It may be some time before the military is ready to release a cause for yesterdays fighter jet crash in Knox County. A Missouri Air National Guard plane went down south of Vincennes Wednesday morning. The pilot ejected safely before the F-15 smashed into a corn field. The military safety board says the plane was almost 30 years old, but they dont believe the age of the aircraft was to blame for the crash. Air National Guard officials praised the pilot for keeping the plane away from populated areas before the crash.