BOZEMAN (AP) — Federal investigators say an airplane that crashed near Townsend in March, killing the pilot, was flying too low.

The National Transportation Safety Board report says pilot Sparky Imeson used poor judgment in failing to maintain enough altitude before his plane crashed on March 17 at the base of a mountain range near Canyon Ferry Lake.

In a report released Tuesday, the NTSB said it found no mechanical issues with the aircraft and said the plane collided with trees before hitting the ground.

Friends said Imeson was trying to photograph the site where he had survived a plane crash two years earlier. He had taken off from Bozeman and was scheduled to fly to Helena.

Imeson, who was 64 and a native of Jackson, Wyo., was an experienced pilot, author and instructor known for his expertise in flying over mountainous terrain.