PARIS (AP) — Nicolas Toulliou had just proposed marriage to his girlfriend. Nelson Marinho Jr. was heading off on a new oil exploration job. Eric Lamy was about to celebrate his 38th birthday.

They were among 228 people killed in 2009 when their storm-tossed Air France flight from Rio de Janeiro to Paris slammed into the Atlantic. After more than a decade of legal battles, their families have a chance at justice in a courtroom.

Aviation industry heavyweights Airbus and Air France are charged with manslaughter in a trial that opens Monday over the crash of Flight 447 on June 1, 2009. The worst plane crash in Air France history killed people of 33 nationalities and had lasting impact, leading to changes in air safety regulations, how pilots are trained and the use of airspeed sensors.

But it almost didn’t come to trial. The companies insist they are not criminally responsible, and Air France has already compensated families. Investigators argued for dropping the case, but unusually, judges overruled them and sent the case to court.

“We made a promise to our loved ones to have the truth for them and to ensure that they didn’t die for nothing,” Ophelie Toulliou, whose 27-year-old brother Nicolas was killed, told The Associated Press. “But we are also fighting for collective security, in fact, for all those who board an Airbus every day, or Air France, every day.”

She said the companies present themselves as “untouchable,” and that Airbus made no effort to address families’ concerns. “For them, we are nothing. They did not lose 228 people. They lost a plane.”

Few families in Brazil, which lost 59 citizens in the crash, can afford to travel to France for the trial. Some feel the French justice system has been too soft on Airbus and Air France — two industrial giants in which the French government has an ownership stake.

The trial is expected to focus on two key factors: the icing over of external sensors called pitot tubes, and pilot error.

The Airbus A330-200 disappeared from radars over the Atlantic Ocean between Brazil and Senegal with 216 passengers and 12 crew members aboard. The first debris was only spotted at sea five days later. And it wasn’t until 2011 that the plane — and its black box recorders — were located on the ocean floor, in an unprecedented search effort at depths of more than 13,000 feet.

France’s air accident investigation agency BEA found that the accident involved a cascading series of events, with no single cause.

As a storm buffeted the plane, ice crystals present at high altitudes disabled the pitot tubes, blocking speed and altitude information. The autopilot disconnected.

The crew resumed manual piloting, but with erroneous navigation data. The plane went into an aerodynamic stall, its nose pitched upward. And then it plunged.

The pilots ”did not understand what was happening to them. A difficulty of interpretation, in an all-digital aircraft like all the aircraft in the world today — well, it’s easy to be wrong,” said Gerard Feldzer, a former pilot and pilot trainer for Air France.

He said he and pilots around the world asked themselves afterward “if it had been me, would I have acted in the same way? It has been a very difficult question to answer.”

No one risks prison in this case; only the companies are on trial. Each faces potential fines of up to 225,000 euros — a fraction of their annual revenues — but they could suffer reputational damage if found criminally responsible.

Nelson Marinho, whose son Nelson Jr was killed, is angry that no company executives will be tried.

“They have changed various directors, both at Airbus and Air France, so who will they arrest? No one. There won’t be justice. That’s sadly the truth,” Marinho, a retired mechanic who leads a support group for victims' families, told The AP.

Air France is accused of not having implemented training in the event of icing of the pitot probes despite the risks.

In a statement, the company said it would demonstrate in court "that it has not committed a criminal fault at the origin of the accident” and plead for acquittal.

Air France has since changed its training manuals and simulations. It also provided compensation to families, who had to agree not to disclose the sums.

Airbus is accused of having known that the model of pitot tubes on Flight 447 was faulty, and not doing enough to urgently inform airlines and their crews about it and to ensure training to mitigate the resulting risk.

An AP investigation at the time found that Airbus had known since at least 2002 about problems with pitots, but failed to replace them until after the crash. The model in question — a Thales AA pitot — was subsequently banned and replaced.

Airbus blames pilot error, and told investigators that icing over is a problem inherent to all such sensors.

“They knew and they did nothing,” said Danièle Lamy, president of an association of victims' families that pushed for a trial. “The pilots should never have found themselves in such a situation, they never understood the cause of the breakdown and the plane had become unpilotable."

Lamy lost her son Eric a few days before his 38th birthday. She has struggled ever since to find out the truth.

“The plane had sent messages to the ground about the problem but had not warned the pilots. It’s as if you were driving a car at 130 (kph, about 80 mph), your brakes were no longer working but the car sent the alert to the mechanic and not to the driver,” Lamy told the AP.

She is among 489 civil parties to the trial, which is scheduled to last through December.

The crash forced Airbus and Air France to be more transparent and reactive, Feldzer said, noting that the trial will be important for the aviation industry as well as for families.

“The history of aviation security is made from this, from accidents," Feldzer said.

___

This story corrects the type of plane to A330-200 and corrects the spelling of Toulliou's last name.

___

Vaux-Montagny reported from Lyon, France. David Biller in Rio de Janeiro and Angela Charlton in Paris contributed.

Copyright 2022 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.