Most technological advances are accompanied by some degree of apprehension about their potentially catastrophic effect on safety and the environment. History provides countless examples. Notable in the field of transportation are the applications of the steam engine to the locomotive, the internal combustion engine to the horseless carriage, and the whole array of engines used in the flying machine. Immediate public safety is usually the primary concern, but pollution and noise are also cited as possible sources of long-term harm to the human species. Although the passage of time has seen some of these concerns justified, humanity has learned to live with them, whilst exploiting to the full the benefits of a wide variety of transportation modes. Indeed, in developed nations, the quality of life would be downgraded considerably without the benefit of fast, reliable and diverse modes of transport. As a result, the cost of environmental protection is considered a necessary burden.

Noise, as an environmental issue, has had a major impact on both the conceptual and detailed design of only one source of power in the field of transportation, arguably the one that has had great impact on international relationships, the modern aircraft engine. It was in the early 1960s, following the successful introduction of the jet engine into commercial airline service, that aircraft noise became an issue of substance. Hitherto, it had been regarded merely as an aggravation, and grievances were settled either privately, by the parties concerned, or in the civil courts. Interestingly, in the United Kingdom this latter facility was regarded as unnecessary, and Parliament virtually prevented U.K. citizens from having recourse to it as far back as 1920.