Two planes crashed into the North and South towers of the World Trade Center complex in New York City, on September 11, 2001.
A US federal judge has ruled that United Airlines is not responsible for a lapse in airport security during attacks on the World Trade Center on September 11, 2001.
US District Judge Alvin Hellerstein has approved a request on Wednesday to dismiss negligence claims brought by Larry Silverstein, the leaseholder of World Trade Center 7, against United Airlines and its affiliates.
Silverstein argued that United Airlines mismanaged a security checkpoint at an airport in the US state of Maine, which allowed an American Airlines plane to takeoff from its runway and crash into one of the World Trade Center buildings.
He said United was legally responsible for the screening of all passengers and accused it of negligence in failing to prevent the hijacking of the plane.
However, there are still many unanswered questions regarding the attacks, and many believe that the whole incident was an inside job, designed to justify subsequent US-led wars in Iraq and Afghanistan.
Experts lay claim to the fact that the collapse of the World Trade Center appears similar to a controlled demolition, with many architects and scientists maintaining that jet fuel cannot produce enough heat to melt the steel frame of the two buildings.
Four attacks happened in the United States on September 11, 2001. About 3,000 people died in the attacks.
In the worst attack, two planes, an American Airlines Flight 11 and a United Airlines Flight 175, crashed into the North and South towers of the World Trade Center complex in New York City. Both towers collapsed within two hours.