Printed 'Naval Aircraft Flight Classification System' reference sheet (NAVAER-41-1A, Rev. 8-50), bound into a U.S. Navy pilot's personal flight log book covering October 1948 to January 1952. Naval aviators used this coding key to classify each flight's conditions, purpose, and type on official log entries — a system that took on added significance as pilots began logging combat, rescue, and transport sorties during the opening phase of the Korean War. Project: 218062