WICHITA, Kan. (AP) -- The Boeing Co.'s decision Wednesday to lay off 800 workers at its Wichita defense plant sent shudders through this aviation community, marking the third major layoff in a month at one of the city's aircraft manufacturers.

While Boeing blamed the layoffs at its Integrated Defense Systems facility in Wichita on the delay of a U.S. Air Force tanker replacement program and the end of other work projects, the cuts come at a time when local business jet manufacturers are already struggling with the global financial credit crisis.

Hawker Beechcraft announced earlier this month it plans to lay off nearly 500 people, with Cessna just days later also saying it was laying off 500 workers in Wichita.

The city's aviation sector has also been affected by the recently settled Machinists union strike against Boeing. Most of the 10,500 employees at Spirit Aerosystems -- a major Boeing supplier of aircraft parts -- are still working three-day weeks as Boeing gradually resumes commercial airplane production.

The layoffs announced Wednesday amount to 27 percent of the work force at Boeing's Wichita IDS plant.

"It is one more impact to the economy here in Wichita and the surrounding communities," said Bob Brewer, Midwest director for the Society of Professional Engineering Employees in Aerospace.

The cuts also come amid contract negotiations for the more than 700 Boeing engineers represented by the Wichita unit of the Society of Professional Engineering Employees in Aerospace. The announcement adds greater urgency to contract language that would have dealt with voluntary layoffs for workers who wanted to retire or move on from the company.

"It certainly puts a different aspect on negotiations," Brewer said. "We are still trying to adjust to what was announced today."

Brewer said the layoffs were not unexpected, given that there has not been much military work coming into Boeing's Wichita IDS facility since the company got rid of its commercial aircraft operation in the city in 2005.

"The numbers were much higher than we anticipated, but the action itself we thought that was coming," Brewer said.

Chicago-based Boeing, which makes military aircraft, civilian jetliners and surveillance systems, said Wednesday the reduction at the IDS facility will affect managers as well as salaried and hourly workers.

Kansas Sen. Sam Brownback, a Republican, said he would continue to push for Boeing to secure a military contract for the new airborne tanker "that keeps jobs in America and takes advantage of the expertise we have in Kansas."

"The best way to preserve and grow jobs in Wichita is to win the tanker contract," Brownback said.

Had Boeing won the tanker bid earlier this year, the contract would have brought between 300 and 500 direct Boeing jobs. But its impact in Kansas could have been as high as 3,800 jobs when suppliers such as Spirit Aerosystems and others were considered. The tanker's economic impact for Wichita had been estimated at $145 million.

"Boeing Wichita is at a crossroads," Brewer said. "I think you have to figure out what you want the future of Wichita to look like."