entitled "A Device for Assisting Investigation into Aircraft Accidents". Warren built a prototype FDR called "The ARL Flight Memory Unit" in 1956, and in 1958 he built the first combined FDR/CVR prototype. It was designed with civilian aircraft in mind, explicitly for post-crash examination purposes. Aviation authorities from around the world were largely uninterested at first, but this changed in 1958 when Sir Robert Hardingham, the secretary of the British Air Registration Board, visited the ARL and was introduced to David Warren. Hardingham realized the significance of the invention and arranged for Warren to demonstrate the prototype in the UK. The ARL assigned an engineering team to help Warren develop the prototype to airborne stage. The team, consisting of electronics engineers Lane Sear, Wally Boswell and Ken Fraser, developed a working design that incorporated a fire-resistant and shockproof case, a reliable system for encoding and recording aircraft instrument readings and voice on one wire, and a ground-based decoding device. The ARL system, made by the British firm of S. Davall & Sons Ltd, in Middlesex, was named the "Red Egg" because of its shape and bright red color. The units were redesigned in 1965 and relocated at the rear of aircraft to increase the probability of successful data retrieval after a crash. Carriage of data recording equipment became mandatory in UK-registered aircraft in two phases, the first for new turbine-engined public transport category aircraft over in weight was mandated in 1965, with a further requirement in 1966 for piston-engined transports over , with the earlier requirement further extended to all jet transports. One of the first UK uses of the data recovered from an aircraft accident was that recovered from the Royston "Midas" data recorder that was onboard the British Midland Argonaut involved in the Stockport Air Disaster in 1967. US designs The flight recorder was invented and patented in the United States by Professor James J. "Crash" Ryan, a professor of mechanical engineering at the University of Minnesota from 1931 to 1963. Ryan's "Flight Recorder" patent was filed in August 1953 and approved on November 8, 1960, as US Patent 2,959,459. A second patent by Ryan for a "Coding Apparatus For Flight Recorders and the Like" is US Patent 3,075,192 dated January 22, 1963. An early prototype of the Ryan Flight Data Recorder is described in the January 2013 Aviation History article "Father of the Black Box" by Scott