Casper/Natrona County International Airport will lose some passenger service to Salt Lake City and gain seats to Denver in a September flight schedule reshuffling.

On Sept. 2, SkyWest/Delta flights between Denver and Salt Lake City will be reduced from three to two, with the loss of one regional jet and 50 seats in capacity airport manager Glenn Januska said.

On Sept. 3, SkyWest/United service between Casper and Denver will increase to five daily flights, but will lose a regional jet. There will be a net gain of 24 seats on the route.

Januska said the changes in part may reflect seasonality in the Casper market and a desire to economize in the face of high fuel costs.

In the past, when fuel prices were lower, airlines may have opted to remain in a market year-round for the sake of consistency, even though there may have been more empty seats in winter than what a carrier liked.

"Now all of a sudden, when the fuel prices are up, what may have been kind of marginal to keep an aircraft in the wintertime may now be, 'Hey, we need to pull that out,'" he said.

Next summer, if business picks up and fuel costs moderate, perhaps the lost Salt Lake City service will be restored, he said. "Hopefully, this is not a permanent thing."

While the changes are in the schedule, it's a long way to September, Januska said. "You never know what's going to happen with the airlines."

In May, SkyWest, Inc. reported a 2.9 percent decrease in available seat miles, while revenue passenger miles decreased by 5 percent, when compared to May 2007.

The figures reflects combined traffic of St. George, Utah-based SkyWest Airlines and Atlanta-based Atlantic Southwest Airlines. Both are wholly owned subsidiaries of SkyWest.

Business Editor Tom Mast can be reached at tom.mast@trib.com, or call 307-266-0574.