Of the total costs, the impact to passengers in lost productivity and out-of-pocket costs from flight disruptions was $5.3 billion, compared with an average $1.5 billion the last two winters, masFlight said.
"And we're not finished yet," said Tulinda Larsen, economist and masFlight vice president. Monday's storm forced cancellation of 3,285 flights nationwide, according to FlightView, a flight tracking website.
U.S. airports took a $4.5 million hit this winter in lost passenger user charges and passenger spending at concessions. In addition, airports lost $170 million in snow removal and lost aircraft landing fees. That $170 million ultimately will be passed on to airlines through airport rates and charges.
Besides the weather, two new government regulations hurt airlines' "ability to respond," Larsen said.
A tarmac delay rule limits the time an aircraft can spend taxiing, leading carriers to cancel flights rather than be fined as much as $27,500 per traveler. De-icing can take up to 45 minutes, and depending on an aircraft's place in line, airlines may cancel a flight rather than risk a tarmac delay and fines.
In addition, new pilot rest rules Jan. 4 limit the time that airline pilots can be on duty. The rules, in response to the Colgan Air crash near Buffalo, N.Y., in 2009, constrain flexibility to manage flights, causing cancellations, even after an aircraft departs the gate, Larsen said.
Philadelphia International had 483 flight cancellations Monday - about 42 percent of flights. Total weather-related costs were not available "as we are still working this storm," airport spokeswoman Victoria Lupica said.
From Dec. 1 to Feb. 28, about 32 percent of flights were delayed or canceled at Philadelphia International - the 10th-most-impacted U.S. airport - and 9.1 percent of flights were canceled outright, masFlight said.
United Airlines, American Airlines, and US Airways led in systemwide cancellation rates during the period: 7.3 percent, 6.9 percent, and 6.2 percent, respectively.
United was the first carrier last week to warn that the winter weather will hurt first-quarter earnings. United canceled more than 22,500 flights in January and February, with the largest impact on regional flying - nearly four times higher than the same period last year.
Airline analyst Helane Becker of Cowen & Co. said United's network, with hubs in Denver, Chicago, Cleveland, and Newark, N.J., "was hit disproportionately more than other carriers."
Airlines are expected to take another traffic dip this month, with Easter and many spring breaks coming in April, instead of March.