American Airlines may be forced to cancel thousands of flights during Christmas week because of a major scheduling mishap

Alexandre Meneghini/Reuters

People walk past an American Airlines office, which is not operational yet, in Havana, Cuba

• Thousands of American Airlines flights may not have pilots during the last two weeks of December.
• The shortage is occurring because a glitch in the company's scheduling system allowed for too many pilots to take off at the same time.
• A spokesperson for the Allied Pilots Association calls the incident a "crisis."

American Airlines is having a nightmare before Christmas.

More than 15,000 American flights between December 17-31 do not yet have pilots because the airline accidentally gave all of its pilots that time off, according to the Allied Pilots Association.

The issue stems from a glitch in the company's scheduling system, the union said.

"Basically there's a crisis at American for manning the cockpits," Dennis Tajer, a spokesman for the union, told Reuters.

Pilots were told about the scheduling problem on Friday, the union said.

A spokesperson for the airline told Bloomberg that the carrier is offering up 150% of its regular hourly wage to pilots willing to pick up certain flights.

"We are working through this to make sure we take care of our pilots and get our customers where they need to go over the holiday," the American Airlines spokesman said.

But the union says that this actually violates its labor pact.

American Airlines did not immediately respond to a request for comment.

This story is developing, check back for updates.