Abstract
The last forty years have seen a dramatic reduction in the environmental noise generated by civil aircraft; this reduction seems unlikely to continue for the current generation of aircraft. In the near term, replacing service aircraft with updated models may bring about significant benefits for those living near airports in western countries but have an adverse affect on other populations. Reductions in the noise levels generated by aircraft have been mainly due to advances in turbofan engine technology driven by increasingly restrictive regulation around airports. However, current estimates for increased passenger traffic in the coming decades and rising prices for aviation fuel may lead to vehicle designs with greater overall sound production. This article examines proposed future propulsion technologies and their possible impact on the noise environment. The implications of the introduction of new aircraft to the New Zealand airline fleets are also discussed.