Fujita's best-known contributions were in tornado research; he was often called "Mr. Tornado" by his associates and by the media. In addition to developing the Fujita scale, Fujita was a pioneer in the development of tornado overflight and damage survey techniques, which he used to study and map the paths of the two tornadoes that hit Lubbock, Texas on May 11, 1970. He established the value of photometric analysis of tornado pictures and films to establish wind speeds at various heights at the surface of tornado vortices. Fujita was also the first to widely study the meteorological phenomenon of the downburst, which can pose serious danger to aircraft. As a result of his work, in particular on Project NIMROD, pilot training worldwide routinely uses techniques he pioneered to provide instruction to students.