The inquiry into a deadly Newfoundland helicopter crash resumed Monday, as a lawyer representing oil-company workers asked to question executives why it took nine years to equip such aircraft with emergency underwater breathing devices.

Three oil-company executives gave evidence at the inquiry, which is investigating the crash of Cougar Flight 491 that killed 17 of 18 passengers and crew off the coast of Newfoundland last March.

"We were greatly saddened by the events on March 12," said Trevor Pritchard, general manager of operations for Husky Energy. "There's nothing more important than the safety of our workforce -- and this includes the safe and reliable transportation of our employees to and from the offshore industry."

The Transportation Safety Board is conducting a separate investigation into what may have caused the chopper to drop into the Atlantic about 60 kilometres east of St. John's.

Gary Vokey of Suncor Energy and Paul Sacuta, president of the Hibernia Management and Development Co. also testified on Monday.

Randy Earle, a lawyer for the Communications, Energy and Paperworkers union asked to question the executives on a nine-year interval to install underwater emergency breathing apparatuses in such helicopters

The devices can offer a minute or two of oxygen. Last May they became standard equipment for workers flying to or from oil platforms. The offshore regulator had requested they be installed more than nine years earlier.

Retired judge Robert Wells is leading the inquiry into the helicopter's tragic end.

Since taking helm of the inquiry, the commissioner has gained some understanding of the lives of oil workers, having taken offshore flights himself to learn about the process.

In one instance, he returned to shore by helicopter and saw family members waiting for their oil industry-employed loved ones to return home safely. He calls it a "defining moment."

"The lobby was full of mostly young women with children, babes in arms, and two- and three-year olds walking about," Wells told CTV's Canada AM during an interview from St. John's on Monday morning.

"And that's when it hit me how emotional, not only was the accident, but how emotional is the journey, not only for those who make the journey offshore and return, but for the families. And that in a sense was a defining moment for me."

In November, the inquiry heard testimony from Robert Decker, the sole survivor of the deadly flight. The 28-year-old told the inquiry what it was like to plummet into the icy waters of the Atlantic Ocean and fight to make his way to the surface.

His riveting testimony drew more than 100,000 hits on the inquiry website that day, Wells said, an indication of how much the public wanted to know about what happened on board the doomed flight.

"The atmosphere in the room was quite unlike any atmosphere I've seen in a room before and very, very emotional," Wells said.

"But his testimony was valuable because he talked about the escape aids," said Wells.

Wells said he was struck by Decker's description of his hands, which were rendered "absolutely useless" in the freezing cold water.

A report from the inquiry is due to be released March 31, though Wells has said he will need until September to complete it.

Wells told Canada AM that he expects that the current stage of the inquiry will wrap up by the end of next month.

At that time, the commissioner said he will decide which issues are worth investigating at an in-depth level.

With files from The Canadian Press