Facing a dwindling number of teen-agers to flip the burgers and fry the chicken, fast-food outlets must dispel myths about using elderly workers, experts on food service and older people said yesterday at a conference examining the problem.

"A lot of companies need to be convinced that it's good business to hire the older worker," said Glenn L. Northup, director of senior employment programs at the American Association of Retired Persons (AARP). "Society for years has dictated that you reach 65 and pfft, you're done, you're over the hill."

Among the myths regarding older workers: They are less alert, and physically and mentally less agile than younger workers. A survey of 140 executives of fast-food and full-service industries attending a two-day "Experience at Work" conference here yesterday concluded that companies who hired older workers were pleased with their performance.

"Employers particularly praise the common sense, the wisdom, the ability to handle a crisis in the older person," said Bernard E. Nash of AARP.

Robert Reid, professor of hotel management at James Madison University, told industry leaders the accident rate for workers over 65 is "virtually half" that for workers in their early 20s.

Recruitment is the biggest problem with workers 55 and older, according to the survey.

Many older workers haven't made job searches or written resumes in years. Also, Social Security rules that penalize seniors who earn more than a set amount deter many from seeking employment, experts said.

Paul A. Mayrand, of the U.S. Labor Department, said many older workers suffer under the outdated delusion that they are not marketable to employers. "They've decided, 'Why should I bother, no one will hire me because of my age,' " he said. "Employers need to be more aggressive to attract them."

According to U.S. Census Bureau figures, the 55-and-older group has grown about 30 percent faster than the total population since 1980. At the same time, the under-25 group shrank by 3 percent. Both trends are related to the post-World War II baby boom.

"A lot of companies have focused on that population bubble from a marketing point of view. What will occur is {that they will now} look ... at that same age segment as a labor pool, not just a customer base," said Bill Fisher, executive vice president of the National Restaurant Association, representing 12,000 companies with 150,000 food outlets.

"The numbers are unavoidable," said Donald E. Doyle, president of Kentucky Fried Chicken, which sponsored the conference with AARP and the restaurant group.

"There's definitely a supply-demand crunch coming," Doyle said, because the fast-food industry relies heavily on these younger workers. "The whole fast-food industry was built on that premise."

However, the same principle might be transferred to the elderly who can work part-time and cope with flexible hours, the experts said.

"In the food-service industry there is a crying need for people." said Fisher. "You've got an elderly segment that wants to work. They want to work on their terms, not yours, but they want to work.