Airline reservations systems are so complex that one department might cancel a flight even while a reservations worker is trying to shift a traveler onto that same flight, said Joe Brancatelli, a travel expert who runs a newsletter for business travelers.
Travelers don't have any choice but to be patient, he said.
"Where are they gonna go? They hate United today, they go to Delta next week," he said. "Delta screws them, they go to American, and then it's a big circle."