A new $310 million Mauka Concourse underway at Daniel K. Inouye International Airport is designed to increase the number of passengers boarding a plane at the state’s largest airport by about another 1.5 million.

The Mauka Concourse, slated to be completed by December 2020, is just one way that Hawaii’s airport system plans to meet the challenge of continued tourism growth on Oahu, the state’s most visited island, and at islands across the state, according to state Department of Transportation Airports Division Deputy Director Ross Higashi, who spoke Thursday during a Pacific Asia Travel Association Hawaii Chapter luncheon.

With visitor arrivals to Hawaii expected to increase to 10.3 million this year and hit 10.5 million by 2020, Hawaii’s $3.6 billion modernization effort can’t come fast enough, especially the projects that are designed to help state airports comfortably accommodate more flights and passengers. Luckily, Higashi said the effort is at the halfway point, with most of the capital improvements expected to be completed by the end of 2021.

Each year, some 37 million passengers board and exit planes throughout the state’s 15 airports, with approximately 57% of them on Oahu, 21% in Kahului, 10% in Kona, 9% in Lihue, 3% in Hilo and another 1% scattered throughout the rest of the system.

“Twenty million passengers annually enplane and deplane in Honolulu alone,” Higashi said.

Higashi said the Mauka Concourse’s ability to increase Honolulu’s enplaned passengers by 1.5 million annually is based on the possibility of the 250,000-­ square-­foot terminal adding gates for another six wide-body planes or another 11 narrow-body planes. As of Aug. 23, Higa­shi said, the Mauka Concourse project was 47% completed.

Higashi said the state also is trying to grow overall flight capacity statewide by searching for carriers that are willing to operate outside of the 10 a.m.-to- 2 p.m. peak operational period. Higashi said so far the state hasn’t found any takers, but will keep trying because adding more flights means greater economic impact.

For instance, Higashi said the state made $13 million in airport improvements so that A380 service could begin this spring in Honolulu, which has become the 11th city airport in the U.S. that is equipped for the wide-body aircraft. By 2020, Higashi said, All Nippon Airways’ new service is expected to bring an additional $285 million in economic impact to the state and as much as $30 million in tax revenue.