A French court on Monday acquitted Air France and plane manufacturer Airbus in a trial over the 2009 crash of a Rio-Paris flight in which 228 people lost their lives.
The court said that even if "errors" had been committed, "no certain link of causality" between those shortcomings and the accident "could be proven".
The two France-based companies went on trial in October to determine their responsibility for the worst aviation disaster in Air France's history, with 216 passengers and 12 crew members losing their lives.
The two companies had been charged with involuntary manslaughter. Both denied the charges.
"We expected an impartial judgement, this was not the case. We are disgusted," said Daniele Lamy, president of the association which represents the families of victims.
"All that remains of these 14 years of waiting is despair, dismay and anger," she added.
The hearings in Paris centred on the role of defective so-called Pitot tubes, which are used to measure the flight speed of aircraft.
The court heard how a malfunction of the tubes, which became blocked with ice crystals during a mid-Atlantic storm, caused alarms to sound in the cockpit of the Airbus A330 and forced the autopilot system to disengage.
Technical experts highlighted how, after the instrument failure, the pilots put the plane into a climb that caused the aircraft to lose upward lift from the air moving under its wings, thus losing altitude.
Companies blame pilot error
Air France and Airbus have blamed pilot error as the main cause for the crash.
Lawyers for the families have argued that both companies were aware of the Pitot tube problem before the crash, and that the pilots were not trained to deal with such a high-altitude emergency.
The court said Airbus committed "four acts of imprudence or negligence", including not replacing certain models of the Pitot tubes that seemed to freeze more often on its A330-A340 fleet, and "withholding information" from flight operators.
The court said Air France had committed two "acts of imprudence" in the way it disseminated an information note on the faulty tubes to its pilots.
But there was not a sufficiently strong causal link between these failings and the accident to prove that an offence had been committed.
