Development of Noise Abatement Approach Procedures

Abstract

*This article describes initial results of an Airbus research project, aimed at the development of efficient operational noise abatement approach procedures that can be operated with in-service aircraft, either manually or in FMS managed mode. The project is focused on the Continuous Descent Approach (CDA) procedure, defined as an approach procedure without recourse to level segments below a height of typically 7000ft. After a first qualitative review, a noise and performance analysis has been performed for a number of CDA variants for Airbus A320 and A340 aircraft. The FMS approach procedure, including a level-off deceleration segment prior to glide slope intercept, was selected as baseline procedure. This procedure provides optimized performance and noise relief relative to conventional approach procedures. The first CDA analysis revealed a maximum descent angle, allowing convenient deceleration in clean configuration, of 2° and modest associated noise reduction relative to the baseline procedure. An optimized version of this CDA procedure, featuring a modified configuration change schedule, led to 5dBA noise relief relative to the baseline procedure. On an experimental basis, also CDA procedures with steep final glide slope angles were evaluated. Following these assessments, a series of A340 flight simulator tests was undertaken to evaluate in-flight characteristics and pilot perception for the selected CDA procedures. Simulations executed in manual mode enabled identification of acceptable descent flight path angles. Simulations of the same procedures in FMS managed mode provided further insight in operational feasibility and pilot workload issues.