NEW YORK (BLOOMBERG) - Southwest Airlines was sued by a passenger who witnessed the "horror" when an exploding engine part shattered a cabin window 20 minutes into a flight from New York-LaGuardia airport.

Lilia Chavez says she was sitting three rows behind the shattered window and saw other passengers struggle to pull a woman back into the cabin after she had been partially sucked through the window. She died.

Chavez claims she is suffering from post-traumatic stress disorder and anxiety, among other injuries.

She is asking for compensatory and punitive damages for the carrier's reckless misconduct and disregard for her safety and well-being, according to a complaint filed on Thursday (April 26) in federal court in Philadelphia.

Representatives of Southwest did not immediately respond to a request for comment on the lawsuit.

The airline said last week it is providing US$5,000 (S$6,600) cheques and US$1,000 travel vouchers to passengers who were on board the April 17 flight to Dallas.

The lawsuit also names CFM International, a joint venture between General Electric's aviation business and a division of France's Safran, which built the plane's engine.

The National Transportation Safety Board is trying to determine why a fan blade tore loose, shattering the CFM engine and shooting fragments at a wing and the fuselage of the Boeing 737-700.

Federal investigators found signs of metal fatigue where the blade broke off.

Southwest said it can't comment on any pending litigation.

"Our focus remains on working with the NTSB to support their investigation," the carrier said in an email.

"The safety and security of our employees and customers is our highest priority at all times."