 The TSA expects today to be the busiest travel day ever at U.S. airports. ABC's Alex Stone watching conditions. Under 100 flights have been canceled today. That's actually pretty good for a major getaway day. They're peppered around the country. No one U.S. airport is getting slammed. And many are because of problems in London. Flights that are coming from or heading to London. United has the most canceled flights, and it only has 14 flights canceled. That's less than 1% of United's schedule.