Critical Conditions for the Automatic Control of Landing from Decision Height in Variable Winds

摘要

The critical conditions at decision height that could cause unsafe landing situations were investigated. The analysis of these conditions was performed using a method of automatic control which employs the reference state vector and the reference control vector. A landing tunnel approach was developed using airspeed and altitude as the basic variables with corrections for sink rate and allowance for the presence of wind shear. The landing tunnel concept consists of a landing window that varies with altitude allowing for the possibility of a go-around decision at any moment during the landing maneuver. A procedure for performing the go-around maneuver using a safe minimum height or, if necessary, maximum aircraft capability, was developed which always allows the maximum possible clearance of the ground. An outline of an autoland system incorporating the procedure developed is presented based on an on-board microprocessor to produce the necessary computations.