NWT/NUNAVUT
A helicopter pilot from the Canadian Coast Guard Ship Amundsen likely didn't realize how low he was flying before crashing into the icy waters of the M'Clure Strait on Sept. 9, 2013, according to a Transportation Safety Board report released last week.

The wreckage of the Coast Guard helicopter that crashed in the M'Clure Strait on Sept. 9, 2013 was retrieved on Sept. 26, 2013. - photo courtesy of Transportation Safety Board of Canada

"There is a strong probability that while over the open water, the pilot experienced a lack of the visual cues required to judge altitude, which led to controlled flight into terrain," the report, released Dec. 7, stated.

The crash killed Daniel Dube, the helicopter's pilot, Marc Thibault, commanding officer of the Canadian Coast Guard Ship Amundsen and Klaus Hochheim, an Arctic scientist with the University of Manitoba.

The helicopter took off from the Amundsen just after 4:30 p.m. with the three men on board. The group was performing ice measurements and surveying the best route from Resolute Bay, where the ship was anchored, to the next research station west of Banks Island, the report stated.

At 5:38 p.m., Dube notified the ship that they would be arriving in about 10 minutes. Five minutes later, the helicopter crashed. The TSB investigation found that although the weather was good at the time of the flight, the water's calmness would have made it appear mirror-like.

"This situation affects visual references for the pilot and can be extremely dangerous, especially when flying close to the surface," the report stated. "If clouds or ice floes are reflected from the water surface, the resulting perception of being at a higher altitude may lead even experienced pilots to descend, resulting in ... accident."

All of the men were wearing immersion suits but all three were found full of water.

Dube was not wearing his lifejacket when he was found but it had been fully inflated.

Thibault was found with his lifejacket on but not inflated and Hochheim was wearing his partially inflated.

All three are believed to have drowned as the result of cold incapacitation, which would have made them too weak to keep their airways out of the water.

"It is highly unlikely that the victims' immersion time was long enough to induce severe hypothermia and cold-induced ventricular fibrillation," the report stated. "However, the victims were definitely immersed long enough to cause considerable, if not complete, cold incapacitation which would have made it impossible for them to maintain their airway above the water line while not wearing a (lifejacket), or while wearing one that was improperly inflated."

At the time, the ship's Shipboard Helicopter Information and Procedures Manual stated staff must perform a communications search if contact hadn't been made with the helicopter during a 15-minute period or during the next scheduled communication time.

A search and rescue operation would begin if contact still wasn't made within the following 15 minutes.

Dube was expected to let the ship's crew know at about 5:47 p.m. that he was preparing to land. When he failed to contact the ship at that time, crew should have begun its communications search by 5:48, according to the report.

If that procedure had been properly followed, a search and rescue operation would have been underway shortly after 6 p.m.

But according to the TSB report, the Amundsen had been equipped with a new Flight Following System (FFS) that season and the crew was unfamiliar with how it worked.

When the crew checked the helicopter's position at 6:05 p.m., the system showed that the helicopter was 3.2 nautical miles from the ship. Crew members didn't realize the timestamp on the information had been made more than 20 minutes before.

That meant the search and rescue operation didn't began until 6:24 p.m.

The report states the search and rescue operation could have begun earlier and that an alarm system would have notified the crew that the helicopter was overdue, but it notes that even this might not have been enough time to save the men.

The crash investigation has led to new safety protocol, including better training, new personal locator beacons that are easier to use and new regulations requiring helicopter passengers to wear thermal-protective immersion suits.

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