A French judge has placed Continental Airlines under judicial investigation in connection with the Concorde crash that killed 113 people in 2000.
Passengers never regained full confidence in Concorde's safety
The airline is being investigated for "involuntary homicide and injuries".
It follows an official report in December which blamed the accident on a metal strip that fell off a Continental jet prior to the Concorde's take-off.
Under French law, a judicial investigation is normally a first step towards possible criminal charges.
If charges are brought and Continental found guilty, the US airline could face huge claims for damages.
A Continental lawyer denied the airline bore any responsibility.
"Our defence is that we did not commit any error," said lawyer Olivier Metzner.
"In the course of this process, we will do everything, provide all the missing elements of this matter, to show that Continental Airlines is not responsible for the Concorde crash.
"The American authorities investigated the role of Continental Airlines and concluded that Continental did not commit any errors whatsoever in the case of Concorde's crash."
The Air France Concorde caught fire and crashed soon after take off from Paris' Charles de Gaulle airport on 25 July, 2000.
A French public prosecutor said in December that one of Concorde's wheels burst after hitting a strip of metal that had fallen off a Continental DC-10 plane a few minutes earlier.
Fragments from the tyre then punctured the Concorde's fuel tanks, causing the fire.
The public prosecutor said there was "a direct causal link" between the plane hitting the strip of metal and the bursting of one of its tyres.
He also highlighted an "important defect" in the design of Concorde, saying its fuel tanks did not have sufficient protection from debris in the event of a burst tyre.
All Concorde jets - both Air France's and those flown by British Airways - were grounded for more than a year following the crash, before being taken out of service for good in 2003.