NTSB spokesman Terry Williams said the agency did a thorough investigation, looking at the “man, the environment and the machine” and was able to determine only that the pilot had lost control of the plane.
“Beyond that, we don't have anything else,'' he said.
Paul Branstetter, Olin and Paula Branstetter's son, said the NTSB's probable cause seemed “generic” and didn't answer many questions. Paul Branstetter, himself a pilot, said he took the findings to mean the agency wasn't able to find anything more specific.
“I don't think we'll ever have an answer,” he said.
Now more than a year after the crash, Paul Branstetter said the family has had a difficult time coping with the loss of both of his parents in a single incident.
“It's a struggle,” he said.
The accident came just two months shy of the anniversary of the Jan. 27, 2001, plane crash in Colorado that killed 10 people affiliated with the men's basketball program.
Branstetter, a former Oklahoma state senator, had flown coaches to trips before. At the time, OSU officials exercised limited oversight in cases where donors offered to fly university personnel for free. A travel policy was in place for student athletes, but coaches and athletic staff were allowed a great amount of leeway in making their own travel arrangements.
OSU officials amended that policy last November to place greater restrictions on travel. Among other changes, the new policy ended the practice of allowing coaches to exercise their own discretion when making travel arrangements that don't include student athletes.
The new policy also requires that a university aviation consultant approve all private aircraft that would be used for university business, as well as the pilots who would fly them.
OSU officials said they overhauled the policy as a result of the crash, but didn't tailor it to the specific facts of the accident. Officials wouldn't speculate as to whether last year's fatal flight would have taken off had the new policy been in force. However, both Branstetter and the plane would have had to receive approval from an aviation consultant before flying.