The introduction of the Mark 10 Decca promised certain advantages over existing types and it was therefore deemed expedient to examine the potentialities of the equipment, its operational accuracy and general suitability for airline operation. The Ministry of Transport and Civil Aviation in conjunction with British European Airways were subsequently involved in two series of tests which began in early 1957 and continued into 1958. These tests were designed to determine the operational suitability of the Mark 10 Decca receiver and, in addition, provide a direct comparison between the performance of Mark 10 and Mark 7 equipment. All the flights were made, by day and night, on B.E.A. routes within the cover of the English chain. Ample opportunity was afforded to study the equipment under typical service conditions.