Updated

A federal judge began listening to testimony Monday that will help him decide whether the owners of the World Trade Center buildings destroyed in the Sept. 11 attacks can pursue billions of dollars in damages from aviation companies linked to the hijacked planes.

U.S. District Judge Alvin K. Hellerstein in Manhattan plans to announce his decision from the bench as soon as several witnesses conclude testifying in the trial expected to last about three days.

The buildings' owners, World Trade Center Properties, have already received nearly $5 billion in insurance proceeds.

Lawyers for the owners argued during opening statements that the money they already have received does not preclude them from separately pursuing damages against aviation companies.

Attorney Roger Podesta, speaking for companies including United Airlines Inc., US Airways Inc., American Airlines Inc. and its parent company, AMR Corp., said the $3.5 billion being sought for destruction of the twin towers and a third skyscraper would amount to double compensation.

He said an $8.5 billion total recovery would be more than 2 1/2 times the fair value of the buildings that fell.

Attorney Richard Williamson, representing World Trade Center Properties, said accounting and construction experts had assessed damages of at least $7.2 billion from the Sept. 11, 2001 attacks.

"This did not just come out of a hat." he said of the damage figures. "You can't just say, 'I have economic loss.'"

The trade center owners say it has cost more than $7 billion to replace the twin towers and more than $1 billion to replace the third trade center building that fell.

The trial's first witness was Michael S. Beach, a claims expert hired by the aviation companies who spent hours explaining to the court how the loss was calculated.

In court papers, both sides have accused the other of unfairly characterizing their claims.