Paris (CNN) A French widow has filed a lawsuit against US aircraft manufacturer Boeing for $276 million in damages over the crash of an Ethiopian Airlines 737 Max 8 in March, which killed all 157 people on board -- including her husband.

Frenchwoman Nadege Dubois-Seex, whose husband Jonathan Seex died in the accident, filed the suit against Boeing in Chicago, where the company is headquartered.

Nadege Dubois-Seex (right) at a Paris press conference alongside a portrait of her late husband.

"It is a tragedy which, by definition, could have been avoided, because it had already happened five months before. How could they stay deaf to this warning?" Dubois-Seex told reporters in Paris on Tuesday, referring to another Boeing 737 Max 8 in Indonesian company Lion Air's fleet that crashed last October, leaving 189 people dead.

Boeing admitted Saturday that it had to correct flaws in the flight simulator software used to train pilots on the 737 Max, following the two deadly crashes that killed a total of 346 people. The aerospace company did not share when or how the flaws were discovered, however.

The admission of the simulator-software flaw comes amid intense scrutiny on Boeing and the design of its 737 Max. The plane's MCAS software, which pushes the nose of the aircraft down if it senses an imminent stall, is believed to have played a role in crashes of Lion Air and Ethiopian Airlines jets.

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