1. A UAV landing system, comprising:a landing pad defining a landing area for a UAV, the landing area comprising a target point for UAV landing or payload delivery;
a plurality of positioning radios positioned in a spaced apart relation and substantially equidistant from the target point, each positioning radio of the plurality of positioning radios including a radio transmitter wherein each radio transmitter is configured to transmit a ranging signal to an approaching UAV; and
a position determination and aircraft navigation system at the incoming UAV, the position determination and aircraft navigation system comprising:
a radio receiver to receive the ranging signals;
the positioning circuit, communicatively coupled to the radio receiver, that determines a range to each positioning radio using the received ranging signals, and computes a position of the UAV relative to the target point on the landing pad; and
a flight control system that determines a course for the UAV to a point centered above the target point of the landing pad at a predetermined altitude, flies the UAV to the point centered above the target point of the landing pad while maintaining the predetermined altitude, causes the UAV to descend vertically toward the target point when the UAV reaches the point centered above the target point of the landing pad at the predetermined altitude, and remains centered above the target point during vertical descent.