Arnold had taken off from Chehalis, Washington, intending to fly to Yakima, Washington. About 3:00P.M. he arrived in the vicinity of Mount Rainier. There was a Marine Corps C-46 transport plane lost in the Mount Rainier area, so Arnold decided to fly around awhile and look for it. He was looking down at the ground when suddenly he noticed a series of bright flashes off to his left. He looked for the source of the flashes and saw a string of nine very bright disk- shaped objects, which he estimated to be 45 to 50 feet in length. They were traveling from north to south across the nose of his airplane. They were flying in a reversed echelon (i.e., lead object high with the rest stepped down), and as they flew along they weaved in and out between the mountain peaks, once passing behind one of the peaks. Each individual object had a skipping motion described by Arnold as a "saucer skipping across water." During the time that the objects were in sight, Arnold had clocked their speed. He had marked his position and their position on the map and again noted the time. When he landed he sketched in the flight path that the objects had flown and computed their speed, almost 1,700 miles per hour. He estimated that they had been 20 to 25 miles away and had traveled 47 miles in 102 seconds. I found that there was a lot of speculation on this report. Two factions at ATIC had joined up behind two lines of reasoning. One side said that Arnold had seen plain, everyday jet airplanes flying in formation. This side's argument was based on the physical limitations of the human eye, visual acuity, the eye's ability to see a small, distant object. Tests, they showed, had proved that a person with normal vision can't "see" an object that subtends an angle of less than 0.2 second of arc. For example, a basketball can't be seen at a distance of several miles but if you move the basketball closer and closer, at some point you will be able to see it. At this point the angle between the top and bottom of the ball and your eye will be about 0.2 of a second of arc. This was applied to Arnold's sighting. The "Arnold-saw-airplanes" faction maintained that since Arnold said that the objects were 45 to 50 feet long they would have had to be much closer than he had estimated or he couldn't even have seen them at all. Since they were much closer than he estimated, Arnold's timed speed was all wrong and instead of going 1,700 miles per hour the objects were traveling at a speed closer to 400 miles per hour, the speed of a jet. There was no reason to believe they weren't jets. The jets appeared to have a skipping motion because Arnold had looked at them through layers of warm and cold air, like heat waves coming from a hot pavement that cause an object to shimmer. The other side didn't buy this idea at all. They based their argument on the fact that Arnold knew where the objects were when he timed them.