Updated with additional flight cancellation numbers.CHARLOTTE, N.C. -- ( TheStreet) -- Airlines have cancelled more than 11,000 flights throughout the Northeast as Hurricane Sandy approaches. As of Monday morning, major airlines have ceased operations in Baltimore, New York, Philadelphia and Washington, due primarily to high winds and the inability of employees to get to work due to the shutdown of mass transit systems throughout the region. Several carriers said they expect to begin resuming service to those airports sometime Tuesday. In recent years, airlines have altered the model for responding to storms, preferring to cancel flights early so that passengers can plan better and aircraft will be in the right place to resume service when the storm ends. In the past, the idea that "we can fly through this" was more prevalent. United ( UAL) moved particularly quickly to deal with Sandy. Around midday Sunday, the carrier said it had cancelled 3,700 flights, or 16% of its schedule from Sunday into Wednesday. Meanwhile, Delta ( DAL) has cancelled about 2,100 flights Sunday through Tuesday morning. American ( AAMRQ.PK) has cancelled 1,571 and US Airways ( LCC) has cancelled 1,600. Southwest ( LUV) has cancelled 599, with an additional 188 AirTran cancellations. JetBlue ( JBLU) said it cancelled more than 1,000. On Monday morning, US Airways got its originating flights off from airports in Boston, Hartford, Conn., and Providence, R.I., before ceasing operations at the three airports for the rest of the day. In Baltimore, New York, Philadelphia and Washington, US Airways ceased operations on Sunday. However, the carrier expects to begin flying in all four cities on Tuesday, "pending the movement of the storm, field conditions, and any damage to airports/facilities," said spokeswoman Michelle Mohr. FlightAware.com said "a big factor potentially affecting the re-opening coastal airports is high tide." It said New York LaGuardia is the most likely big airport to be affected, since it is only 4 feet above the high tide, followed by New York Kennedy. Both airports said they were open on Monday morning, although most carriers had ceased service. United spokesman Rahsaan Johnson said Sunday: "Our operations team has been working since Friday on scenarios that would accommodate customers flying to and from the East Coast this weekend, while also moving our airplanes out of Sandy's way to avoid having them stuck in airports in Sandy's path."