On 24 June 1947, businessman/pilot Kenneth Arnold of Boise, Idaho claims to see 9 objects flying “like a saucer would if you skipped it across the water” near Mount Rainer in the Cascade Mountains in Washington State.

As part of a survey by the Fortean Times in 2007 of various researchers of the ten cases from 1947 onwards that interested them the most, ufologist Peter Brookesmith indicated that this incident was one of two UFO cases with the “the greatest cultural effect”.

This incident came fourth in a survey in 1965 by Jacques Vallee of the opinion of various UFO groups as to the most significant UFO sightings. It also featured in a document (“the Rockefeller Briefing Document”) endorsed by Dr Mark Rodeghier (President of CUFOS), Richard Hall (Chairman of FUFOR) and Walter Andrus (President of MUFON) as containing “the best available evidence for the existence of UFOs”.

This incident is Case 1 in Isaac Koi's "Top 100" article,  since it was referred to in 359 of the books covered by that article.

This incident has also featured in lists by various UFO researchers of the top UFO cases, including the following:

• a list of Dennis Balthaser’s “ten favourite cases” in an article in the MUFON Journal in 2003.
• a list of twenty UFO cases produced by Bruce Maccabee in 1999 in response to a challenge to produce “the best evidence for an extraterrestrial origin for the UFO phenomenon”.
• a list by Don Berliner of “the top 10 cases of World Ufology” in an interview made available on the UFO UpDates discussion List on 14 January 2007.