The recording of aircraft operational data in service has long been considered to be a desirable addition to the data available to an airline. A limited amount of this information has always been provided by the pilot's log, but the capability of recording this data automatically has been delayed until recent years by the lack of recording systems which were both reliable and yet not too costly to the airline's overheads. The availability of possible systems in the immediate post-war years led to attempts to introduce governmental regulations covering the provision of such systems, but it was not until 1958 that the design of reliable airborne systems led to the introduction by the CAB of the first American regulations for this type of equipment. These American regulations were followed by other countries, notably France, Australia and the UK. The mandatory use of aircraft flight recorders derived from government requirements to record a limited number of flight parameters to assist in the evaluation of aircraft accidents.