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Why Southwest Airlines could be vulnerable to mass disruptions

Southwest Airlines passengers faced a fourth day of travel woes on Monday as hundreds more flights were canceled.

Southwest Airlines passengers faced more travel woes Monday as hundreds of flights were canceled in a major disruption that began over the weekend and has led to more than 2,000 flight cancellations.

More than 360 flights had been canceled as of Monday afternoon and another nearly 1,000 delayed, according to the flight-tracking site FlightAware. That’s in addition to the more than 1,000 flights canceled on Sunday and another 800 on Saturday.

Southwest said in a post on Twitter Monday that it was working to stabilize operations and anticipates resuming normal service this week. The airline has blamed air traffic control issues and weather in Florida for the disruptions. The airline also batted down suggestions that “employee demonstrations” were a factor.

Experts and aviation consultants said Southwest is particularly susceptible to such a service disruption because of how a cascading effect can occur along its flight network, with one cancellation quickly leading to several.

Henry H. Harteveldt, president and travel industry analyst at The Atmosphere Research Group, told The Associated Press that Southwest operates along what’s known as a “point-to-point route network” and when a delay occurs, the effect makes its way down the remaining stops of the flight. So, a Southwest flight departing Fort Lauderdale, Florida, where the original disruptions on Friday took place, for another major U.S. city may make multiple stops along the route. Harteveldt also told the AP that Southwest has scheduled more flights than it can handle, a problem that started in June.

“What's going on is Southwest scheduled too many flights, they are struggling with pilot recruitment,” Harteveldt told NBC News. “They have a very complicated route network.”

On Monday afternoon, Southwest released a statement saying it extended a "tremendous apology" to its customers and employees over the cancellations. It said that on Friday evening, the airline ended the day with “numerous cancellations, primarily created by weather and other external constraints, which left aircraft and Crews out of pre-planned positions to operate our schedule on Saturday.”

“Unfortunately, the out-of-place aircraft and continued strain on our Crew resources created additional cancellations across our point-to-point network that cascaded throughout the weekend and into Monday,” the carrier said.

The airline said it hoped to restore its full schedule “as soon as possible.”

Airline industry consultant Robert W. Mann said that while such a schedule is not unique to Southwest and might usually suit the carrier, “in the case where a particular flight does not operate for whatever reason, mechanical or weather or crew issues, then obviously the aircraft and the crew are not in the proper place at the end of that flight at that future time.”

“So, it impacts flights down the line and then it becomes a question of, is that a flight into a city where spare aircraft or crew are available such that the subsequent flight could be operated?” he said. “These delays of whatever sort, for whatever reason, do tend to cascade. So, if it's the first flight of the day that doesn’t operate, the rest of the day is now made more difficult.”

This summer, Southwest also faced cancellations and delays due to staffing shortages.

Travel expert Mark Ellwood said airlines have very tight turnarounds for flights during the pandemic, and “one domino goes down, eight flights get canceled and Southwest is really the current example of it.”

Mike Boyd, an aviation consultant at Boyd Group International, said while Southwest’s system can be very efficient, it’s probably also a little more vulnerable to air traffic control issues.

“You screw up Florida, you screw up their whole network a whole lot more because it's connected to the rest of their system. Once it gets screwed up, airplanes are out of place, crews are out of place,” he said. “The crew gets stuck in Omaha and ran out of time, they should be in Orlando. Getting that squared away takes time.”

The airline said Monday that its “schedule looks significantly better than the cancellations we implemented on Saturday and Sunday as we worked on recovery efforts.”