PRESQUE ISLE – Four months after it got them back, Northern Maine Regional Airport will lose the service of the larger 34-seat Saab 340 airplanes.

In October, service will revert to the smaller, 19-passenger Beech 1900s, according to Airport Manager Greg Willard.

On the positive side, Willard said Colgan Air Inc., operating as U.S. Airways Express, will make four daily round-trip flights to Boston with the 1900s, instead of the three with the 340s.

In addition, the planes will be the 1900D series, which offer more comfort and headroom that the 1900C series, which had been used at the airport after last September’s terrorist attacks until May.

Prior to the attacks, Colgan had been serving The County with four flights and Saab 340 aircraft. After the attacks, ridership declined dramatically. The airline responded by reducing flights to three a day and using the smaller planes.

The Saabs were brought back in May because ridership had picked up.

Colgan is the only scheduled air carrier at the airport. It receives a federal government subsidy of about $1.4 million to provide that service under the Essential Air Service program of the U.S. Department of Transportation.

The subsidy acts as an incentive to keep carriers like Colgan providing regular passenger service to small airports in rural areas.

Willard said what is happening at Presque Isle is a reflection of what is happening to the airline industry in general across the country.

He said air ridership is down, and what happens to the larger national airlines trickles down to the smaller regional affiliates like Colgan.

“The country as a whole is not back to pre-September 11 [ridership] levels,” he said. “We’re not back.”

Over the last two months, ridership at Presque Isle has been about 2,000 boardings a month. That compares with 2,300 to 2,400 boardings a month before last year’s attacks.

“Those 300 or 400 people make a whole lot of difference,” he said.

While the decision to go back to the smaller planes is disappointing, Willard said, he was pleased that Colgan was still willing to work with the airport to maintain its market in Aroostook County.

“As long as we can continue to keep our numbers strong, we’ll continue to have an airline to work with us,” he said.

If ridership patterns improve next spring, the larger Saab airplanes could be brought back.

“We’ll just weather the winter like everybody else,” he said.