Federal officials say that American Airlines contributed only $6.5 million of the $100 million it was supposed to pay into employee pension plans this week.
The Pension Benefit Guaranty Corp. called the underpayment "a disturbing development."
"The company has determined this is the appropriate course of action for the quarterly contribution amount due by Jan. 15, 2012. This action allows the company to preserve cash," said Sean Collins, with American Airlines.
American and its parent company filed for bankruptcy protection in November.
The director of the pension-insurance agency has warned American not to terminate its pension plans.