U.S. Air Force plans to expand bomber training activities in the region are being viewed warily by ranchers.

The Air Force is preparing an environmental impact statement to weigh possible consequences of changes in existing air training operations.

The Air Force says the new Powder River Training Complex would allow for more effective use of aircraft and flying hours by providing realistic training closer to home for B-1 and B-52 aircrews from Ellsworth Air Force Base in South Dakota and Minot Air Force Base in North Dakota.

In Wyoming, portions of Crook, Weston, Campbell and Sheridan counties would be included under the preferred option. The area would also encompass large parts of Montana, South Dakota and North Dakota.

The proposed action would restructure and reconfigure existing military operations areas and related air traffic control assigned airspace. It would add new airspace with a floor of 500 feet above ground level and eliminate some existing airspace, according to a notice published in the Federal Register.

Linda DeVine, project manager for the environmental impact statement at Langley Air Force Base in Virginia, said the air-to-air training would be augmented by ground-based emitters.

"Those are basically electronic signals that kind of target the airplane, using those to simulate threats," she said. Aircrews then must counter the perceived threats.

The use of defensive chaff and flares, and supersonic flights 10,000 feet above ground level within the special-use airspace also would be authorized.

DeVine said the number of aircraft flying in the area at one time would not be large, although exact numbers haven't been determined. Periodic exercises also might include fighters and other aircraft.

"It's not going to be 24 hours a day, I can tell you that," she said.

DeVine said the Powder River Training Complex would allow crews to train close to home. Now, only two B1s can be put in the military operations area at one time. Additional crews must train in Nevada or Utah.

Under the plan, a bomber could return to base after a training mission, then be turned around rapidly with a second crew, she said.

But not everyone is persuaded. In a letter, Miles City, Mont., rancher Pat Goggins listed a variety of concerns, including disruption of livestock by airplanes breaking the sound barrier, the potential for fires started by flares and adverse impacts on property values.

"When those jets break the sound barrier they're pretty noisy and disruptive," said Donley Darnell, who ranches south of Newcastle, Wyo. "Basically, it's a taking of private property rights."

"You don't know what you're signing up to live with when you don't have that much experience with it," he added.

Darnell said a rancher can watch the weather and be on guard for possible fires resulting from thunderstorms, and a railroad fire won't be far from the railroad, but flares dropped from an aircraft are different. "These can go anywhere," he said.

Under the full Powder River Training Complex alternative, the Air Force would expand the area overflown at low altitude from about 5,900 square miles to about 31,700 square miles.

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