By Steve Quinn
JUNEAU Alaska (Reuters) - A cargo plane's crash into a mountainside in southwest Alaska last year was caused by failure to maintain a safe altitude, which was the fault of an air traffic controller and the two pilots who died in the accident, federal regulators said on Monday.
The Alaska Central Express Air Cargo crashed on March 8, 2013, after striking a "rock outcrop protruding from the snow" outside Dillingham, the plane's destination, according to the National Transportation Safety Board.
The crash took the lives of pilot Jeff Day, 38, and his co-pilot, 21-year-old Neil Jensen.
During stormy weather near Dillingham, Day asked to enter a holding pattern so he could switch to another radio channel and check on runway conditions.
The plane, however, held at an altitude of 2,000 feet, rather than the required 5,400 feet, something the crew should have known, the report said.
"Such a lack of awareness is inconsistent with pilot-in-command responsibilities and company procedures ... during the descent and approach phases of flight," the NTSB report said.
Meanwhile, the air traffic controller's instructions were "ambiguous," the report said, and failed to specify what segment of the approach could be done at 2,000 feet.
"(The controller) did not appropriately monitor the flight's progress and intervene when the airplane descended to 2,000 feet," the report said.
"As a result, the airplane was permitted to descend below the minimum instrument altitudes applicable to the route of flight and enter the holding pattern well below the published minimum holding altitude."
The report notes that the aircraft, a Beech 1900C, had several pieces of navigation equipment that can produce visual and aural terrain warnings. Damage from the crash, however, prevented NTSB inspectors from testing the equipment or determining its settings prior to the crash, it added.
Day had been captain of the Beech 1900 for nearly 18 months, having been with the company for nearly five years, accumulating more than 5,400 hours in the aircraft. Jensen had been with the company four months, racking up 250 hours in that plane.
(Reporting by Steve Quinn; Editing by Daniel Wallis and Eric Walsh)