Cancelations by Southwest Airlines over the weekend came close to 2000 over the weekend and crossed this number on Monday. The airlines reported that the delays were due to “weather challenges” as well as “unexpected air traffic control issues” in Florida. However, other airlines faced very few disruptions in the same period and the Federal Aviation Administration (FAA) said that the air traffic control staffing shortage occurred “for a few hours Friday afternoon.”

In a Friday court filing, the union called a vaccine mandate by Southwest Airlines unlawful and said that it imposed “new conditions of employment” on pilots. It requested a judge to prevent the airline from enforcing that requirement as well as other polices and actions.

Many Republicans comments about vaccine mandates as the cause of the disruptions was due to the timing of the disruptions. Some of them included Tucker Carlson, Ted Cruz and Donald Trump Jr.

However, on Saturday, the Southwest’s pilot union said that their pilots were “not participating in any official or unofficial job actions.”

On Monday, Southwest released another statement which said that they had several cancelations due to weather and external constraints. They said that these issues resulted in aircrafts and crews not being in pre-planned positions which in turn affected their operations on Saturday.

Last week, the union had raised objections about Southwest airlines vaccine mandate policy. The pilots’ union said that it was not against vaccinations. However, it also cautioned that there could be labor shortages and flight disruptions if the mandate was enforced.

Other airlines including United Airlines, American Airlines, Alaska Airlines and JetBlue Airlines have also put forth vaccine mandates but have not suffered from major disruptions or huge shortage of staff. Delta Air Lines has not mandated vaccinations but unvaccinated employees pay an additional $200 per month for health insurance. Southwest, which is headquartered in Dallas, Texas, was one of the last few airlines to mandate vaccines by early December.

Late Sunday, Southwest Airlines Pilot Association (SWAPA) president Casey Murray released a statement said that there were “false claims” of job actions by their pilots on “social media” and that there were no “work slowdowns or sickouts” that were “related to the recent mandatory vaccine mandate or otherwise.”