French magistrates investigating the 2009 crash of a flight from Rio de Janeiro to Paris, in which 228 people died, have ordered charges against Airbus and Air France be dropped.
Air France Flight 447 plunged into the Atlantic during a storm on June 1 that year, after a malfunction in its pitot tubes, which enable pilots to monitor their speed.
The sources said the magistrates had ordered that manslaughter charges against Airbus and Air France be dropped.
Magistrates Nicolas Aubertin and Fabienne Bernard said they found the accident was caused by a unique combination of factors that "brought up evidence of previously unperceivable dangers".
They said they could not ascribe fault to the companies in what appeared to be a case of pilot error.
Representatives of the victims' families called the decision an insult to the memory of their loved ones and said they would appeal against it.
"How can one not think that this decision is guided by economic interests larger than those of justice?" they said.
Olivier Morice, lawyer for several victims' relatives, indicated his surprise that Air France did not even receive censure.
Mr Morice said he would appeal against the "very disputable" decision.
Nelsonfaria Marinho, chairman of the Brazilian relatives' association, said he was indignant at an "absurd and corporatist decision".
An investigation is continuing in Brazil, which lost 59 nationals in the crash.
It was the worst crash in Air France's history and prompted reviews of pilot training after it emerged that one of the co-pilots reacted incorrectly when the plane stalled after the speed sensors froze.
It took two years to find the wreckage of the Airbus A330, which was eventually found by remote-controlled submarines at a depth of 3,900 metres.
Magistrates later charged Air France and Airbus with manslaughter, but prosecutors in July recommended that only the airline face trial.
They accused Air France of negligence in failing to train its pilots about how to react to malfunctions of the pitot tubes, after several incidents involving the sensors in the months leading up to the crash.
In such cases the magistrates leading the investigation have the final say over prosecutors, but the decision can be appealed by defence or civil plaintiffs.
Since the disaster, pilot training on dealing with unforeseen circumstances has been stepped up in France and other countries.
Aircraft safety has been in the spotlight this year after two crashes involving the 737 Max model from US maker Boeing, which has led to a global grounding of the aircraft.
