Kenneth Arnold sighting, Mount Rainier, Washington

Kenneth Arnold, a Boise, Idaho businessman and private pilot, reported on 24 June 1947 that he saw nine objects near Mount Rainier, Washington. A Fourth Air Force checklist recorded the time as 1500, the distance as 20 to 25 miles, the time in sight as 2-1/2 to 3 minutes, and the speed as approximately 150 MPH (checklist). Arnold's own written account said he clocked the chain between Mt. Rainier and Mt. Adams in one minute and forty-two seconds (Arnold statement). Press reports of the same week gave 1,200 miles an hour (Washington Times-Herald).

Arnold was interviewed on 12 July 1947 by Special Agent Frank M. Brown of the Fourth Air Force Counter Intelligence Corps. Brown wrote that he believed Arnold saw what he stated, and that an aeronautical map showed the distances, speed, course and size could very possibly be facts (CIC memo). The Fourth Air Force synopsis listed Arnold's report as the first of the disc reports in its area (Fourth Air Force report). The Air Force chronology and a 1955 Blue Book study both described the sighting as the start of public interest in the subject (chronology; Special Report 14).

Several mundane explanations appear in the file. Press accounts recorded early suggestions of reflections, persistent vision and snow blindness (Milwaukee Sentinel). Arnold rejected the mirage idea, saying he had opened his window and viewed the objects unobstructed (Arnold statement). A magazine article in the file argued that Arnold may have been flying near a layer of inversion haze (article). Captain Ruppelt's 1952 briefing said misinterpretation of conventional objects could possibly account for all reports, and attributed part of the early peak to mass hysteria (Ruppelt transcript).

Later events drew in Arnold. A 27 August 1947 FBI memo recorded that he travelled to Tacoma on 30 July at the request of editor Raymond Palmer to look into disc fragments reported by Fred Crisman and Harold Dahl (FBI memo). A teletype said the Dahl and Crisman story was possibly started to promote the sale of slag, though this was not verified (teletype). A prospector, F. M. Johnson, wrote on 20 August that he had seen the same objects from the Mt. Adams district (letter).