Book your flights for Thanksgiving dinner now, and expect your plane to be packed with other travelers, flight-related groups advised Thursday. A Hotwire survey released Wednesday found 78 percent of people who expected to travel during Thanksgiving week had not yet booked their flights, hotels or cars. About 24 million people are expected to fly during the holiday period, up by 150,000 passengers from last year, said industry trade group Airlines for America. However, fewer planes will be flying because airlines have grounded some to cut expenses. Consequently, cabins could be 90 percent full on the busiest travel days, Wednesday, No. 21, Sunday, Nov. 25 and Monday, Nov. 26, Airlines for America said. Flyers also might check flights at smaller airports for cheaper tickets, CNN reported.