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Washington, at which time the pilot altered his heading and took a direct course to Dayton. At about 3:15 p.m., this flight passed some twenty miles south of the scene of the accident and the pilot stated that he maintained contact with the exception of a short period of instrument flying, during which there was a very heavy downpour of rain, slight turbulence, and no lightning.
III.
ANALYSIS OF FACTS — DISCUSSION OF POSSIBLE CAUSES
In the preceding section of this report we have set out a summary of the evidence disclosed by the investigation. From the facts previously discussed, it appears that the flight of Trip 19 proceeded normally until 2:31 p.m. when it reached the Herndon fan-marker at 4000 feet, climbing. We also know that the crash occurred approximately 25 miles northwest of the Herndon fan-marker about ten minutes later. In searching for the probable cause of this accident, it is necessary to analyze all of the facts in an effort to discover what event or combination of events occurred during that ten-minute interval which resulted in the crash of the airplane.
In seeking to determine the course of events that led to this accident, in the absence of any direct testimony from any actual observer on board the aircraft and in view of the circumstantial evidence of record, we are obliged to look for the extraordinary, and to examine into the possibility and probability of occurrences that are so rare in practical operating experience as to be highly obscure, if not virtually unknown. Nothing within the ordinary range of experience, and no combination of events of which the occurrence could be regarded at all likely, would have sufficed to produce this
