The impetus for Herb Farmer's Friend Finders International dates back more than 40 years ago, to April 18, 1944. He and fellow crewmen of the 94th Bomb Group were flying their B-17 Flying Fortresses on a raid over Berlin.

"The weather over the continent was really terrible," recalls Farmer. Most of the other bomb groups on the mission had turned back in the face of a seemingly impenetrable weather front. But the skies over the target were clear and, when Farmer's group pulled out of the clouds, they found themselves all alone. Except for the enemy.

"We were bounced by 50 or 60 German Me-109s," says Farmer, now 63, "and they shot down more than half of our group," including his bomber.

Farmer and other members of the crew bailed out and were captured. They ended up spending more than a year in Stalag 17B, a German prisoner-of-war camp.

The men returned home after the war and, for the first few years, they kept in touch through cards, letters and occasional visits. Then Farmer took off for construction work in Alaska. "I went up there in 1951, and stayed for 33 years."

After a few years, Farmer and two of his crewmate/POW pals lost contact with each other. Cards and letters were returned stamped "Addressee Unknown" or "No Longer at This Address."

"I kept thinking that someone should set up some sort of central filing system where people could find each other. The idea cropped up several times, but no one ever did it.

"Finally, I realized I'd have to set up a system like that myself. I was determined to find those guys again, and I wanted other people to be able to do the same thing."

Larry Pedersen, 35, a computer-oriented business consultant also based in Anchorage, shared Farmer's enthusiasm, and together they worked out plans for creation and operation of a "lost and found for friends." Farmer retired from his real-estate investing and he and Pedersen spent the next seven months designing and programming Friend Finders International, which went on-line in October.

The key to its success, they acknowledge, will be volume of entries. Although it requires a sophisticated computer system, the basic idea is simple:

Individuals register, free, with FFI, giving such basic information as name, address, nickname, spouse's first name (if married), when and "where you made those friends you wish to be available to," high school and college attended and graduation dates.

Those searching for friends or relatives provide their own name, address and telephone number, along with the name of the person they wish to find, spouse's name, if married, approximate age and town(s) where they knew the person, as well as other places, if known, that person may have lived.

If the person being sought is registered with FFI, they will send him or her a message to contact the seeker. If the person is not in the FFI system, the computer will search its files weekly for one year, at which time the search order can be renewed.

FFI charges $5 to begin and continue a search. When the individual is found, an additional $5 is charged. Searches for additional individuals cost $2 each when submitted with the initial $5 search request.

Farmer and Pedersen stress that people who register are the first to be contacted when a match is made. "They won't be found if they don't want to be," says Pedersen. "We tell them how to get in touch with the person looking for them; we don't give their address or number to the seeker."

"It will take the cooperation of millions of people to make this work well," concedes Farmer, who says he's committed about $300,000 to the project, "but we are confident we'll have that cooperation."

FFI has made only one match to date, and that one with a little help: A 70-year-old woman in Brooklyn trying to find a friend she lost track of in 1975 was referred to FFI by the Salvation Army. She had attempted unsuccessfully to contact her friend in Florida through a real-estate organization. FFI managed to get word to the subject's son in the Chicago area, where she was visiting. She called FFI, registered, and FFI made the match.

Two other examples of the type of searches Pedersen says have been instituted:

* Two Vietnam veterans who came to Washington for dedication of the Vietnam Veterans' Memorial. They found all the names of buddies who had been killed in Vietnam except that of their old commanding officer, who they heard also had been killed there. Now they think he may be alive and want to find him.

* Danny McKay, 26, of Houston, Tex., who submitted the names of his two brothers and two sisters -- Eddie Lloyd, Tony Joe, Linda Lou and Judy Ann. They were last together in a children's home.

Meanwhile, Farmer himself has a couple of names in the computer. He's still looking for Larry Bouman and William Gilmore, two of his crewmates on that last, ill-fated flight of his B-17, "Little Darling."

Friend Finders International, 314 Lloyd Building, Seattle, Wash. 98101. Call 1-800-FINDERS.