US airline-passenger numbers will reach 1 billion in fiscal 2021, two years sooner than projected, because of improved economic growth, the Federal Aviation Administration said in its annual forecast.

Passenger ranks, which totaled about 713 million in the year ended in September, will increase at an average annual rate of 2.8 percent over the next two decades, the FAA said today. The FAA, which oversees all US civil aviation, conducts the annual forecast for long-term staffing and equipment planning.

“Only a modernized air transportation system will be able to keep up with our forecasted demand,” FAA Administrator Randy Babbitt said in a statement. The FAA has begun an effort dubbed NextGen to overhaul its ground-based radar system to one that will rely upon satellites.

The revision marks the first time in more than a decade the agency moved forward the point at which it predicts 1 billion passengers. The FAA cited forecasts for an average 2.7 percent increase in US gross domestic product over 21 years. The FAA last year estimated GDP growth of 2.6 percent from 2014 to 2030.

Domestic enplanements, or the number of passengers that board flights within the US, will rise 3 percent this year and then 2.5 percent annually over the next 20 years, the FAA said. International enplanements will increase 7.8 percent this year and average 4.3 percent for the remaining forecast period.

Takeoffs and landings will fall 0.6 percent in the current fiscal year, and then grow at an annual rate of 1.6 percent in the following 20 years, the FAA projects.

The FAA in 2000 and 2001 predicted the US network would top 1 billion passengers by 2010. In 2002, the FAA slid that expected date back to 2013. The FAA in following years moved it back again – first to 2015, then to 2016, then to 2021, and finally, last year, to 2023.