1. Field of the Invention
This invention relates to a system for aiding the movement of moving units in group formation. More particularly, this invention relates to a method and apparatus for directing the flight of aircraft (especially helicopters) in formation flying.
2. Description of the Prior Art
The transfer of a large number of helicopters from a given base to a distant base takes a long time due to the fact that the helicopters are transferred one by one. This slow transfer of helicopters is necessary as a safety measure due to the fact that the transfer often occurs under conditions of poor visibility, e.g. in the presence of fog or at night.
The helicopters to be transported are typically grouped into formations of five to ten helicopters each. Each such formation typically involves a guide helicopter called the "leader" and the other "slave" helicopters. The slaves fly behind the leader in given positions relative to the leader and relative to each other. The leader flies in such a way as to maintain a given spacing between that leader's formation and other formations.
Within each formation, the relative positioning of the helicopters is controlled to avoid collisions. Although it is desirable to maintain tight formation spacing in order to allow the transfers to be carried out in a small amount of time, formation spacing must be loose enough to account for anticipated deviations of individual helicopters from their desired positions. Therefore, due to the recognized danger and due to the difficulty of maintaining controlled spacing, group formation transfers now are generally carried out under conditions of good visibility and in visual flight.
An object of this invention is to provide a method and an apparatus for facilitating a rapid and safe transfer of a number of helicopters by allowing multiple groups of helicopters to travel simultaneously in safe formations. Another object of the invention is allow formations of helicopters to fly safely in conditions with poor visibility. Another object is to provide a system wherein the configuration of the formation varies over time in a predetermined way.