Abstract: The invention relates to a path or road barrier for vehicles, having a foundation which can be inserted into a depression of the driving surface and in which a recess is located. A bollard barrier part (30) is arranged in the recess of the foundation (10), and the path or road barrier is to prevent vehicles with a preferred travel direction in particular from passing through, said travel direction being oriented against the bollard barrier part (30) as the impact direction (15). The bollard barrier part (30) is made of two or more panels (31, 32, 33, 34) which can be handled separately from one another, said panels (31, 32, 33, 34) being arranged parallel to one another. The impact direction (15) is oriented against an impact face (35) of the bollard barrier part (30), said impact face being arranged perpendicularly to the panels (31, 32, 33, 34).

Abstract: A method of operating a rotorcraft collision avoidance system is provided. The method includes determining a unique characteristic of a detected rotorcraft, determining the actual length of a first rotor based at least in part on the determined unique characteristic of the rotorcraft, locating a major axis of the first rotor of the rotorcraft from a perspective of a home unit, from the perspective of the home unit, determining an angular extent of the major axis of the first rotor, and determining the then current distance from the home unit to the rotorcraft based at least in part on the determined actual length of the first rotor and the corresponding angular extent.

Abstract: A method of operating a rotorcraft collision avoidance system is provided. The method includes determining a unique characteristic of a detected rotorcraft, determining the actual length of a first rotor based at least in part on the determined unique characteristic of the rotorcraft, locating a major axis of the first rotor of the rotorcraft from a perspective of a home unit, from the perspective of the home unit, determining an angular extent of the major axis of the first rotor, and determining the then current distance from the home unit to the rotorcraft based at least in part on the determined actual length of the first rotor and the corresponding angular extent.

Abstract: A method of operating a rotorcraft collision avoidance system is provided. The method includes determining a unique characteristic of a detected rotorcraft, determining the actual length of a first rotor based at least in part on the determined unique characteristic of the rotorcraft, locating a major axis of the first rotor of the rotorcraft from a perspective of a home unit, from the perspective of the home unit, determining an angular extent of the major axis of the first rotor, and determining the then current distance from the home unit to the rotorcraft based at least in part on the determined actual length of the first rotor and the corresponding angular extent.