Boeing is offering different base-salary increases to the two groups in its white-collar union, the Society for Professional Engineering Employees in Aerospace (SPEEA).

The company said total compensation for engineers would rise 3 percent each year of the four-year contract. Compensation for technical professionals, those who act as a liaison between the engineers and the mechanics who build the planes, would rise 2 percent each year.

The company Thursday gave details of its initial proposal in a negotiating session at the union's Tukwila headquarters.

Ray Goforth, SPEEA's executive director, said the offer provides the lowest salary increases in 20 years and "appears to be salted with obvious and no-so-obvious take-aways."

He said the union is still analyzing the proposal. "We're trying to figure out what it all means," Goforth said.

The proposal gives about 15,200 engineers a salary hike of 3.5 percent per year for the length of the four-year contract.

Taking into account employee contributions for medical benefits, which will roughly double, the net result is a 3 percent overall compensation increase each year for engineers.

About 7,200 technical professionals (known as techs), who do jobs like programming the machines that mill metal parts, will get a different package.

Boeing's offer would give them salary increases of 3 percent the first year and 2.5 percent in each of the following years.

Again, the increased employee medical-benefit contributions would reduce the overall compensation increase each year to 2 percent, Boeing said.

Boeing had earlier given different raises to the two groups in 2006, as part of the 2005 contract.

The company justified the difference in proposed raises this time by saying that current compensation for the SPEEA techs is "generally much higher above market" than it is for the engineers.

Mike Delaney, Boeing Commercial Airplanes' head of engineering, recently said the company would offer lower compensation increases than in previous SPEEA contracts because Boeing is too far above the average at large aerospace companies.

Goforth said Boeing's market-comparison rationale for the techs is "questionable."

He said techs at Boeing do much more sophisticated work than techs at most other companies that Boeing might use in their market-salary evaluation.

Boeing's offer included pension and medical-plan details that had been revealed earlier.

The basic monthly pension benefit would rise from $83 per year of service to $91 per year of service.

But new hires would get a 401(k) retirement plan instead of the traditional defined benefit plan, a proposal the union has dismissed as a "nonstarter."

The current SPEEA contract expires Oct. 6. And since the union requires two weeks for its mail-in ballot voting process, the two sides have only until the end of next week to come up with a final offer, which the union leadership must decide whether to reject or recommend.

"We hope to have a full analysis available to the members sometime Friday (Sept. 14)," Goforth said of the offer.

Dominic Gates: (206) 464-2963 or dgates@seattletimes.com

This story has been corrected. An earlier version said recent contracts had not contained different salary increases for SPEEA's two employee groups.