The captain of a Canadian submarine says his thoughts are with the families of 44 Argentine submarine crew members who have been lost in the South Atlantic for 11 days, but he tries not to dwell on the dangers of underwater travel while running his boat.

Cmdr. Peter Chu, the commanding officer of the HMCS Windsor, said he has been following news of the round-the-clock international search for the Argentine submarine, and said it has been "very unsettling" to see his fellow submariners in peril.

"We wish and are praying that their families and friends are being taken care of in this dire state, and a predominantly catastrophic and fairly unpredictable situation," Chu said.

Sub missing since Nov. 15

The Argentine navy said an explosion occurred near the time and place where the sub went missing on Nov. 15, and that even if it's intact its crew may be running out of oxygen.

Defence Minister Harjit Sajjan said Canada has sent a CC-144 Challenger aircraft with equipment to assist with the search and rescue efforts.

He said the twin-engine, long-range jet departed Halifax on Wednesday night in response to a request for assistance from the government of Argentina.

More than a dozen airplanes and ships have been participating in the multinational search despite stormy weather that has caused powerful waves.

Argentine submarine

A woman holds a placard with a message that reads in Spanish: "We are with you, brave ones of the ARA San Juan," in front of the Mar de Plata Naval Base, Argentina, on Nov. 25 where relatives of the missing crew have gathered. (Esteban Felix/AP Photo)

Search teams are ranging across an area of some 480,000 square kilometres, which is roughly the size of Spain.

Chu refused to speculate about what happened to the Argentine submarine.

We're focused on doing our job professionally ... and we're not really dwelling on Hollywood scenarios. - Lt.-Cmdr. Peter Chu

He said all submariners are aware of the risks inherent to their job, but his crew has gone through extensive training to prepare for an emergency situation.

"I think if you're an experienced submariner, I think you're going to accept that our job is dangerous and rely on our training to get us through it," Chu said. "We're focused on doing our job professionally ... and we're not really dwelling on Hollywood scenarios."

30-year-old vessel

Chu said the Canadian Navy does not have deep-submergence rescue vehicles, which are often used in submarine rescues. The U.S. is one of the few countries to have such capabilities, he said, and would deploy its vessels to come to Canada's aid if necessary.

The ARA San Juan is a German-built diesel-electric TR-1700 class submarine and was commissioned in 1985 and was most recently refitted in 2014.

Some relatives of the Argentine crew have lashed out at the navy for its response and for putting their loved ones at risk in a vessel that is more than 30 years old.

Canada's four existing Victoria-class vessels, purchased from the U.K. in 1998, have a reputation for breakdowns and other problems.

'Really feel for them'

Chu said the Windsor regularly undergoes maintenance checks to ensure that the submarine is in "top form" before it sets sail.

On Oct. 5, 2004, an electrical fire tore through the HMCS Chicoutimi while on its maiden voyage to Canada from Scotland.

Lieut. Chris Saunders, a 32-year-old father of two living in Halifax, died in the blaze.

Russian aircraft

A Russian Antonov transport aircraft sits on the tarmac in Comodoro Rivadavia, Argentina, on Nov. 25. Russia sent the Pantera Plus unmanned submersible to help in the search for the missing Argentine submarine. (Maxi Jonas/AP Photo)

Douglas Renken was one of nine sailors treated for smoke inhalation following the deadly fire onboard the Chicoutimi.

Renken said he can "only imagine what hell it is" for the families of the missing Argentine crew.

"Once a submariner, always a submariner," Renken said by phone from his home in Sackville, N.B. "I really feel for them and their families. I absolutely feel for them."