Thursday is shaping up to be the worst day of a very bad winter for U.S. airlines and their passengers.
More than 5,800 flights were canceled on Thursday alone, as a storm battered the East Coast.
There have been 73,000 U.S. flights canceled so far in 2014 due to a series of winter storms, according to flight tracking service masFlight.
Airline experts say that this year's rash of flight cancellations is the worst to hit the industry since the entire U.S. airspace was completely shut down for four days following the Sept. 11 terrorist attacks.
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