Almost a dozen flights scheduled to arrive Thursday night at Denver International Airport were diverted to Colorado Springs due to severe thunderstorms in the Mile High City, said Greg Phillips, director of aviation at the Colorado Springs Airport.

Colorado Springs is the primary diversion spot for flights headed to Denver, Phillips said. Between 9 p.m. and 10:30 p.m., 11 flights from various airlines, including American Airlines, United Airlines and Southwest Airlines, changed course and arrived in the Springs after the National Weather Service in Boulder issued severe thunderstorm warnings for Denver International Airport.

Most of the diverted flights were able to wait out the storm and continue on course, but a handful of aircraft deplaned passengers and provided ground transportation to Denver, Phillips said, noting that is an option airlines often try to avoid.

“It doesn’t lead to a great passenger experience,” he said. “Carriers hope to get back on route.”

Some airlines were required to deplane passengers because they were either approaching the U.S. Department of Transportation’s tarmac delay limit of three hours, or pilots and crews were approaching the Federal Aviation Administration’s maximum limit of flight hours.

Sun Country Airlines beginning route at Colorado Springs Airport

Some passengers sat on planes more than two hours, but Phillips said he was not aware of any flights that hit or exceeded the three-hour limit, adding that while airport staff can help direct aircraft and traffic control to move or park planes, airlines do not allow the airport to offload passengers.

“We will do everything we can to help out,” Phillips said.

Frontier Airlines was among the commercial carriers that unloaded flights Thursday at the Colorado Springs Airport; the airline had ended passenger service at the airport in November.

Frontier has an agreement with independent fixed-base operator Colorado jetCenter on the airport’s general aviation side of the airfield, where Frontier deplaned one of its three diverted flights, Phillips said.

“We did have one flight where the crew timed out and we had to terminate the flight in Colorado Springs,” said Jennifer de la Cruz, senior director of corporate communications for the Denver-based low-fare carrier. “Those folks were offered a stipend to travel to Denver on their own along with a future flight voucher.”

Flights scheduled to arrive in and depart from Colorado Springs were not impacted by the string of diversions, Phillips said.