DALLAS—A major airline introduced Boarding Group 11 on Thursday. It is a new tier for passengers who would like to board after the aircraft has already departed.

"Customers told us the boarding process felt crowded," said customer experience officer Brent Kowalski. "Group 11 solves that completely. There is no one at the gate, and no plane either."

Group 11 passengers keep every benefit of their ticket, including a seat assignment, a printed boarding pass, and an announcement over the gate speaker confirming the flight is "now closed."

The airline says the new group is already its fastest-boarding tier. The average boarding time is zero minutes.

"I've been in Group 11 all week," said frequent flyer Dennis Albright, standing at Gate C14. "I haven't gone anywhere, but I've never felt less rushed."

Upgrades from Group 11 to Group 10 cost $39 and also do not guarantee a seat on the plane.

At press time, the airline had announced Group 12, which lets passengers board a flight that has not yet been scheduled.