American Airlines, Spirit Airlines cancel hundreds of additional flights as they struggle to recover from disruptions

American Airlines passengers have faced hundreds of cancellations and delays since Sunday, as the carrier struggles to recover from disruptions caused by severe thunderstorms that swept through its Dallas/Fort Worth International hub.

More than 270 flights — or 9% of American’s mainline schedule — had been canceled as of Tuesday morning, according to flight-tracking site FlightAware. At least 120 of the cancellations were due to a lack of flight crew, according to an internal list, which was reviewed by CNBC.

American canceled about 850 flights between Sunday, when thunderstorms struck, and Monday. Close to 2,000 were delayed. About 80 American flights diverted to other airports on Sunday.

Travelers complained on social media about difficulties reaching customer service agents and extensive delays.

“Mother nature isn’t playing nicely and many flights in and out DFW are delayed or cancelled,” American Airlines tweeted to a customer on Sunday.

Ahead of hurricanes and blizzards, airlines will often cancel thousands of flights to avoid passengers and crews getting stranded at airports. Thunderstorms can be more disruptive for passengers and airlines alike because they often lead to rolling delays because they are less predictable.

On top of that, airlines are struggling to staff up to handle a surge in travel demand after urging employees to take buyouts or leaves of absence to cut labor costs in the pandemic last year.

The Transportation Security Administration on Sunday screened 2.24 million people, the most since Feb. 28, 2020.

An American Airlines spokeswoman on Monday said the weather and air traffic constraints caused the delays at DFW.

American had trimmed about 1% of its schedule for the first half of July to handle weather and other disruptions as well as staffing issues.

But the carrier has restored more capacity that some of its competitors like United Airlines and Delta Air Lines.

“And we expect to fly a larger domestic network at DFW this August than we did in August of 2019,” American’s President Robert Isom said on a quarterly call last month.

More capacity leaves little margin for error during disruptions, analysts told CNBC.

Airlines are not required to provide hotel accommodation or food vouchers for travelers whose flights are canceled, according to the Transportation Department.

“Passengers understand that airlines don’t control the weather but the mark of a good airline is how it treats passengers when the chips are down,” said Henry Harteveldt, founder of travel-industry consulting firm Atmosphere Research Group and a former airline executive.

More than 1,100 Southwest Airlines flights, almost a third of the Dallas-based carrier’s schedule, were delayed on Monday, while 44 were canceled. The carrier said the thunderstorms from Sunday sparked the cancellations on Monday.

Spirit Airlines‘ problems continued on Tuesday. It canceled 38% of its schedule or 258 flights, according to FlightAware, on top of about 500 flights between Sunday and Monday.

A spokesman for the low-cost airline on Monday said the disruptions were due to “operational challenges” triggered by weather. Airlines will often cancel flights to get crews in place rather than continue to delay flights.

“We’re working around the clock to get back on track in the wake of some travel disruptions over the weekend due to a series of operational challenges,” the airline said in a statement. “We understand how frustrating it is for our Guests when plans change unexpectedly, and we’re working to find solutions. We ask Guests to actively monitor their emails and flight status before heading to the airport.”