American Airlines has had to cancel hundreds of flights this weekend due to staffing shortages triggered by weather-related disruptions, according to FlightAware data on Saturday.

The website, which tracks delays and cancellations in the US skies, showed that American Airlines cancelled more than 800 flights on Friday and Saturday and expects more than 400 cancellations on Sunday.

American Airlines CEO David Seymour said in a memo to staff on Saturday that the difficulties began on Thursday with strong wind storms that blocked capacity at the company’s Dallas hub and delayed staff positioning for upcoming flights.

The company boss said that with additional weather issues, staffing “begins to run tight as crew members end up out of their regular flight sequences.”

He said he hoped that operations will be restored “quickly with the start of a new month.”

He also announced the return of 1,800 flight staff who have been on standby since the pandemic and the hiring of another 600 by the end of December, as well as 4,000 airport employees.

Most travellers affected by the cancellations were able to rebook for the same day, said the airline, which operates 6,700 daily flights worldwide to 350 destinations in 50 countries.

American Airlines is not the first airline to suffer a staffing shortage as travel demand picks up with vaccinations and the lifting of restrictions.

Last week Southwest had to cancel more than 2,000 flights, costing it $75 million.

The problems were triggered on a Friday afternoon by bad weather and a temporary lack of air traffic controllers in one area of Florida. But the situation was quickly exacerbated by limited staffing levels and then snowballed over several days.