NEW YORK (AP) — It was a tough start to the week for many air travelers. Flight delays piled up all along the East Coast Monday as thousands of air traffic controllers were forced to take an unpaid day off because of federal budget cuts.

Some flights into New York, Baltimore and Washington were delayed by more than two hours as the Federal Aviation Administration kept planes on the ground because there weren't enough controllers to monitor busy air corridors.

One out of every five flights at New York's LaGuardia International scheduled to take off before noon on Monday was delayed 15 minutes or more, according to flight tracking service FlightAware. Last Monday morning, just 2 percent of LaGuardia's flights were delayed. The situation was similar at Washington's Reagan National Airport, in Newark, N.J. and in Philadelphia.

Some flights were late by two hours or more.

For instance, the 8 a.m. US Airways shuttle from Washington to New York pushed back from the gate six minutes early but didn't take off until 9:58 a.m. The plane landed at 10:48 a.m. — more than two and a half hours late.

If travelers instead took Amtrak's 8 a.m. Acela Express train from Washington, they arrived in New York at 10:42 a.m. — 4 minutes early.

The furloughs are part of mandatory budget cuts that kicked in on March 1 after Democrats and Republicans missed a deadline to agree on a long-term deficit reduction plan.

FAA officials have said they have no choice but to furlough all 47,000 agency employees, including nearly 15,000 air traffic controllers. Each employee will lose one day of work every other week. The FAA has said that planes will have to take off and land less frequently, so as not to overload the remaining controllers on duty.

Critics have said the FAA could reduce its budget in other spots that wouldn't delay travelers.

Monday is typically one of the busiest days at airports with many business travelers setting out for a week on the road. The FAA's controller cuts — a 10 percent reduction of its staff — went into effect Sunday but the full force wasn't felt until Monday morning.

Some travel groups have warned that the disruptions could hurt the economy.

"If these disruptions unfold as predicted, business travelers will stay home, severely impacting not only the travel industry but the economy overall," the Global Business Travel Association warned the head of the FAA, Michael P. Huerta, in a letter Friday.

Deborah Seymour was one of the first fliers to face the headaches.

She was supposed to fly from Los Angles to Tucson, Ariz., Sunday night. First her 9:55 p.m. flight was delayed four hours. Then at 2 a.m., Southwest Airlines canceled it.

"It's pretty discouraging that Congress can't get it together and now it's reached the point that we can't get on an airplane and fly," Seymour said.

One thing working in fliers' favor Monday was relatively good weather at most of the country's major airports. A few wind gusts in New York added to some delays, but generally there were clear skies and no major storms.

Delta Air Lines said it was "disappointed" in the furloughs and warned travelers Monday to expect delays in the following cities: New York, Philadelphia, Fort Lauderdale, Fla., Chicago, San Francisco, Los Angeles and San Diego.

Many flights heading to Florida were seeing delays of up to an hour.

Raymond Adams, president of the air traffic controllers union at New Jersey's Newark airport, said on Twitter than a few flights out of Newark to the south got sent back to Newark because the Washington area air traffic control system was overwhelmed.

The FAA has also furloughed other critical employees including airline and airport safety inspectors.

The country's airlines and some lawmakers have suggested the White House is causing misery for fliers to put pressure on Republicans in Congress to rescind the cuts. They say the FAA is ignoring other ways to cut its $16 billion budget. Two airline trade associations and the nation's largest pilots union filed a lawsuit Friday asking the U.S. Court of Appeals to halt the furloughs. No hearing date has been set.

In a letter to the FAA Friday, Delta's general counsel Ben Hirst asked the agency to reconsider the furloughs, saying it could make the cuts elsewhere and could transfer funds from "non-safety activities" to support the FAA's "core mission of efficiently managing the nation's airspace."