 Delta and United topped the cancellations. Delta Chief Executive Ed Bastian said in a message to customers Sunday that flight cancellations continued as the airline tried to recover its systems and restore operations. He noted that the pause in Delta's operations resulted in more than 3,500 Delta and Delta Connection scrub flights. Delta's been offering waivers to affected customers. Transportation Secretary Pete Buttigieg spoke to Bastian on Sunday about the airline's high number of cancellations since Friday.