Wedoff agreed, saying the brief was not part of a motion requiring a court decision.

Douglas Baird, a bankruptcy professor at the University of Chicago Law School, said Wedoff was correct in striking the brief.

"You can't just say, 'Oh, judge, here's something for you to read,' " he said. "This is a case where United was using a brief as a press release."

The information in the brief could show up in future motions, particularly if the Elk Grove Township, Ill.-based carrier decides to kill its pension plans and needs the data to support its decision, which would require court approval.

The company was disappointed by the judge's decision, United spokeswoman Jean Medina said.

"We believe the information is important to share, so we will continue to do so with our employees, retirees and other stakeholders," she said.

United has said in recent weeks that it is likely to terminate its four pension plans, which the government estimates are underfinanced by $8.3 billion. The Thursday court filing tried to show that the funds are not in such dire shape and that retirees and employees would receive greater benefits than they might have expected if the plans were terminated.

The unions were up in arms about the 100-plus page brief, and the unions representing United's machinists and flight attendants filed an emergency motion asking the court to strike it from the docket. The federal Pension Benefit Guaranty Corp. joined the unions' motion.

All three parties applauded the judge's decision to throw it out.

"Of course, the PBGC is very pleased about Judge Wedoff's decision to disallow this filing," said spokesman Jeffrey Speicher.

If United's plans were terminated, they would represent the largest liability ever for the pension board, which has said it is concerned that other airlines might follow suit.