Pacific Northwest Wave June 1947

On June 24, 1947, private pilot Kenneth Arnold was flying his CallAir A-2 near Mount Rainier when he observed nine crescent or heel-shaped objects flying in a chain formation at an estimated speed of 1,700 mph — faster than any aircraft of the era. Arnold's description of their motion as being 'like saucers skipping on water' gave birth to the term 'flying saucers.' Arnold's report to the FBI's Tacoma field office was one of over 20 independent UAP reports filed across the Pacific Northwest on the same day — a fact rarely mentioned in popular accounts of the case. The Arnold sighting triggered the modern UAP era, producing a cascade of hundreds of thousands of reports globally within weeks. FBI Director Hoover's response — ordering field offices to collect all disc sighting reports — established the Bureau's UAP documentation role. The Army Air Forces immediately investigated and classified their findings. General Nathan Twining's September 1947 memo stating that flying discs were 'real and not visionary' was a direct response to the Arnold case and the wave it triggered.