Kenneth Arnold
Before the sighting
Boise businessman + experienced general-aviation pilot. Founded Great Western Fire Control Supply 1940.
During the sighting
Jun 24 1947 flying Boise → Chehalis → Yakima → Pendleton; on diversion to search for downed Marine C-46 (with $5,000 reward). Near Mount Rainier reported 9 shiny objects in echelon formation, 8 disc/pie-pan and 1 distinctly crescent. Speed estimate >1,700 mph (he low-balled to 1,200). Described motion 'like a saucer if you skip it across water' AND shape 'flat like a pie-pan, convex, half moon' — reporters AP-wired 'flying saucers' from BOTH the motion AND shape language.
After the sighting
Claimed ~7 further personal sightings. Theory drifted: 1950 ET → 1952 first 'space animal' hints → 1955 explicit 'sky jellyfish' → 1962 full atmospheric-living-organisms hypothesis. Co-authored 'The Coming of the Saucers' (1952) with Ray Palmer (Amazing Stories editor, Fate co-founder). $200 Palmer retainer to investigate Maury Island (now widely a hoax). 1962 Idaho Lt Gov run (lost).
Research notes
Trained, high-time pilot with SAR experience, sober daytime sighting, contemporaneous report. Strong baseline. Downgraded by self-derived speed math, Palmer/Maury-Island commercial entanglement, drift to 'space animals', Ruppelt-noted detail inconsistencies. Mundane explanations (mirage, pelicans, meteor train) cover much but none cleanly explains all. The story that defined the modern UFO era.