Pilot error was the ultimate cause of a sightseeing plane’s crash just over a year ago near Petersburg which left a New Mexico man on board dead, according to the National Transportation Safety Board.

A probable cause report on the June 2, 2013 crash of the deHavilland DHC-2 Beaver seaplane, operated by Pacific Wings LLC, was released Monday by the NTSB. The plane had seven people on board and was flying from Petersburg’s Lloyd R. Roundtree Seaplane Facility just before 3:20 p.m. to a sightseeing trip over the LeConte Glacier via the Horn Cliffs.

One of the plane’s six passengers, Santa Fe, N.M. resident Thomas Rising, 66, was killed in the crash, while Pennsylvania Rev. Frank Allen and his family survived. Allen’s wife Amy and son Ben were treated for serious injuries at Harborview Medical Center in Seattle, but the other four survivors on board received only minor injuries.

In the report, the NTSB cites the unnamed pilot’s failure to maintain airspeed both above trees and while subsequently maneuvering to avoid them, “which resulted in an inadvertent aerodynamic stall/spin and an uncontrolled descent.”

According to the pilot, who had told the NTSB he was flying his third tour and fourth flight of the day, the aircraft was traveling at 80 knots and climbing at about 200 feet per minute shortly before the crash.

“The pilot said that when approaching a mountain pass, he initiated a climb by adding a ‘little bit’ of flap (about 1 pump of the flap handle actuator) but did not adjust the engine power from the cruise power setting,” NTSB officials wrote.

According to the pilot the crash occurred suddenly, in weather a passenger described as consisting of occasional low clouds and good visibility.

“(The pilot) was having difficulty seeing over the cowling due to the nose-high attitude, when he suddenly noticed trees in his flight path,” NTSB officials wrote. “He initiated an immediate left turn; the airplane stalled, and began to drop, impacting the mountainous, tree-covered terrain.”

Both the pilot and a post-crash investigation found that the aircraft had no mechanical issues which would have prevented its normal operation. The passenger who spoke with the NTSB also concurred with that assessment, based on his experience of the crash.

“He reported that the airplane made a left turn, stalled, and then made a sharp left turn right before impact,” NTSB officials wrote. “The airplane seemed to be operating fine, and he heard no unusual sounds, other than the engine speed seemed to increase significantly right before impact.”