It sounds like the premise for a zany holiday movie, but it’s real: Over 15,000 American Airlines (AAL) flights between Christmas and New Year’s have no pilot assigned to them due to a computer glitch.

Here’s what happened. American Airlines uses an app called “Trip Trade” in which pilots are assigned flights. Pilots can use the app to shuffle and trade flights to make their own schedules. Flights that are “green” can be dropped or traded at will, and flights that are “red,” the crucial ones, are locked in. Pilots can swap red flights with each other, but they can’t drop them.

Typically, flights during high-volume weeks such as between Christmas and New Year’s are red, but some sort of computer glitch turned all of these flights green.

“All the trips turned green, so everyone dropped trips,” one American Airlines captain told Yahoo Finance. The pilot requested anonymity, citing sensitivity in the ongoing negotiations. “It wasn’t a failure to assign [pilots], it’s just no one said, ‘I want to work Christmas.’”

In a statement to Yahoo Finance, the airline said it expects to avoid cancellations this holiday season via reserve pilots and paying pilots who pick up “certain open trips” 150% of their hourly rate, “as much as we are allowed to pay them per the contract.”

The Allied Pilots Association union told pilots that American Airlines has not guaranteed to pay 150% for all flights during this time, though negotiations were ongoing. The APA did not immediately respond to Yahoo Finance’s requests for comment.

Even if 150% of the hourly rate is agreed upon for all trips, it may not be enough to convince pilots to fly.

“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.”

An ongoing issue

The union has been trying to get increased holiday pay for the past few contracts, and is taking this snafu as an opportunity to ask again. But according to the pilot, American Airlines is not interested in renegotiating.

“The company isn’t interested in making an adjustment to the contract, because it’d cost them,” the American Airlines captain said. “They‘d rather just throw it to chance.”

For the pilots, the main attitude on the ground — or in the air — seems to be one of circumspection. Since the flights were all green in the app, most pilots are not on the hook to fly when they don’t want to fly, a positive result given the lack of the holiday pay bumps they’ve asked for.