Airlines predict busy summer; Southwest opens schedule

If you're planning air travel this summer, book soon and prepare for crowds: U.S. airlines expect to see a 4 percent increase in passengers this summer, reaching a record 234 million between June 1 and August 31. The figures are for worldwide travel on U.S. airlines.  In a statement, John Heimlich, vice president and chief economist for trade group Airlines for America, attributed the predicted uptick to "a steadily improving economy, all-time high household net worth and low airfares." &nb