The causes of two deadly plane crashes on opposite ends of the state remain a mystery as the National Transportation Safety Board continues its investigations.

In a recently released preliminary report on an Aug. 8 crash that killed three men near Monticello, the NTSB does not pinpoint a cause. A number of witnesses saw the plane, but none saw the crash that killed Eric Johnson, Brian Bayles and Kim Acton as they flew over the Four Corners area spotting wildlife.

"Two witnesses reported that the airplane's engine sounded steady with no changes in sound," the NTSB report said. "A witness traveling north on a nearby highway adjacent to the accident site reported that he observed an airplane circling in the vicinity with the wings 'completely up and down' before the airplane's wings leveled onto a westerly heading. The witness added that the airplane was at an 'extremely low altitude' before he lost sight of the airplane below the horizon."

The Piper single-engine plane crashed into a field, leaving a debris path 190 feet long. A final report could be issued within the next year.

The day after that crash, two people died when a Cessna crashed onto a beach near Garden City, near Bear Lake.

The NTSB report said the pilot, Charles Wesley McCall, of Kent, Wash., flew near a witness's cabin to signal his friend that he would be landing. Flying approximately 500 feet above the beach, the witness said the plane made a pass and circled a couple of times. Another witness said the plane was doing turns and banks in excess of 45 degrees.

"Then the pilot started flying north over the water along the beach, the nose of the airplane suddenly pitched up, the left wing dipped and the nose swung around like a hammerhead," the report said. "The airplane then ... went into a nose-dive straight into the ground."'

The crash killed McCall and Deborah Lucero, both of Washington state. The wreckage was recovered for further examination, the NTSB said.

On Friday, 10 people from Cedar City were killed in a plane crash from Moab. The cause of that crash remains under investigation.

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