Causes of Fatal Nebraska WWII Air Crashes
Causes of Crash
Nebraska's 56 Fatal WWII Crashes
Pilot Error = 32
Mechanical = 12
Unknown = 8
Weather = 3
Structural = 1
This list does not include the four accidents where airmen were killed, but there was no crash of the plane.
Pilot error includes everything from poor judgment to mid-air collisions.   All planes involved in a mid-air collisions are placed in this category even though it was usually the error of only one pilot involved.
Mechanical includes engine failure, fire, or any other item that the pilot might have otherwise been able to handle.   The pilot did not show poor judgment in those aircraft placed under this category.
Structural includes part of the plane either coming off or not operating properly that directly contributed to the crash. This does not include engine failure.
Unknown is a result of there being no eyewitnesses or survivors to help determine the cause of the crash.   Those investigating the crash could not determine what happened.
Weather involves a situation where the pilot had the plane under control, but circumstances with the weather such as lightning or high winds was the direct cause of the crash.
The above list is not necessarily the "official" military cause of crash since some research has indicated otherwise, and all things taken into consideration it could be viewed differently.   In most cases the list does reflect what was stated in the "Aviation Accident Report" as the cause of crash.