Federal officials predict that the number of passengers traveling on U.S. airlines should increase 3.5 percent this year.

They also expect U.S. airlines will carry 1 billion passengers a year by 2021, two years faster than previously forecast.

The Federal Aviation Administration released its annual travel forecast on Tuesday, a report that covers the next 20 years.

The agency says the growth in travel will increase the need for changes including a new satellite-based air traffic control system to replace the current radar-based technology.

The FAA expects international traffic to grow more rapidly than domestic travel — with U.S. airlines handling 7.8 percent more international passengers but only 3 percent more domestic passengers this year. The FAA says that trend should continue through 2031 due to faster economic growth in other parts of the world.

That's in line with other forecasts. On Monday, the International Air Transport Association, which represents major global airlines, predicted 3.3 billion air travelers worldwide by 2014, up nearly one-third from 2009, with China being the major driver of growth.

The FAA predicts that passengers on major U.S. airlines will pay 2 percent higher fares on domestic flights and 5 percent more for international trips this year than last year. The FAA says, however, that rates will drop slightly over the long haul.