Over 350 Southwest Airlines flights were canceled on Monday after the major delays over the weekend which it said was callused on weather and air traffic control concerns. The company is now being pressed by the pilots union for its alleged failed response which they claim to be a minor task for other aviation companies.

Passengers were left stranded from California to the East Coast due to the flight cancellations, which happened for the third day in a row.

“You can’t really relax when you’re just sitting there waiting for your next flight to be canceled,” a stranded passenger at the San Jose California airport, Vanessa Wheeler, said. Over three days, Wheeler was canceled six times by Southwest. She promised to never book a flight with the airline again as she decided to travel home to Las Vegas through Delta Air Lines.

The FlightAware tracking service said the cancellations on Monday make up 10 percent of Southwest’s schedule. Around 40 percent of the flights or 1, 400 other flights were delayed. Southwest Airlines Co.’s shares have dropped 4.2 percent.

Passengers queue up at the ticketing counter for Southwest Airlines flights in Eppley Airfield Sunday, Oct. 10, 2021, in Omaha, Neb. Southwest Airlines canceled hundreds of flights over the weekend, blaming the woes on air traffic control issues and weather. (AP Photo/David Zalubowski)

The extensive cancellations followed the demand of the Southwest Airlines Pilots Association to the federal court to stop the company’s vaccination order on all its employees. The union, consisting of 9, 000 pilots, said that the airline must talk about the concern as it could entail disability or sick leave if the vaccine triggers a reaction among the pilots.

“We are not anti-vaccination at all, but our pilots are extremely worried about how their medicals are going to be handled” if they cannot fly, according to Casey Murray, union president, who expressed the statement to The Associated Press. He said pilots had not planned a sickout because of the mandate.

The recent disruptions were instead pinned by Murray on the company’s operation. He called it “brittle” and “cracks under the slightest pressure.” Murray shared that Southwest used old-fashioned technology to schedule crew, which leads to falling troubles when flights are called off in one part.