Delta cancelled several thousand flights between Wednesday and Sunday. They cancelled flights at a rate 3 to 7 times as high as other airlines across those days, and fewer than a third of their flights operated on time Thursday and Friday.
Atlanta got a storm to start things off, and even flights out of other hubs were affected because of aircraft cycling through Atlanta. New York and Detroit saw a storm on Thursday. But the airline didn’t come close to recovering on Friday or even through the weekend.