A French court cleared both companies of corporate manslaughter in 2023, following a historic public trial over the loss of Air France flight 447, which vanished from radar screens while en route from Rio de Janeiro on June 1, 2009.
Prosecutors appealed the outcome and families of many of the victims have pledged to fight to establish criminal wrongdoing in weeks of technical expert evidence to be reviewed in the Paris appeals court between now and late November.
Dozens of relatives rose in unison and stood in silent mourning as a French appeals judge read out the names of each of the 228 people who died when their Airbus A330 passenger jet plunged into the ocean during a night-time equatorial storm.
The chief executives of both the plane manufacturer and the airline paid tribute to the suffering of bereaved families but denied any criminal responsibility for the crash.
"It is forever engraved in our memories," Air France CEO Anne Rigail told the packed high-windowed courtroom.
"Any accident is a failure," Airbus CEO Guillaume Faury told the panel of three judges, adding that the aviation industry was constantly examining itself to keep flying as safe as possible.
After a two-year search for the A330's black boxes, French investigators found that the pilots had mishandled the temporary loss of data from iced-up speed sensors and pushed the jet into an aerodynamic stall, or free fall, without responding to alerts.
But the first trial more than a decade after that also shed light on discussions even before the accident between Air France and Airbus about growing problems with the sensors, or "Pitot probes", that generate speed readings.
Following nine weeks of evidence, a Paris judge listed four acts of negligence by Airbus and one by Air France, but found that these were not enough under French criminal law to establish a definitive link to the loss of the jet during a midnight storm.
Prosecutors and lawyers for families will use weeks of appeal hearings to try to persuade judges that there was a direct link between the previously identified negligence and the crash.
"It is painful for the families to reopen everything 16 years later, but it is essential to keep going and demonstrate that there was criminal culpability," said Sebastien Busy, a lawyer for one of the main associations of victims' relatives.
"If you take one of those acts of negligence away, then the accident would never have happened."
