The Oklahoma Highway Patrol says a 43-year-old Midland, Texas man was killed when his ultralight aircraft crashed north of Spiro Friday evening.

Troopers identified the pilot as Richard Biggerstaff, Jr.

The OHP report says just before 7:45 p.m., a witness saw the aircraft make steep downward spiral into the ground.

According to KFSM, the CBS affiliate in Fort Smith, prior to the crash, the witness told the OHP he had watched the pilot take off and fly around the area for about 20 minutes.

The cause of the crash remains under investigation.