By any measure, the Greater Washington Board of Trade's annual meeting last Thursday can be called a success. This year's event, which attracted a sellout of more than 800 persons, appeared to live up to expectations as the biggest -- if not the most prestigious -- local business luncheon of the year.

As always, the annual meeting affords an opportunity to shake hands, backslap and embrace -- rituals that often lead to lucrative business deals or further "networking," as they call it in business and professional circles. Against a backdrop of balloons, martial music, a military honor guard and a stirring rendition of the National Anthem, it is doubtful that many deals were sealed over lunch.

Those who attended came away apparently satisfied in the end, however, with the highlight of the event -- an upbeat keynote speech on the U.S. economy by one of the nation's captains of industry, Thomas G. Pownall, chairman of Martin Marietta Corp.

Indeed, it was Pownall's tough, no-nonsense defense of the American economic system that made the biggest hit at this year's annual meeting, judging from the comments of many of those who attended. Pownall's assertion that he doesn't envision "this highly talented and educated nation, bursting with energy, and confident of its soaring capabilities, sinking into decline" struck a responsive chord.

An equally strong declaration from the dais by outgoing Board of Trade President John T. (Til) Hazel is likely to have a more profound impact on the local business community in the long run, though initial reaction seemed anything but enthusiastic. Perhaps it was the blunt assertion in Hazel's brief valediction that shocked many in the audience. They were totally unprepared, perhaps, for Hazel's challenge to the business community to work to resolve the pervasive unemployment problem that threatens to erode the city's economy.

"By any standard, it is "intolerable" for a quarter of the work force in the District to be unemployed "while we in the suburbs are enjoying high employment," Hazel declared.

Hazel didn't identify the source of his statistics, but usually reliable sources say a soon-to-be-released study paints a bleak picture of unemployment in the District.

After soaring above 12.5 percent last year, unemployment in the District has tapered off to 8.6 percent, a level that is described as stable by the D.C. Department of Employment Services. But the department's most recent labor summary shows the gap widening between job growth in the District and in the suburbs. The private sector in Washington's suburbs accounted for 95 percent of the 48,000 new jobs added to the local economy in a 12-month period that ended in September.

Nothing tends to indicate that the trend will be reversed any time soon. If anything, job growth in suburban jurisdictions will increase as the demand rises for more professional and technical workers to fill high-technology and service jobs in suburban office parks and other employment centers. D.C. Department of Employment Services projections show that professional and technical workers will likely replace clerical workers as the area's largest occupational group by the end of the decade.

In the meantime, it should be obvious by now that pervasive unemployment in the District can't be attributed entirely to a decline in federal employment. Over the past year, in fact, federal employment has improved in the District. A loss of 1,900 D.C. government jobs between September 1983 and September 1984 was offset by an increase of 2,600 jobs in the federal sector.

Hazel stopped short of recommending a specific course of action that business might take in addressing unemployment in the city. However, he has set the tone for serious dialogue within the business community and between business and the D.C. government. For whatever it's worth, attention is invited to a column I wrote almost a year ago when the District's unemployment problem seemed serious enough to warrant drastic action by business and government.

The same recommendation seems as applicable now as it did then: The mayor and Washington's business leaders should seriously consider convening a summit on the unemployment problem.

Solutions aren't likely to be found quickly, even with the existence of vehicles such as the Targeted Jobs Tax Credit Program. But a commitment to a partnership seems worth the effort by business and government, if only for the sake of preserving the integrity of the core of the region's economy.

Hazel's concern and his prodding of colleagues may finally cause decision-makers to give more than lip-service to the problem.