Flyover-Noise Reduction of Commercial Aircraft via Reduced Slat Deflections and Modified Flight Procedures

Current regulation and operation of commercial aircraft result in flyover noise that generates public protest from residents well outside the recognized noise footprint of modern airports. This noise issue was recently exacerbated by the implementation of NextGen air-traffic control which uses GPS-navigation for predictable flight paths and improved efficiency. A side-effect of the narrow flight corridors is a perceived increase in noise level and annoyance experienced by the residents directly under the flight paths. As a possible solution to the community noise issue, the feasibility of a lower slat deflections and modified flight procedures were explored. To document the maximum potential noise reduction, field measurements were conducted on the ground at locations before and after slat deployment. For safety considerations, the stall margin of a lower slat deflection was computed for a realistic geometry based on a modern commercial aircraft. The logistics of setting lower slat angles on current aircraft were also investigated through discussions with the FAA (Federal Aviation Administration) and aircraft manufacturers. The results suggest that community flyover noise could be reduced via lower slat deflections during early approach, but that modifying current aircraft would be difficult due to existing control systems and hurdles in certification. Alternatively, modifications to existing flight procedures could reduce the perceived noise of the NextGen flight patterns. For next generation commercial aircraft, reduced slat deflections could be considered if mandated by FAA noise requirements during early approach.