As Boeing Co. and its biggest union begin contract talks, both sides are expressing optimism that an agreement will be reached before the current contract expires at midnight Sept. 2. Dick Schneider, chief negotiator for the International Assn. of Machinists and Aerospace Workers, which represents about 48,000 of Boeing's 214,000 employees, said that with Boeing slashing at least 20,000 additional jobs by the end of next year, job security is the union's No. 1 priority. However, "the issue of outsourcing--the giveaway of work for the sale of aircraft [in other countries]--is an issue that does not belong at the bargaining table but one that belongs in the halls of Congress," Schneider told reporters. Such outsourcing was one of the chief reasons behind the 69-day strike at Boeing in 1995. Schneider said the union has become convinced that Boeing rival Airbus Industrie of Europe is trying to steal market share by offering huge discounts made possible by government subsidies and that the U.S. government at some point "has to step in . . . to save this giant industry." Boeing's lead negotiator, Vice President Jerry Calhoun, agreed that the two sides have built a strong foundation for the talks; he credited two years of behind-the-scenes meetings. The union formally presented its proposal to Boeing and preliminary negotiations will begin July 6. Around-the-clock sessions are to start Aug. 16. Shares of Seattle-based Boeing rose 56 cents to close at $43.81 on the NYSE.