A flight jacket is a casual jacket that was originally created for pilots and eventually became part of popular culture and apparel. It has evolved into various styles and silhouettes, including the "letterman" jacket and the fashionable "bomber" jacket that is known today. The flight jacket Early history World War I In World War I, most airplanes did not have an enclosed cockpit, so pilots had to wear something that would keep them sufficiently warm. The U.S. Army officially established the Aviation Clothing Board in September 1917 and began distributing heavy-duty leather flight jackets; with high wraparound collars, zipper closures with wind flaps, snug cuffs and waists, and some fringed and lined with fur. World War II Leslie Irvin first designed and manufactured the classic sheepskin flying jacket. In 1926 he set up a manufacturing company in the United Kingdom, and became the main supplier of flying jackets to the Royal Air Force during most of World War II. However, the demand during the early years of the war was so great that the Irvin company engaged subcontractors, which explains the slight variations of design and colour that can be seen in early production Irvin flying jackets. As aerospace technology improved, the altitudes at which aircraft operated increased. Some heavy bombing raids in Europe during World War II took place from altitudes of at least , where ambient temperatures could reach as cold as −50 °C (−58 °F). The cabins of these aircraft were uninsulated, so a warm, thick flight jacket was an essential piece of equipment for every member of the crew. Flight jackets in the United States The two most historical American flight jackets are the A-2 jacket of the Air Force and the G-1 of the Naval Aviators. Although General “Hap” Arnold cancelled the original A-2 after twelve years because he wanted "something better", the A-2 remains the most recognizable and sought-after American flight jacket. The G-1, designed by the U.S. Navy to parallel the Air Corps’ A-2, lasted until 1978, when U.S. Congress cancelled it due to its tremendous popular appeal, which was overwhelming the Navy's supply system. Their popularity evolved into symbols of honor, adventure, and style. Hollywood films like Top Gun boosted sales of the G-1 tremendously, making bomber jackets collector and fashion items. In addition to the A-2 and G-1 jackets, shearling jackets, originally lined with fur, are recognized for being the warmest