American Airlines Group Inc. canceled hundreds of flights over the weekend due to staffing shortfalls that followed bad weather, snarling weekend travel for thousands of passengers.

American canceled close to 400 flights, or 15% of its mainline operation Saturday afternoon, with more than 250 flights canceled on Sunday, according to FlightAware, a flight-tracking site. Southwest Airlines Co., by comparison, canceled 80 flights Saturday, 2% of its operation, and 20 on Sunday.

The...

American Airlines Group Inc. canceled hundreds of flights over the weekend due to staffing shortfalls that followed bad weather, snarling weekend travel for thousands of passengers.

American canceled close to 400 flights, or 15% of its mainline operation Saturday afternoon, with more than 250 flights canceled on Sunday, according to FlightAware, a flight-tracking site. Southwest Airlines Co. , by comparison, canceled 80 flights Saturday, 2% of its operation, and 20 on Sunday.

The majority of American’s cancellations Saturday were due to a lack of available crew members, especially flight attendants, according to internal airline figures viewed by The Wall Street Journal.

Several U.S. airlines have had difficulty managing as travel quickly returned  from hibernation during the Covid-19 pandemic. Southwest earlier this month attributed its own operational meltdown to a lack of staffing cushion that left it unable to recover for several days after bad weather in Florida knocked its entire operation off course.

Earlier

Southwest canceled some 1,900 flights in the span of 48 hours, leading to huge lines across airports. But just what led to one of the U.S.’s top airlines having to cancel so many flights, and what could that tell us about the aviation sector’s recovery? WSJ’s George Downs looks into how Southwest got here, and whether or not it's likely to happen to other airlines during the holidays. Illustration: George Downs The Wall Street Journal Interactive Edition

American had struggled with similar challenges over the summer but had said it managed to right itself, in part by scaling back its schedule. The airline has said last month was its best September ever by metrics like on-time performance and cancellations.

David Seymour, American’s chief operating officer, told employees in a memo Saturday that the troubles began with severe wind gusts that cut arrival capacity by more than half at the airline’s Dallas hub at the end of the week.

“These few days to close out October will be challenging,” he wrote.  “With additional weather throughout the system, our staffing begins to run tight as crew members end up out of their regular flight sequences,” he wrote.

American has been proactively scrapping flights to avoid last-minute cancellations, and most customers have been rebooked on the same day, he wrote.

Airline staffing challenges often become more acute at the end of a month, when on-call crew members bump up against limits on the number of hours they can work.

American flight attendants have complained for months about challenges such as last-minute schedule changes and difficulty finding hotels and transportation, particularly when bad weather upends operations. Paul Hartshorn Jr., a spokesman for the union that represents American’s flight attendants, said Saturday that staffing remains strained.

Mr. Seymour said in the memo American is adding more staff in preparation for the busy holiday season, with nearly 1,800 flight attendants returning from long-term leave and 600 newly hired flight attendants joining by the end of December. American is also boosting staff at airports and its reservations and maintenance teams, he wrote.

Write to Alison Sider at alison.sider@wsj.com

Corrections & Amplifications
American will have 600 newly hired flight attendants by the end of December. An earlier version of this article incorrectly said by the end of September. (Corrected on Oct. 30)