The United States Air Force has produced a surprising number of iterations of Service and Dress uniforms over the seven-plus decades it has been an independent branch of the Armed Forces of the United States, but the wear of 1 1/2-inch silver braid was authorized for only one of them: the Informal White uniform introduced sometime in the early 1960s.
Featuring the same design as the U.S. Air Force Blue Service Dress uniform, the wear guidance for the Informal White uniform originally called for silver (aluminum) braid on the coat sleeves and trouser legs; General Officers wore 3/4-inch silver sleeve braids and all other Officers wore 1/2-inch braid. According to the Web site USAF Flag Ranks, this configuration of the Informal White uniform soon became required for certain duty positions, including (but not limited to) Air Attachés and Assistants (at the direction of the Air Force Chief of Staff) and all General Officers assigned for duty in the National Capital Region.
In the mid 1970s, the 3/4-inch silver sleeve braid for General Officers was replaced by 1 1/2-inch braid, a change that was apparently temporarily rescinded then reintroduced in the 1980s. It marked the only instance where silver braid of this width was used on an Air Force uniform; today, 1 1/2-inch blue braid is worn by General Officers wearing the Men’s or Women’s Service Dress uniform.