Overview

Though long of concern to neighbors of major airports, aircraft noise first became a major problem with the introduction of turbojet-powered commercial aircraft (Boeing 707, Dehavilland Comet) in the late 1950s. These aircraft were powered by turbojet engines originally developed for military aircraft. It was recognized at the time that the noise levels produced by military aircraft would be unacceptable to persons living under the takeoff pattern of major airports such as New York's Kennedy (then Idlewild) and London's Heathrow. Accordingly, much effort was devoted to developing jet noise suppressors (reference ^[9.1]), with some modest success. Takeoff noise restrictions were imposed by some airport managements, notably the Port of New York Authority, and nearly all first-generation turbojet-powered transports were equipped with jet noise suppressors at a significant cost in weight, thrust, and fuel consumption.

The introduction of the turbofan engine (Rolls-Royce Conway, Pratt & Whitney JT3-D), with its lower jet velocity, temporarily alleviated the jet noise problem but increased the high-frequency turbomachinery noise, which became a severe problem on landing approach as well as on takeoff. This noise was reduced somewhat by choosing proper rotor and stator blade numbers and spacing and by using engines of the single-mixed-jet type.

In spite of these efforts, the increasing volume of air traffic resulted in unacceptable noise exposures near major urban airfields in the late 1960s, leading to great public pressure for noise control. This pressure, and advancing technology, led to Federal Aviation Rule Part 36 (FAR-36), which became effective on...