillance.

Abstract: A mass memory stores a data base representing at least a substantial part of the terrestrial globe, in accordance with a grid configuration on several levels, said grid configuration being in particular more precise in the vicinity of an airport. Status indications are received representing the position of the aircraft with two horizontal components, and the altitude, and the velocity and acceleration vectors of the aircraft, as well as control indications coming from the flight deck. In accordance with the horizontal components of the position of the aircraft, a temporary local map is transferred into a fast access memory, on the basis of which map, an altitude envelope of the terrain is established in the zone where the aircraft is travelling. Anticollision processing make it possible to establish an alarm if the relation between a protection field and the altitude envelope meets a first condition which is defined at least partly by the control indications.