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.

(Hat tip to Adam Simpson)