Air travelers experienced delays at some US airports on Monday as staff cuts at control towers took effect, but the widespread havoc and hour-long waits that regulators had predicted last week largely failed to materialize.Instead, the US air system operated as it would if only a few bouts of bad weather had affected schedules.Still, airlines predicted sizable disruption and hundreds of millions of dollars in lost revenue if delays happen as predicted and persist for a year. And travel groups said safety concerns and inconvenience could curb business travel.The Federal Aviation Administration said on Monday that it was grappling with "staffing challenges" at air-traffic control facilities in New York, Dallas-Fort Worth, Los Angeles and Jacksonville, Florida. Controllers were spacing aircraft farther apart for takeoffs and landings, causing delays, the FAA said.