The relentless snow and ice storms this winter have led to the highest number of flight cancellations in more than 25 years.

U.S. airlines have canceled more than 75,000 domestic flights since Dec. 1, including more than 14,000 this week. That’s 5.5 percent of the 1.37 million flights scheduled during that period, according calculations based on information provided by flight tracking site FlightAware.

It’s the highest total number and highest percent of cancellations since at least the winter of 1987-1988, when the Department of Transportation first started collecting cancellation data.

The nation’s air traffic system was still recovering Friday from the latest bout of bad weather. Flights were taking off again, but thousands of passengers weren’t.

“This year is off to a brutal start for airlines and travelers,” FlightAware CEO Daniel Baker said. “Not only is each storm causing tens of thousands of cancellations, but there’s been a lot of (storms).”

And February still has two weeks left.

Mother Nature isn’t entirely to blame. A mix of cost-cutting measures and new government regulations has made airlines more likely to cancel flights and leave fliers scrambling to get to their destination.

There were days this week where more than 70 percent of flights were canceled in Baltimore, Philadelphia, Washington D.C. and Charlotte, N.C. Even typically warm — or at least warmer — weather cities were not immune. The world’s busiest airport, Hartsfield-Jackson Atlanta International Airport, was paralyzed Wednesday by ice and snow.

Making things worse for travelers this winter, airlines have been cutting unprofitable flights and packing more passengers into planes. That has been great for their bottom line but has created a nightmare for passengers whose flights are canceled due to a storm. Other planes are too full to easily accommodate the stranded travelers. Many must wait days to secure a seat on another flight.

Carol Cummings, 23, was trying to fly Thursday on United Airlines from the Washington D.C. area to Los Angeles to visit a high school friend for the long Presidents Day weekend. The flight was canceled, and Cummings was automatically rebooked for a flight Monday — the day she was supposed to return home. After 2 1/2 hours on hold, United offered to move the trip to another weekend — for an extra $150 — or to refund her ticket.

“I am annoyed and surprised at the lack of customer concern I experienced,” she says.” Cummings is waiting for her refund.

This winter is even more painful than 2000-2001, when 66,000 — or 4.2 percent of December, January and February scheduled flights — were scrapped.

“As an industry you are prepared for bad weather, but I’m not sure if you are ready for this many events back to back,” says Savanthi Syth, an airline analyst with Raymond James.

Passengers weren’t prepared either.

“It’s extremely exhausting. I feel like a walking zombie,” says Colleen Hoover, 52, who arrived at Miami International Airport at 9 a.m. Wednesday. She was originally scheduled to fly from St. Croix in the Virgin Islands to Philadelphia, but her flight was re-routed to Puerto Rico and eventually Miami.

She says she slept at the airport hoping to catch another flight back home. “I’m running on empty, or adrenaline.”

Airlines are quicker to cancel flights these days, sometimes a day in advance of a storm. It’s rarer to see planes parked at the edge of runways for hours, hoping for a break in the weather, or passengers sleeping on airport cots and cobbling together meals from vending machines. The shift in strategy came in response to new government regulations, improvements to overall operations and because canceling quickly reduces expenses.

In May 2010, a new DOT rule took effect prohibiting airlines from keeping passengers on the tarmac for three hours or more. So, airlines now choose to cancel blocks of flights to avoid potential fines of up to $27,500 per passenger or $4.1 million for a typical plane holding 150 fliers.

Additionally, the government implemented a new rule at the start of January, increasing the amount of rest pilots need. That’s made it harder to operate an irregular schedule, such as those seen after a storm. In order to have enough well-rested pilots, airlines cancel more flights.

Not all of the cancellations are tied to regulations. Airlines have learned in recent years that while a large number of early cancellations might cause short-term pain, it helps them better reset after the weather clears.

Keeping planes at airports outside of the storm’s path can protect equipment and thereby get flight schedules back to normal quickly after a storm passes and airports reopen. It also allows airlines to let gate agents, baggage handlers and flight crews stay home.