LOS ANGELES, AUG. 7 -- Brian Willson remembers nothing of the screeching, breathless moment three years ago when a Navy munitions train rolled over him as he tried to demonstrate against American involvement in Central America. His stunned mind even today refuses to recall anything that happened from the moment his small band of protesters sat down outside the U.S. Naval Weapons Station in Concord, Calif., to the moment six days later when he found himself in a hospital with both legs gone below the knee.

Nonetheless, the incident has been studied exhaustively by federal agencies and teams of lawyers, who have found Willson's case persuasive enough that the government has tentatively agreed to pay him and four other demonstrators $920,000 to settle it.

Thomas Steel, an attorney for Willson and the other plaintiffs, said today that the settlement of their suit against the Navy and five of its civilian employees has been approved by federal attorneys in San Francisco but still needs the formal endorsement of the U.S. Justice Department in Washington.

William McGivern, the U.S. attorney in San Francisco, said he could not comment because of a December court order barring any comment on settlement negotiations.

Steel and Willson, who has become a popular speaker at anti-war rallies and conferences on Central America, hailed the proposed settlement as a significant reminder of the cost of harsh action against peaceful demonstrations. "It is an important lesson in how the government should deal with dissent," Steel said.

But Willson, 49 -- he was born on the Fourth of July, 1941 -- also called it a "bittersweet victory," for he and other activists have not yet seen much change in what they consider a militaristic American stranglehold on the lives of Central Americans who want to create their own societies and economies.

"I'm pretty discouraged," Willson said, adding that he hoped the work of protesters and organizers like himself in the 1980s would bear fruit with rejection of U.S.-backed Central American governments in the 1990s. He served as an observer of the February elections in Nicaragua and was "shocked, and in deep anguish and grieving" when the revolutionary Sandinista party lost. The new government of President Violeta Chamorro "is a U.S. client government," Willson said, "so it can't possibly represent the Nicaraguan people."

Although the proposed settlement would be one of the largest ever won in such a case, almost all of it may go to legal costs and Willson's huge medical bills. (Willson said he could not be specific about how the money would be allocated.) Steel said that Willson, an attorney and former Air Force captain in Vietnam, has spent more than $100,000 on medical treatment for the severed legs and skull fracture he suffered in the incident, and that there will be "some hundreds of thousands in future medical bills."

When the train hit him on Sept. 1, 1987, Willson had been living on meager resources as a full-time organizer of nonviolent peace protests. He continues a modest existence in San Francisco's Haight-Ashbury neighborhood with his wife, Holley Rauen, a midwife. Rauen was participating with her husband of 11 days at the demonstration 30 miles northeast of San Francisco when the train struck and was one of the four other plaintiffs in the lawsuit.

Willson had engaged in a 36-day fast outside the U.S. Capitol in 1986 and had announced he was about to begin a 40-day "Fast for Life and Peace" outside the naval facility, which had been a source of arms shipments to U.S.-backed governments in Central America. Six of the seven demonstrators sitting or kneeling on the tracks jumped off when the train engineer blew his horn, but Willson failed to move.

Although his memory of the incident is gone, Willson said he thinks "I so believed that the train would stop" that his realization of the danger came too late.

Shortly after the incident, Navy officials said train personnel had not expected to find people on the tracks and that the locomotive was traveling at only 5 miles per hour, as required by base regulations. Steel said later investigations indicated the speed was as high as 17 mph and that the crew failed to brake in time despite having a clear view of the demonstration 600 feet down the track and needing only 143 feet to stop.

Steel said his theory is "they were trying to teach the demonstrators a lesson."

The Navy's legal case was not helped by a Pentagon decision two months after the incident to put disciplinary letters in the personnel files of Capt. Lonnie Cagle and Cmdr. Clayton Y.K. Ching, the installation's two top officers, for failure to assure safe operations. During depositions in preparation for the lawsuit, several base employees told Willson's lawyers that the train crew was aware of plans for a demonstration and possible sit-down that day.

Steel said one supervisor told the train conductor there would be a confrontation with demonstrators "sooner or later, so we might as well have it now." Navy officials denied the remark suggested any intent to harm any protesters.

Since the tragedy, Steel said, small groups of demonstrators have stopped every train that has left the weapons depot. Several times a week, in a routine that now seems choreographed, one or two protesters sit on the tracks and are arrested by Contra Costa County sheriff's deputies so the train can proceed. Willson estimated the total number of arrests now exceeds 1,500, and there are no plans to stop.

The other plaintiffs in the case are David Dunscombe, a military veteran and chaplain now serving a 30-day jail sentence for blocking some of the trains, freelance journalist Michael Kroll and military veteran and tree trimmer Duncan Murphy.

Willson now spends part of his time teaching a course on "Vietnam: Rhetoric and Reality" at San Francisco State University and fights a weight problem. At 6-2 3/4 (now only 6-2 with artificial limbs), he was an avid basketball and softball player before the train hit him but can no longer run. Earlier this year, however, with the aid of a pinch runner, he blasted a home run in his first softball game at-bat since losing his legs.

His doctors tell him his head injury kept his brain from processing memories of the train collision and that moment will always be a blank. "I'm glad," he said. "I'm not in any hurry to regain the memory."