Continuous Descent Approaches - Validation in Simulation and Flight Trials

The application of Continuous Descent Approaches (CDA) is an innovative method to reduce the noise that can be heard on the ground of airplanes during their landing approach. The CDA’s main characteristic is a continuous descent from an altitude at which the airplane is inaudible on the ground to the touchdown on the runway. The point at which this descent is commenced has to be determined in advance for each approach. The Institute of Flight Guidance of the German Aerospace Centre (DLR) has developed an Advanced Flight Management System (AFMS) that is able to calculate CDAs and also to guide the airplane along the approach. The calculations are based on BADA-files (Base of Aircraft Data) provided by Eurocontrol, enabling the AFMS to determine CDAs for almost any transport airplane types. This paper describes after a general explanation of CDAs and the AFMS how the AFMS’ CDA calculations and guidance function have been validated during flight trials and tests in a full flight simulator on different airplane types. Generally, the airplane has stayed within 150 feet of the predetermined flight path and three seconds around the pre-dicted time of arrival in simulator tests and 10 seconds in real world flight trials.