A Transportation Safety Board report released Thursday reveals for the first time how a Sikorsky S-92A chopper with five passengers and two crew members suddenly plunged after takeoff from the SeaRose platform.
It also raised questions about safety oversight and public disclosure.
"This helicopter came within seconds of impacting the water," the board's lead investigator Daryl Collins said in an interview.
"They were extremely lucky that they were able to arrest the descent before that happened, and that they actually came out of the clouds in time to see the water rapidly approaching so that they could apply power to stop the descent.
"It was an extremely close call."
The board found numerous operational, procedural and training issues that contributed to the incident July 23, 2011 as the chopper headed for St. John's.
Collins said the pilot's "rapid" application of a control as the helicopter lifted into cloud cover caused the chopper's nose to rise. As a result, air speed needed to maintain autopilot functions was lost and the helicopter fell as it lost forward momentum, he explained.
The pilot didn't react right away, possibly because of disorientation, before the aircraft dropped from the clouds 60 metres above the sea, Collins said. That's when the flight crew saw the fast-approaching water and the captain corrected the helicopter's position just 11 metres or 38 feet above the waves, says the report.
"The first officer, lacking confidence in his abilities to recover from the inadvertent descent, did not take control of the helicopter, as required by (Cougar Helicopter's) standard operating procedures," it says.
No one was injured in the incident.
Flight crews did not regularly practise recovery from such sudden drops, nor were they trained to recognize or respond to the "subtle incapacitation" that can come from a loss of visual cues in cloud or darkness, says the report.
It says Cougar, which operated the chopper, has since improved training. It now requires that pilots fly a minimum of two flights every 90 days using manual instrument approaches. It has also clarified procedures on use of autopilot and how to recover from similar situations in the air.
Collins stressed that Cougar has a long track record of safe flight off Newfoundland and that it can be difficult to see certain issues until a close call exposes them.
Still, the report notes that potentially valuable information was lost about the occurrence because the chopper's flight recorder wasn't secured right away. It also cites two previous offshore helicopter descent incidents on Aug. 26, 2007 and Nov. 12, 2008 that weren't reported to the board at the time in keeping with aviation regulations.
Cougar issued a statement saying it enhanced its procedures as a result of what happened in July 2011.
The helicopter that nearly went down is the same model that crashed off Newfoundland in March 2009 when its main gearbox failed, killing 17 people. St. John's city councillor Danny Breen's brother Pete, who worked on the SeaRose platform, died in the disaster.
Breen says the report raises questions about why more detail on the July 2011 incident wasn't made public at the time.
"It was kind of put off as a routine situation that was corrected immediately. But obviously, from the report, if that ... description had been given back in July 2011, I think people would have been much more concerned about what happened."
Soon after the botched takeoff, the board that regulates the oil sector off Newfoundland released a brief bulletin on its website.
"On departure from the SeaRose, the aircraft encountered an unplanned increase in pitch and altitude, followed by a decrease in altitude," said the posting by the Canada-Newfoundland and Labrador Offshore Petroleum Board.
"The helicopter crew were able to stabilize the aircraft into a hover position, completed equipment checks, and then continued to St. John's."
The bulletin said the mishap was under investigation by Cougar but little more.
Board spokesman Sean Kelly said Thursday the height to which the chopper dropped "is something that comes from the TSB investigation. C-NLOPB incident bulletins are notifications that an incident has occurred."
But Kelly said the Transportation Safety Board verifies details and makes them public.
Lana Payne, Atlantic director of Unifor, the union representing about 700 offshore oil workers, said that sounds like buck-passing.
"If you want people to have confidence in these helicopters, then when you have a problem like this you need to get out there with it and explain what happened and what you're doing to address it.
"What would have happened had this occurred at night?"
Payne said the incident casts fresh doubt on the oil industry's push to resume flights to and from the offshore after dark. Night flights were suspended in 2010 during a public inquiry into offshore helicopter safety.
Both opposition parties said Thursday's report proves that a stronger, more independent safety regulator is needed.
"I am shocked that we find out only today, and only courtesy of the federal agency, what exactly happened on July 23, 2011 and what exactly Cougar did to help prevent a recurrence," NDP Leader Lorraine Michael said in a statement.
"I think an independent safety authority would have provided ongoing updates in the intervening two years."