American and United airlines say they will extend their deadlines on unused flight credits, pushing the ability for customers to utilize tickets that went unused last year into 2022.

The two major carriers join Southwest, which had already been allowing customers to wait until next year to use any tickets lost in 2020 when the coronavirus pandemic brought air travel to a virtual standstill.

In fact, according to Bloomberg News Service , U.S. carriers had $11.7 billion in unused tickets at the end of 2020.

At one point last year, capacity on U.S. flights plummeted to just 10 percent. It has slowly worked its way back to 50 percent, thanks to the vaccines that began in December and the health and safety protocols undertaken by the airlines.

The news service noted that about 11 percent of all open, unused tickets are now set to expire this year, down from 55 percent as of Jan. 29, according to TripActions, a corporate travel management firm.

“It’s pretty clear that the shift is a reflection of the fact that airlines are adjusting dates to accommodate customers, both business and leisure, in this fluid travel environment,” said Kelly Soderlund, a spokeswoman for TripActions.

Conversely, flight-credit expirations in 2022 have increased to 89 percent from 45 percent.

Most credits traditionally expire 12 months after a ticket is purchased, and carriers extended expiration deadlines last year as air travel plunged. But many were set to expire this year – and some already have – as millions of would-be flyers continue to stay off planes.

Southwest extended expiration dates early in the pandemic through Sept. 7, 2022 for those who booked travel or had credits that would have expired between March 1 and Sept. 7, 2020.