M. Fisher. Ryan, also the inventor of the retractable safety seat belt now required in automobiles, began working on the idea of a flight recorder in 1946, and invented the device in response to a 1948 request from the Civil Aeronautics Board aimed at establishing operating procedures to reduce air mishaps. The requirement was for a means of accumulating flight data. The original device was known as the "General Mills Flight Recorder". The benefits of the flight recorder and the coding apparatus for flight recorders were outlined by Ryan in his study entitled "Economies in Airline Operation with Flight Recorders" which was entered into the Congressional Record in 1956. Ryan's flight recorder maintained a continuing recording of aircraft flight data such as engine exhaust temperature, fuel flow, aircraft velocity, altitude, control surfaces positions, and rate of descent. A "Cockpit Sound Recorder" (CSR) was independently invented and patented by Edmund A. Boniface Jr., an aeronautical engineer at Lockheed Aircraft Corporation. He originally filed with the US Patent Office on February 2, 1961, as an "Aircraft Cockpit Sound Recorder". The 1961 invention was viewed by some as an "invasion of privacy". Subsequently Boniface filed again on February 4, 1963, for a "Cockpit Sound Recorder" (US Patent 3,327,067) with the addition of a spring-loaded switch which allowed the pilot to erase the audio/sound tape recording at the conclusion of a safe flight and landing. Boniface's participation in aircraft crash investigations in the 1940s and in the accident investigations of the loss of one of the wings at cruise altitude on each of two Lockheed Electra turboprop powered aircraft (Flight 542 operated by Braniff Airlines in 1959 and Flight 710 operated by Northwest Orient Airlines in 1961) led to his wondering what the pilots may have said just prior to the wing loss and during the descent as well as the type and nature of any sounds or explosions that may have preceded or occurred during the wing loss. His patent was for a device for recording audio of pilot remarks and engine or other sounds to be "contained with the in-flight recorder within a sealed container that is shock mounted, fireproofed and made watertight" and "sealed in such a manner as to be capable of withstanding extreme temperatures during a crash fire". The CSR was an analog device which provided a continuous erasing/recording loop (lasting 30 or more minutes) of all sounds (explosion,