"INTRODUCTION This Item presents a background to the handling qualities of aircraft@ examining those factors that play a role in the ease and safety with which a pilot flies an aircraft. Such factors encompass the stability and response characteristics of the aircraft@ the operation of the aerodynamic control surfaces and the engine thrust levels which enable the pilot to: (i) trim an aircraft@ (ii) maintain control during continuous disturbances and (iii) manoeuvre an aircraft. It is implicitly assumed that when a pilot exercises control of an aircraft the mental and physical workload entailed is comfortably within his capabilities. A distinction is made in this Item between ""handling qualities"" and ""flying qualities""@ terms that are often used interchangeably elsewhere. The former term is used to describe those parameters that characterise the stability@ control and response of an aircraft and so govern the ease and precision with which a pilot is able to fly an aircraft. Flying qualities@ in contrast@ relate to the pilot assessments of how well he is able to fly an aircraft to complete the range of tasks required and are wholly subjective in character. Two other terms are meaningful in the context of the present topic. The first is ""handling quality criteria"" which relate to the identification and quantification of those parameters that characterise the handling qualities. The second term is the ""flying quality requirements"" which are the statutory regulations to which all aircraft must conform in order to be certificated to fly and are laid down by the government bodies responsible for aviation in the various countries. For civil aviation in the UK@ Requirements are issued by the Civil Aviation Authority (CAA) and consist of various documents published either as Joint Airworthiness Requirements (JAR) jointly agreed upon by a number of European countries@ or as British Civil Airworthiness Requirements (BCAR). In the USA the regulation authority is the Federal Aviation Agency (FAA). The requirements@ both in the UK and USA@ usually consider light aeroplanes (lt;5700 kg) and large aeroplanes (gt;5700 kg) separately. The military specification in the UK is the ""Design and Airworthiness Requirements for Service Aircraft""@ Def. Stan. 00-970 published by the Ministry of Defence. These correspond wherever possible with the USA ""Military Specification@ Flying Qualities of Piloted Airplanes""@ MIL-F-8785C@ published in 1980 which was superseded in 1987 by Military Standard MIL-STD-1797. The nature of both the civil and military requirements is qualitative@ expressing the conditions for safe flight throughout the designated flight envelope. However@ in the military field@ a great deal of research combined with flight experience of experimental@ prototype and production aircraft has been carried out in many countries for many years. The results of these studies have been incorporated in the specifications for aircraft flying qualities and provide fairly comprehensive quantitative information in terms of the handling quality criteria for acceptable means of compliance with the requirements. The military requirements can encompass civil aircraft operation as well as military."