The essentials in 30 seconds
Le June 24, 1947, the private pilot Kenneth Arnold was flying over the Cascades near Mount Rainier (Washington State) when he saw nine shiny objects flying in formation at a speed he estimated at more than 1,900 km/h — impossible for the time. Describing their movement to the press as that of "a saucer ricocheting on water", he sees a journalist transform his comparison into “flying saucers” — flying saucers. The term travels around the world in 48 hours. Two weeks later, Roswell. The modern era of UFOs begins here.
What Arnold Describes — and What He Never Said
Founding irony: Arnold never said that objects had the shape saucers — he described their movement. The objects were according to him flat, crescent-shaped for one of them. But the word "saucer" imprinted itself on the world's imagination, and thousands of witnesses then reported... saucers. It's one of the most documented examples of how a word shapes a social phenomenon — a lesson every reader of UAP files should keep in mind.
A serious witness, an official file
Arnold was an experienced pilot, respected businessman, and firefighting equipment salesman flying daily into the mountains. Air Force investigates; his case opens the file that will lead to Project Sign then Blue Book. The proposed explanations – mirages, geese, prototypes – have never achieved consensus. The case remains officially unexplained, and its influence is an absolute historical fact: each file of the PURSUE database of 2026 descends in a direct line from this flight of June 24, 1947.
The minute-by-minute story
Around 3 p.m., Arnold took off from Chehalis for Yakima aboard his CallAir A-2. He takes a detour: a C-46 military transport plane has crashed on the slope of Mount Rainier, and there is a $5,000 reward for locating it. It was while searching for this wreck, at around 2,800 meters above sea level, that a luminous burst struck his eye – like a mirror in the sun. Then eight more. The objects line up the Cascade ridge from Mount Rainier toward Mount Adams. Arnold, methodical, times them between the two summits: 1 minute 42 seconds for approximately 80 kilometers. The calculation gives more than 2,700 km/h - he will conservatively retain 1,900. No aircraft from 1947 approaches these speeds.
The shock wave: summer 1947
On June 25, Arnold reported his sighting to Pendleton's journal. On the 26th, the phrase “flying saucers” was on tickers across the country. In the six weeks that followed, the American press listed more than 800 reports — including, on July 8, the affair of Roswell. The overwhelmed Air Force launched Project Sign in January 1948 - the 1948 report of which appears today in the 4th tranche PURSUE (exhibit DOW-UAP-D097). The circle has come full circle: the file opened by Arnold in 1947 is the same one that the Pentagon reopens in 2026.
Frequently asked questions
Did Kenneth Arnold see “saucers”?
No — he described the movement of objects (“like a saucer ricocheting on water”), not their shape. He was talking about flat objects, one crescent-shaped. The word “saucer” is a journalistic creation.
Has the case been explained?
No. Mirages, geese, secret prototypes: no hypothesis has reached consensus. Arnold, an experienced pilot and a credible witness, maintained his story throughout his life.
Why is this case seminal?
He triggered the first global wave of reports, invented the vocabulary of the phenomenon and provoked the creation of the first official American investigations (Sign, then Blue Book).
Sources
- Period press archives · official reports and documents cited in the article · corrections policy.