MOAB — A preliminary government report does not pinpoint the cause of a May 30 plane crash that killed two men in Canyonlands National Park.

The National Transportation Safety Board report said the Cessna 172 crashed in remote, mountainous terrain about 32 miles south of Monticello. About two hours into the scenic flight, the pilot reported to another pilot that he was at the confluence of the Green and Colorado rivers. Nothing else was heard.

When the plane did not return to Canyonlands Airport, tour-company officials became concerned. A search led to the wreckage.

A hiker in the area saw the plane, which appeared to be below the rim of the canyon in a steep bank.

"The witness further stated that during both visual sightings of the airplane she failed to hear any engine noise," the NTSB report said.

As she was hiking back to the trailhead, she came upon the wreckage. The crash killed John W. Keys III, 66, of Moab, and Gary Kramer, 49, of Scottsdale, Ariz.