Factors Affecting Measured Aircraft Sound Levels in the Vicinity of Start-of-Takeoff Roll

This paper presents the findings of a recently conducted measurement and analysis program of jet transport aircraft sound levels in the vicinity of a start-of-takeoff roll. The purpose of the program was two-fold: (1) to evaluate the computational accuracy of the Federal Aviation Administration's Integrated Noise Model (INM) in the vicinity of start-of-takeoff roll with a recently updated database (INM 3.10) and (2) to provide guidance for future model improvements. Focusing on the second of these two goals, this paper examines several factors affecting Sound Exposure Levels (SELS) in the semicircular area behind the aircraft brake release point at the start-of-takeoff roll. In addition to the aircraft type itself, these factors included (1) the geometric relationship of the measurement site to the runway, the wind velocity (speed and direction), aircraft gross weight, and start-of-roll mode (static or rolling start).