H-Dot Automatic Carrier Landing System for Approach Control in Turbulence

The Automatic Carrier Landing System (ACLS) provides a fully automatic approach and landing capability for high-performance carrier-based fighter aircraft. Approach path air turbulence produces significant touchdown error. Using power spectral density definitions of turbulence, a method to determine flight-path deviation due to turbulence and effects of changing system control laws to reduce dispersions and improve ACLS performance is presented. This technique, as applied to an F-4J ACLS fleet configuration, results in significant improvement using a vertical rate (H-Dot) reference in the autopilot control law. The F-4J H-Dot avionics mechanization was implemented and flight test results are discussed.