United Airlines has grounded flights nationwide on Wednesday night due to an issue with its weight and balance computer system.

The issue began shortly after 6 pm ET and was fixed within a few hours. However, the impact was widespread. According to FlightAware, more than 1,000 United flights were delayed, and over 40 were canceled as the airline worked to resume normal operations.

Delays continued Thursday for some United Airlines passengers after a technical glitch the day before caused the airline to ground hundreds of flights across the country.