American Airlines customers can now choose non-binary gender options when booking flights — but only if they book their flight over the phone or call the reservations team after booking online to have it changed. The non-binary gender options do not currently appear on the airline's online booking process, nor is there a non-binary gender option available when signing up for their frequent flyer program online.

A screenshot of American Airlines' online booking process on December 21, 2019 showing only male and female gender options.

"We recently completed a system update to offer non-binary gender selections," American Airlines confirmed to CBS News. "Taking care of our customers and team members is what we do, and we are glad to be able to better accommodate the gender preferences of our travelers and team members."

Customers can now choose to have the gender designated on their boarding passes read "U" or "X."

American Airlines made the change in order to better meet TSA requirements. Some U.S. states and foreign countries provide ID's with a gender of U or X and, as part of TSA's existing requirements, airlines must obtain a first name, middle name, last name, gender and date of birth for all passengers. Therefore, if a passenger wishes to choose the non-binary gender options, it still needs to match the gender displayed on their ID.

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The non-binary options will be available when booking online sometime in early 2020.

United Airlines was the first airline to add a non-binary gender option for booking flights. Since March, their customers have been able to identify themselves as male, female, undisclosed or unspecified. They can also use the title "Mx." in lieu of "Mr.," "Mrs." or "Ms."

American Airlines has not said if they will also allow non-binary gender titles. When questioned about non-binary gender titles on Twitter, American Airlines said it can be updated over the phone or through a direct message on Twitter.