Radar wake vortex measurements at F and I band

All aircraft generate vortices in their wakes, which are created by the wings as the aircraft produces lift. The wakes consist of two counter-rotating masses of air that are cylindrical in shape and are a potential hazard to a following aircraft. When encountering a vortex a severe roll that may not be possible to control, can be induced, with the possible catastrophic results. The most hazardous situation is when a small aircraft is following a larger one on landing approach. Aviation regulations specify minimum separations between different types of aircraft when they are receiving an Air Traffic Control service, so as to ensure that a vortex does not present a hazard to following aircraft. There are two weather conditions that particularly concern ATC authorities. First, those where the vortices persist, and second those which lead to a rapid dispersion of the vortices which could enable the minimum separation between aircraft to be significantly reduced. The successful reduction in separations could improve runway capacity and contribute to the growth in air transport. As yet there is no reliable all weather method in operation that can determine whether the vortices generated by an aircraft have dispersed, and so, there is an important requirement for a technique or techniques to be developed that can be reliably employed to detect the presence of vortices in the vicinity of airports. This paper describes work undertaken at the GEC-Marconi Research Centre to investigate the feasibility of detecting aircraft wake vortices using a microwave radar