NEW YORK — United Airlines cannot be held responsible for the hijacking of an American Airlines flight and the collapse of a third World Trade Center building after the twin towers fell in the Sept. 11, 2001, attacks, a federal judge ruled Wednesday.

The airline was not responsible for the collapse of 7 World Trade Center because it had no connection to American Airlines Flight 11 or its hijackers, except that it had shared responsibility for a security checkpoint in Portland, Maine, that screened two of the terrorists, US District Judge Alvin Hellerstein said.

The corporation that owns 7 World Trade Center sued various aviation defendants, saying their negligence led to the building’s destruction.

Other than shared authority for the lone security screening checkpoint, ‘‘United had no connection to Flight 11 or its hijackers,’’ the judge said.

Bud Perrone, a spokesman for Silverstein Properties, said the plaintiffs were disappointed but looked forward to their prospects in a different lawsuit against United over security lapses involving United Flight 175.