Christmas is the busiest travel time of the year. Millions of people fly, drive, or take the train to visit family for the holidays. Flying can be especially stressful when you factor in all the security checks, the packing restrictions, and the sheer number of people in the airport.

Booking your flights is always a hassle, because you want the best deal with the most amount of time away. This involves a ton of research and planning, especially if you have to take time off from work.

The big airlines, like Delta, American Airlines, Jet Blue, and United, are counted on to get families to and from their holiday destinations without a problem. But now, American Airlines has announced an internal error that could potentially ground 15,000 flights this holiday season.

It seems that American Airlines has granted every single American Airlines pilot vacation time over the Christmas holidays, meaning there's no one to fly the planes. The airline is calling it a computer error, blaming their app for the issue.

Trip Trade, a scheduling app used by the company, is where pilots can see flights which are available to drop and which ones are locked in. Apparently, every flight between December 17th to December 31st was available to drop, so everyone did.

"It wasn't a failure to assign [pilots], it's just no one said, "˜I want to work Christmas,'" said one American Airlines pilot, who chose to remain anonymous.

American Airlines doesn't believe it to be an issue.

"Out of the 200,000 flights American will operate in December, only a few hundred are currently unassigned to pilots," they said in a statement.

But this sentiment is not echoed by the Allied Pilots Association.

"For them to say that... we're confused," said Captain Dennis Tajer, the Allied Pilots Association union's communications chair. "I pulled data today. Currently there's thousands of unassigned flights, so I'm not sure what they're looking at. All our pilots can pull the same data."

The issue is going to be finding pilots who actually want to work on Christmas, which could prove to be difficult. Tajer says that shifting around their schedules to cover these flights could cost pilots "premium" flights they've already been assigned, which pay 150%, because of regulations on flying time. That doesn't mean it'll be impossible, though.

"I think there's going to be some pilots who don't have young kids who are going to fly for time-and-a-half," said the American Airlines captain. "But I ain't gonna work on Christmas "” sure as hell not for time-and-a-half. Double time "” I'd probably go do that."

American Airlines says they will do their best to avoid cancellations.

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

Do you have a trip booked with American Airlines this Christmas?