American Airlines was scrambling to avoid thousands of cancelations over the busy holiday travel period after a scheduling glitch left many flights without pilots, the company said.

Some 15,000 flights scheduled between December 17 and 31 are without pilots after a scheduling system hiccup allowed too many pilots to take time off, the American Pilots Association said, according to news reports.

The airline said it will offer pilots 150 percent of their hourly rate to cover affected flights and can also call on reserve pilots to prevent cancelations.

"We are working diligently to address the issue and expect to avoid cancellations this holiday season," American Airlines said in a statement.

"We will work with the APA to take care of our pilots and ensure we get our customers to where they need to go over the holidays."

The scheduling of work, rest and vacation time for pilots and flight crews is subject to strict regulation, requiring airlines to use complex planning tools to manage it.

American suffered a similar problem last year, and in 2015 flight crews due to have vacation time were assigned to fly instead.