U.S. Navy salvage drone to search for missing Canadian helicopter

A remotely-operated U.S. Navy submersible will search the ocean floor off Greece for the wreckage of a Canadian air force maritime helicopter and its missing crew members.

The CH-148 Cyclone went down as it was approaching HMCS Fredericton in the Ionian Sea following a surveillance training mission on April 29.

The salvage operation will get underway closer to the end of the month, said Lt.-Gen. Mike Rouleau, who is in charge of overseas and domestic Canadian Forces operations.

"Speed in this search and recovery is very important for a number of reasons," Rouleau said Monday. "The first is for the families. The second relates to our [Canadian Armed Forces] ethos — we do not leave our fallen behind. And the third is, the environment will degrade [crash] evidence over time."

Location of wreckage is known

A mixed team of Canadian and American naval specialists will be aboard the recovery vessel to oversee the operation.

Rear-Admiral Craig Baines, the commander of Canada's East Coast fleet, said the military has a clear idea of the crash location and the Cyclone is equipped with an underwater emergency beacon that continues to transmit for up to 30 days.

He said the signal can only be picked up by a nearby ship; once the salvage vessel arrives, he said, it should be able to zero in on the location.

Watch | Rear-Admiral Baines describes the challenges facing the salvage team

The wreckage may have been moved around by underwater currents.

Both Baines and Rouleau said the recovery operation will continue for as long as it takes to retrieve the remains of the aircrew and one sailor still missing in as much as 3,000 metres of water.

"We will remain at the site until we are satisfied that we have recovered all that we can," said Rouleau, who would not put a timeline on the length of the recovery operation.

The remains of Sub-Lt. Abbigail Cowbrough of Nova Scotia were retrieved on the day of the accident, along with the partial remains of Capt. Brenden Ian MacDonald.

Those still missing are Capt. Kevin Hagen from Nanaimo, B.C.; Capt. Maxime Miron-Morin from Trois-Rivieres, Que.; Sub-Lt. Matthew Pyke from Truro, N.S.; and Master Corp. Matthew Cousins from Guelph, Ont.

The Cyclone was within minutes of landing on the frigate when it inexplicably crashed in full view of crew members on the warship, Baines said.

It had passed the ship after taking photos and was repositioning to conduct what's known as a "deck hoist" operation — the lifting and lowering of personnel and equipment by the aircraft — when the crash occurred, he added.

Modules from the flight data recorders were found almost immediately after the accident, but they are designed to break away from the aircraft and float to the surface.

Maj.-Gen. Alain Pelletier, who oversees joint air operations, would not say what information may have been gleaned from the recorders, but did indicate that the Cyclone fleet remains under an "operational pause."

He refused to speculate on a possible cause. Defence Minister Harjit Sajjan suggested recently the investigation could take a year or more.

Board of inquiry underway

Rouleau said that, in addition to the flight safety investigation, two other administrative probes are underway or are about to be launched. One of them is a summary investigation to establish the status of the missing crew, which will aid families in the estate planning process.

The other is detailed military technical investigation, known as a board of inquiry, which looks at whether military procedures or equipment were to blame.

Watch | Lt.-Gen. Rouleau: 'We do not leave our fallen behind'

Given the depth at which the wreckage can be found, defence expert Michael Byers said the Canadian military was left with few options.

"There are only a few manned submersibles that can go that deep," he said.

"I'm not sure a manned vehicle would prove much of an advantage in this situation. And technology has advanced with regards to remotely operated, deep sea submersibles."

Experts have been wondering whether a salvage operation is possible in the Ionian Sea, known for its depth and underwater canyons. A few hundred kilometres due south of the crash site is a region known as the Calypso Deep, the deepest point in the Mediterranean at 5,267 metres (17,280 feet).