BILLINGS, Mont. (AP) - Essential Air Service flights have resumed at Sidney and Lewistown, about six months after they and four other cities lost EAS service when Big Sky Airlines stopped flying.

Great Lakes Aviation made its first EAS flights from Sidney and Lewistown to Denver on Wednesday.

"We surely feel that the reservations will quickly change, increase, now that you can fly from Sidney to Denver," said Bill Henderson, manager of the Sidney airport. "We hope to pull in customers from Glasgow, Wolf Point, Miles City and Plentywood."

Great Lakes Chief Executive Chuck Howell said Miles City will get air service to Denver next, but a date has not been set.

He said reservations from Sidney and Lewistown has shown switching the hub from Billings to Denver was a good move.

"We are pleasantly pleased with the advanced bookings about 180 days out," Howell said.

Howell says the Cheyenne, Wyo.-based airline plans to restore EAS to Havre, Glasgow, Wolf Point and Plentywood when it can lease "aircraft at favorable terms based on the uncertainty of the EAS program."

Congress hasn't yet reauthorized the EAS program, a Department of Transportation program which spends about $110 million a year to subsidize air service to small towns. Howell estimated the program would need another $90 million to cover higher fuel costs.

Transportation Security Administration officials are doing passenger screenings at Sidney and Lewistown.

Great Lakes took over an $8.2 million EAS contract held by Big Sky Airlines before it ended operations on March 8.