United’s Passengers Were Stuck, but Its C.E.O. Flew on a Private Plane

“I am so frustrated with delays, but even more so with how they treated people at the airport,” she said. “I don’t know if I will use United again.”

Her exasperation was similar to what passengers of Southwest Airlines felt over the winter holidays. Southwest canceled more than 10,000 flights in the four days after Christmas, or about 46 percent of its schedule. On United’s worst day this week, Tuesday, it canceled nearly 800 flights, or about 28 percent of its schedule.

The disruptions have left pilots and flight attendants frustrated, too. Many have had to wait on hold for hours to get reassignments after flights were canceled. Some flight attendants slept at airports, too, according to social media posts.

“Weather last weekend affected everyone, but United is the only airline still struggling to recover, and we know why,” Ken Diaz, president of the United chapter of the Association of Flight Attendants-CWA, which represents more than 25,000 United flight attendants, said in a statement on Thursday. “United management’s failure to properly staff crew schedulers, the flight attendant support team and more has exacerbated these operational issues.”

Mr. Diaz said United had “lost” crews in its system for days because of the breakdown. He also said that the union had warned management last year of problems that could contribute to more disruptions, but that the airline “charged ahead” with an ambitious flight schedule this summer. United used some of the union’s recommendations to get through the current disruption, including making changes to its schedule and agreeing to pay flight attendants three times their normal pay to pick up trips through next Thursday, Mr. Diaz said.

Pilots have expressed similar frustrations.

“It is United Airlines management that is failing our loyal customers by ignoring the warning signs and failing to properly plan,” Capt. Garth Thompson, president of the United chapter of the Air Line Pilots Association union, which represents more than 15,000 of the airline’s pilots, said in a statement.