Thousands of air travelers faced flight cancellations and delays this weekend as thunderstorms rolled in across the U.S. East Coast and Midwest. In addition to bad weather, a technology failing also contributed to to airline disruptions in the Washington, D.C., area. Nearly 2,000 U.S. flights were canceled on Saturday and Sunday combined, according to flight tracking service FlightAware, and more than 850 U.S. flights had been canceled as of 11:15 a.m. ET Monday. Thousands of additional travelers experienced delays. Staying calm — and knowing your rights — can go a long way if your flight is canceled, experts say.