A Servomechanism Approach to the Problem of Communication for Aircraft Control

The traffic-handling capability of a communication system used for aircraft control during airport traffic control, ground-controlled approach, and ground-controlled landing is studied. The system is treated as a multiloop servomechanism which includes both ground and airborne equipment. The factors which affect the location of the communications link in the system are discussed. These include message rate, airborne equipment or ground measurements necessary, flight geometry, and flight safety. It is shown that the minimum message rate is possible if the quantity transmitted is the same as the flight motion desired. Several methods are presented for increasing the traffic-handling capability by reducing the message rate. One of these introduces controlled blacklash into the outermost feedback loop and automatically determines the minimum message rate while navigating to a point. A dynamic analysis is used to determine the limitations of the method. The methods presented are illustrated by showing their application to automatic flight control during ground-controlled approach and ground-controlled landing.