Incident No. 58 — 4 August 1947, Sunset, near Bethel, Alaska.
A pilot and his co-pilot observed a black object of the design and approximate dimensions of a C-54 fuselage, flying at 500-1000 ft altitude N.W. The object crossed their path at right angle, and they pulled up to 1200 ft to avoid a collision, then chased it at 170, but lost sight of it in four minutes. They estimated the speed of the object to be three times their own, or 510 MPH. Assuming the estimate of speed to be correct, elementary computations determine the distances object traveled as 34 miles in four minutes while the observer's airplane moved eleven miles in the same period. Therefore, the object was more than twenty miles distant when last seen. To be capable of being seen at this distance under the conditions given, the object would have to be about 50 feet in its smallest or end-on dimension. If this were true, and the object was proportionate with a C-54 fuselage, its length would be about 500 ft. Assuming the estimate of speed to be incorrect, but time in sight to be correct, the problem is figured in reverse, using as a reasonable width 15 feet. In this event the object would have been less than ten miles away when lost to sight, therefore, it would have traveled about eighteen miles in four minutes, giving a speed of less than 300 MPH.
AIC Opinion: It is believed that the pilots were suddenly startled by a conventional aircraft crossing their path, and that as they gave chase to the aircraft which was "silhouetted against a brilliant evening sky", they were partially blinded, and were therefore unable to discern wings or engines.