Delta Air Lines CEO Ed Bastian apologized and offered frequent flyer miles to travelers for lingering flight disruptions on Sunday as the carrier struggled to recover from Friday’s globe-spanning IT outage. The Atlanta-based airline canceled more than 800 mainline flights on Sunday, about 22% of its schedule, according to FlightAware, more than any other U.S. airline. More than 1,600 Delta flights were delayed. The disruptions have persisted at Delta while most other carriers have recovered. American Airlines said it was almost back to normal by Saturday.“I want to apologize to every one of you who have been impacted by these events,” Bastian said in a message to customers. “Delta is in the business of connecting the world, and we understand how difficult it can be when your travels are disrupted.” The airline was offering flight attendants extra pay to pick up shifts, a staff memo on Sunday said. The carrier called some of them on their personal phones to come in, according to a person familiar with the matter. High demand during some one of the busiest periods of summer challenged the airline to find alternative flights for affected travelers, Bastian said in his note. The delays and cancellations are putting Delta in a rare spotlight for the carrier whose leaders pride themselves on reliability and punctuality. United Airlines also had elevated flight disruptions on Sunday with 9% of its schedule canceled, or 260 flights, according to FlightAware. The airline has a number of Microsoft tools that were impacted in the outage, “in particular one of our crew tracking-related tools was affected and unable to effectively process the unprecedented number of changes triggered by the system shutdown,” Bastian said in his note.<br/>