Hurricane Sandy Flights Grounded , thousands of flights in the U.S. northeast Monday and upended travel plans across the globe, stranding passengers from Hong Kong to Europe. The massive storm threatens to bring a near halt to air travel for at least two days in a key region for both domestic and international flights.Major carriers such as American Airlines, United and Delta cancelled all flights into and out of three area airports in New York, the nation's busiest airspace. According to the flight-tracking service FlightAware, nearly 7,500 flights had been cancelled for Monday and Tuesday, almost all related to the storm.Delays rippled across the U.S., affecting travellers in cities such as San Francisco to Chicago.