Streamline Air had hoped to bring passenger planes to Portsmouth International Airport at Pease Tradeport as soon as this month, but the plan has been “postponed indefinitely,” according to the airline’s managing director, Mark Cestari.

The plan was postponed from a projected September start because of aircraft unavailability, Cestari said. They expected to acquire another craft but recently found out it would not be available for some time.

Several airlines have come and gone from Pease over the years, and it hasn’t had scheduled air service since Skybus made a brief run in 2008.

Despite the airport’s unstable history, the infrastructure is there and Cestari thinks the market is, too. He said the area is a popular destination for both business and leisure travelers, yet it’s not congested and is easier to reach than other, larger airports in the region.

He said the addition of a Portsmouth service fits their business plan “very well.” But they have not committed to a start date.

“It’s on our list,” he said.

Should they bring service to Pease, he said, the first priority would be regional business destinations, such as the Philadelphia area; Trenton, N.J.; Washington, D.C.; and upstate New York. The New England and Mid-Atlantic region would be served by small, turboprop aircrafts with about 30 seats, Cestari said. The company is also looking into seasonal service to Florida.

Cestari believes Streamline Air’s approach to capturing the niche market would help them succeed. It requires few passengers to break even on flights with smaller planes, avoiding direct competition with larger companies.

“We think we will be successful when others have failed or left,” he said.

For the last five months, the airline has been flying a single route from Bedford, Mass., to Ewing, N.J., offering only public charters. Though the target costumer is the business traveler, about 30 percent have flown for pleasure, Cestari said.