Air France and Airbus are on trial on Monday for involuntary manslaughter over the fatal 2009 crash of a Brazil-Paris jet that killed all 228 people on board.

Victims’ families and some aviation experts say the pilots weren’t adequately trained to deal with a loss of speedometer caused by critical equipment freezing in a storm.

Flight AF 447 from Rio de Janeiro crashed into the Atlantic Ocean in the early hours of June 1, 2009 after entering an area near the equator known for severe turbulence.

The Airbus A330 carried 12 crew members and 216 passengers. It was the carrier’s deadliest crash.

It took nearly two years to locate most of the fuselage and recover the “black box” flight recorders.

Air France and Airbus were charged over the course of the investigation, with experts finding the crash was due to error by pilots who were disoriented by so-called pitot speed monitoring tubes frozen over in thick clouds.

However, investigating judges overseeing the case dropped the charges in 2019, a decision that infuriated victims’ families.

Prosecutors appealed the decision and in 2021 a Paris court ruled that there was sufficient evidence for a trial to proceed.

Ophelie Toulliou, who lost her brother on the flight, said it was important “to get the truth out and that the judgments, when deserved, be made.”

“But the message is also intended to make it clear to companies that consider themselves untouchable: ‘You are like everyone else and if you make mistakes they will be punished,'” she told AFP.

The court will hear testimony from dozens of aviation experts and pilots over a period of two months, and each company faces a maximum fine of 225,000 euros ($220,000).

It also analyzes the last few minutes in the cockpit before the plane went into freefall, having entered what is known as an “intertropical convergence zone” that often produces violent storms with heavy rainfall.

Pitot tubes froze in the cold, a problem that had been reported by other pilots – and one that was quickly replaced on planes worldwide in the months following the accident.

“We’ve lost our speed,” a pilot is heard saying in the flight logs, before other gauges erroneously indicate a loss of altitude and a series of alerts appear on the cockpit screens.

The pilots begin to climb and, despite a “STALL” alarm, reach 11,600 meters (38,060 feet).

“I don’t know what’s happening,” one of the pilots is heard saying as the stall begins.

The crash prompted an overhaul of training protocols across the industry, particularly to prepare pilots to handle the intense stress of unforeseen circumstances.

Pilots are now also required to continually practice stall responses on simulators.

“That was the big change after this accident for all civil airlines. Pilots used to learn this in basic training and then never received training again,” an airline executive told AFP on condition of anonymity.

Testimonies are also being heard from some of the 476 family members of the victims who are plaintiffs in the case.

But Nelson Faria Marinho, president of the Brazilian Association of Victims’ Relatives, said: “I don’t expect anything from this process.”

“Even if there is a conviction, who will be punished? The CEOs? They were switched at Airbus and Air France a long time ago,” he told AFP during an interview at his home in Rio.

He is represented by former French pilot Gerard Arnoux, who has counseled several victims’ families and has written a book entitled Rio-Paris Not Responding: AF447, the Crash That Shouldn’t Have Happened.