Frigid Weather Cripples Air Travel System

The chaos in the nation's air travel system worsened on Monday as freezing temperatures, snow and ice blanketed much of the country, causing airlines to cancel thousands of flights and stranding passengers from Fort Lauderdale, Fla., to Los Angeles.

The biggest impact was in the Northeast and the Midwest, where polar weather swooped in. Airlines canceled 4,400 flights on Monday, bringing the total to more than 17,000 over the last week, according to FlightStats.com, a flight information website. The delays, during one of the busiest travel periods of the year, marooned thousands of people trying to return home from holiday trips, begin a new school term, or get back to work. Fans of Florida State and Auburn scrambled to find their way to Pasadena, Calif., for college football's national championship game at the Rose Bowl on Monday night.

The disruptions came as new federal regulations giving more rest time for airline pilots began on Jan. 1. While crippling weather was the main cause of the delays, at least one airline, JetBlue Airways, cited the new rules for making a bad situation even worse.

The airline said on Monday that it had suspended all flights in and out of Boston and the three main New York-area airports for 17 hours in anticipation of the latest cold wave in order to get its crew and planes in position for a fresh start on Tuesday.

The delays are expected to continue for days, since airlines now operate on a much tighter schedule, leaving them with little slack, and few spare planes, to rebook passengers on future flights.

One traveler, Courtney Morrissey, said she was supposed to start a new job on Monday in Denver but has been stuck in Rochester since last Thursday after three different flights she had rebooked were canceled. She is now scheduled to fly on Wednesday.

'I am not holding my breath,' Ms. Morrissey said. 'Every time they put me on a new flight now, I expect that to be canceled.'

Widespread cancellations are increasingly common. In 2012, Hurricane Sandy forced airlines to cancel more than 20,000 flights over a four-day period, mostly in the Northeast. But with the hub-and-spoke nature of the modern airline business, and the growing consolidation of the industry, the ripple effects of these touch every corner of the country.

JetBlue stopped all service from 5 p.m. Monday to 10 a.m. Tuesday from Logan Airport in Boston and from Kennedy International, La Guardia and Newark Liberty International Airport in the New York area. The airline warned of the effect of new Federal Aviation Administration regulations that require pilots to be given more rest time before and after flights. It also limits the number of hours they report for duty.

'In the midst of us repairing those schedules disrupted by this week's winter storms, we're facing an additional challenge as new F.A.A. rules went into effect for crew rest,' JetBlue said in a statement. 'These rules further impact our ability to operate an already disrupted schedule, causing our pilots to 'time out' even sooner. As a result, additional cancellations are likely to occur as we work to reset the operation.'

Captain Sean Cassidy, a vice president at the Association of Air Line Pilots, said it was too soon to know what impact, if any, the new rules had on the recent cancellations. Airlines have had nearly two years to review their schedules and operations and plan for the new regulations.

'It's rather unfortunate that the day the new rule change became mandatory happens to coincide with this massive weather system,' Mr. Cassidy said. 'It is very difficult to extrapolate.'