This system effectively gave range and height data bases which could be added to autopilot heading info and so enriched the control functions enabling automatic landing opportunities. Research during the first few years at BLEU led to the conclusion that a promising approach to blind landing would be a fully automatic system, and to the definition of the requirements for such a system, later designated "Autoland". The Instrument Landing System (ILS) was developed from wartime technology. ILS projected two perpendicular beams that aircraft could use to align themselves with the runway on final approach. Although ILS successfully guided pilots toward the airport, it was not accurate enough to provide guidance during landing. BLEU's first attempt at solving the problem was to place a cable, one mile long, extending from each end of the runway for a length of one mile, similar to the Ambrose Channel pilot cable. The cable worked with an improved FM radio altimeter that BLEU developed, capable of resolving height differences to 2 feet at low altitude. The team safely conducted thousands of test landings using this system. BLEU realized that most airports did not have room to place one-mile cables, so they continued working on a radio-driven solution. In collaboration with Smiths Industries Ltd., BLEU also developed coupling units to derive the commands to the autopilot from the guidance signals, and auto-throttle. Components of the system were developed separately on several types of aircraft, including the Lancaster, Viking, Devon and the Albemarle. A demonstration of the techniques used was given to military and government representatives in May 1949. By 1950 the entire system had been installed on a DH Devon and the first demonstration of Autoland was given on that aircraft on 3 July 1950. Over the next 20 years, BLEU in conjunction with UK industry and the UK airworthiness authority, was responsible for almost all of the pioneering work needed to convert the concept of those experimental demonstrations into safe, accurate blind landings by large transport aircraft. The system in use during the early 2000s is basically the same as that used experimentally in 1950. The following diagram, from J S Shayler's 1958 memorandum, shows how the different components of the system, and guidance signals, were used during the consecutive phases of an automatic landing. During the early 1950s, as a preliminary to the development of the full Autoland system, automatic approach trials were carried out on Valetta, Meteor and Canberra aircraft. The Canberra, "VN799", was acquired in 1953 but was a write-off following a crash landing in August that year due to a double engine failure, fortunately without serious injury to the crew.