Southwest Airlines said early Monday that it had fixed technology problems that delayed hundreds of flights on Sunday, and it expects a normal day of operations.
The Dallas company had been warning passengers to arrive at the airport two hours early Monday and print boarding passes beforehand. When asked early whether fliers should continue with those precautions, an airline spokesman said customers should expect a normal day Monday.
Southwest suffered intermittent technical issues on its website, mobile app and in its phone centers and airports check-in systems Sunday. It was using backup systems to check-in travelers lacking printed or mobile boarding passes.
Airline representatives have not said what was causing the problem, but a spokesman has said there was no indication that hackers were involved.
There were about 450 delays out of 3,600 flights scheduled Sunday. Passengers reported long lines at several locations across the country, including major airports like Los Angeles International, which provided water and canopies to those stuck waiting in line outside.
On Monday morning, Baltimore-Washington International Thurgood Marshall Airport tweeted that operations were returning to normal with few delays and diminishing passenger lines.