Perry Inhofe reported a control problem with his airplane shortly before crashing in Owasso earlier this month, according to the National Transportation Safety Board.
The NTSB has released its Preliminary Report on the crash.
According to the report, Inhofe's twin-engine Mitsubishi MU-2B-25 crashed at about 3:46 p.m. on the west side of Owasso on November 10, 2013 while attempting to land at Tulsa International Airport.
The NTSB says a ground controller cleared the plane to land on runway 18L, which means it was landing to the south on the main runway. The controller also instructed the pilot to reduce his speed to 150 knots.
The NTSB says Inhofe acknowledged both instructions, but then his plane started to make a left turn. When the controller asked Inhofe about the unexpected turn, Inhofe radioed that he had a control problem.
When the controller saw that the turn was continuing, he cleared Inhofe to maneuver to the west and asked if the pilot needed assistance. The pilot told the controller his left engine was shut down.
The controller declared an emergency for the pilot and asked how many people were on board and how much fuel the plane had. The controller received no further communications from the pilot.
The NTSB says radar indicates the plane made a 360-degree left turn about five miles from the north end of runway 18L and then contact was lost.
Witnesses told investigators they saw the aircraft making the turn with its landing gear extended and the propeller on the left engine not turning. They reported seeing the plane make a right turn, then a left turn and then a steep spiral to the left as it disappeared from view.
The NTSB says the plane's landing gear was extended when investigators got to the crash scene. They also noted that the propeller on the left engine was in the feathered position, which means its blades were turned parallel to the direction of flight to minimize wind resistance, which was consistent with the engine having been shut down.
Images from Osage SkyNews 6 also confirm that the propeller was feathered.
Perry Inhofe, the son of U.S. Senator Jim Inhofe, was a well-known orthopedic surgeon in Tulsa. People who knew him say he was also a loving father, husband, son and friend.
He was a very experienced commercial and instructor pilot.
Records show he bought the plane in September. The FAA requires pilots to get additional training for this plane because of its safety record. Inhofe completed that training a few days before the crash.
The NTSB's Preliminary Report is the first of three reports it will release on the crash. Next up will be the Factual Report followed by the Probable Cause Report. It usually takes the NTSB many months, sometimes years, to complete all three reports on a single fatal crash.