In two days of talks, Boeing rejected proposals from both SPEEA and Barnes, having said going into the mediation that it would be making no new proposals of its own.

The work stoppage was expected to disrupt airplane production in the Puget Sound area, especially in the first few days, when participation was expected to be the strongest.

More than 99 percent of SPEEA voting members said "no'' to Boeing's first proposal in December.

By a narrower margin, the union rejected a revised proposal last week that SPEEA negotiators had approved and which offered slightly better pay and bonus prospects and eliminated a controversial 10 percent premium for medical care.

Boeing had been preparing for a strike, although it was not clear how many SPEEA members would walk out, since only about 13,750 pay dues.

"The company is clearly disappointed that we were not able to reach a solution. We will be facing a strike by several thousand employees,'' said Boeing labor spokesman Peter Conte.

"Our focus now is on maintaining operations to the highest degree possible,'' Conte added.

SPEEA spokesman Bill Dugovich said the union was expecting "nearly full participation" at a union rally called for Wednesday in nearby Renton, Washington.

Boeing on Monday rescinded its latest contract offer to SPEEA as its members marched or walked information pickets at Boeing facilities.

SPEEA said some Boeing managers had asked key SPEEA members -- designated engineering representatives (DER) -- to show them how to do their jobs.

DERs are authorized by the Federal Aviation Administration to approve and certify changes made to engineering design during production. Their absence could slash airplane output, unless they were replaced.

Conte said he had no knowledge of any attempt to train managers to perform DER tasks.

Boeing Chief Executive Phil Condit, a one-time Boeing engineer, took no direct role in the talks, but had approved the company's strategy, Conte said.

Condit brokered a last-minute deal with the 44,000-strong Boeing machinists' union last August, although no one was expecting a repeat performance.

SPEEA, which has been without a contract since December, has never struck beyond a one-day walkout during contract talks in 1993.

The more aggressive machinists have hurt Boeing badly in the past, disrupting production during a 69-day walkout in 1995.

SPEEA negotiator Stan Sorscher said Boeing's drive to boost profits by cutting costs and slashing spending on research and development had embittered many employees.

"Talented young employees are leaving. Career planning for talented experienced employees centers on early retirement. Productivity…in the workplace has reached lows unimaginable two years ago," Sorscher wrote in an e-mail.

Boeing has struggled to boost its bottom line after losing $498 million in 1997 -- its first loss in 50 years. It earned $1.2 billion in 1999.