A man was struck by a plane and suffered severe head injuries last week at a base camp on the frozen Beaufort Sea for a Navy submarine exercise, according to Alaska-based federal investigators.

The National Transportation Safety Board released a preliminary report Tuesday on the March 20 incident at Ice Camp Skate, the Navy’s base camp for Ice Exercise 2018 (ICEX) roughly 140 miles north of Deadhorse. The Navy said in a statement on ICEX that the camp was used to coordinate three nuclear attack submarines – two U.S. and one British – as they conducted five weeks of operations beneath the Arctic Ocean ice cap.

According to the NTSB report, the incident occurred at about 7:45 p.m., as a de Havilland DHC-6 Twin Otter operated by Homer-based Bald Mountain Air Service was taking off along “an airstrip on the sea ice that was lined on both sides with snow berms.” The Twin Otter’s captain said that although skies were clear, the sun was low and “flat light conditions” were in effect.

Clint Johnson, the NTSB’s Alaska chief, said Tuesday that the injured man – a civilian employee of the Navy’s Arctic Submarine Laboratory – told the NTSB he had arranged with the flight crew to take a photo during the Twin Otter’s takeoff. As the plane took off, he stood behind a berm on the left side of the airstrip.

“His intent was to get a photograph for his kids,” Johnson said. “He was going to be leaving the ice very, very soon, and he wanted to get a picture of their little LEGO guys on the berm with the plane in the background.”

When the plane took off, the captain told the NTSB, the plane “veered slightly to the left of centerline” and he corrected it by applying differential power to the plane’s twin engines. As the plane became airborne, he lowered the nose “to remain within ground effect and gain airspeed before initiating a climb.” Soon afterward, he began to make a left turn.

“During the turn, both pilots said they heard a loud thump, which was immediately followed by an aileron control anomaly,” the report read. “The captain reported that he continued the left turn and subsequently entered a left downwind traffic pattern for an emergency landing to the north. The captain said that after landing, both pilots saw the pedestrian lying near a snow berm on the left side of the airstrip.”

According to the report, the injured man suffered “serious head and neck injuries” in the collision.

A Navy statement on the incident said the injured man was initially flown to Prudhoe Bay by aircraft at the camp, then medevaced on to Anchorage.

“Based on an assessment by [medical staff], the employee was transported to Providence Alaska Medical Center in Anchorage for a more thorough assessment and care,” Navy officials wrote. “He is in good condition and expected to make a full recovery.”

The injured man told the NTSB that when the plane took off, “it did not climb as quickly as it had during previous departures.”

“The pedestrian said that the last thing he remembered before the collision was seeing the airplane's left wing getting lower to the ground as the airplane continued to accelerate toward him,” the report read. “The next thing he remembered was waking up in the medevac helicopter.”

The Twin Otter had been carrying two crew and three passengers plus cargo at the time of the incident, Johnson said, but no concerns about the aircraft’s weight and balance have initially been discovered.

NTSB staff in Anchorage have reviewed cockpit audio from the Twin Otter, as well as a video of the collision recorded by the Arctic Submarine Laboratory.

Although ICEX has concluded, Johnson said Bald Mountain was working with its insurers on a recovery plan for the $2.5 million Twin Otter – now roughly 150 miles from Deadhorse as the camp's ice floe continues to drift.

“As of yesterday, everything is off the ice with the exception of the airplane – the airplane is still there,” Johnson said.

Johnson emphasized that the investigation remains in its preliminary stages, with no conclusions about the incident initially made. He said it was Alaska’s second instance of a plane striking someone on the ground in the last few years, after a 2014 incident near Dillingham in which a pilot was convicted of assault after his plane’s floats struck a boater and left him with brain injuries.

“It was a very serious event, but it could have been much, much worse,” Johnson said.

A statement from Bald Mountain Air Service Tuesday afternoon said staff were informed of the incident at about 8 p.m. on March 20. The company immediately notified both the NTSB and the Federal Aviation Administration.

"The pilots involved were placed on administrative leave pending the results of mandatory drug testing and further investigation by the involved agencies," company officials wrote.

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