In preparing this lecture I was conscious of the fact that there were many phases of the development of a modern fighter which I had not covered, and which would possibly be of greater interest to the specialists on that particular subject than those that I did include. To them I offer my apologies, however, this lecture is not intended to be a handbook or reference on the design of all-weather fighter aircraft, but was prepared more or less as a chronicle of the main events leading up to the current development flying of Canada's newest defence weapon system, the supersonic all-weather CF-105, or Avro Arrow, and its associated equipment and environment (Fig. 1).