Superstorm Sandy has a long reach, with flight cancelations stranding air travelers around the globe.

The flight-tracking service FlightAware says more than 6,000 flights were canceled today, bringing the total to more than 15,000 canceled across the Northeast over two days. And more than 500 flights scheduled for tomorrow have also been canceled. The number surpasses the winter storm of early 2011 when 14,000 flights to be scrapped over four days.

New York is the nation's busiest airspace with about one-quarter of all U.S. flights going through daily. But the three big New York airports remain closed for a second day.

Flights have been canceled across Europe and Asia and travelers overseas could wait days to get back to the East Coast of the U.S. An official with a trade group for airports worldwide says even if storm damage is minor, it could be a week before operations are normal at major East Coast airports.

Meanwhile in Colorado, 110 flights at Denver International Airport were cancelled today. In Colorado Springs, two flights were affected by the storm.