LOS ANGELES, DEC. 11 -- Since they learned of the chilling message scrawled on an air-sickness bag, likely the last words Raymond L. Thomson ever read, his friends have formed theories on how a man that responsible, that devoted to getting results, would have reacted to the threat that someone was about to end the lives of everyone aboard Pacific Southwest Airlines Flight 1771.

Gene Weaver, who worked for Thomson when he was Marin County, Calif., public works director, said he thought Thomson would have read it calmly, despite its awful implications.

The note, which the FBI today confirmed was written by David Augustus Burke, whose work Thomson had supervised, said, "Hi Ray, I think it's sort of ironical that we end up like this. I asked for leniency for my family, remember. Well, I got none and you'll get none."

"I think the first thing he would have thought of was to talk this gentleman out of doing anything on that plane," Weaver said. "He might have said, 'If you want to shoot me, do it on the ground and don't harm these people.' That would be my idea of Ray Thomson."

Investigators said Thomson, 48, a USAir customer service manager here, became part of the tragedy that killed him, Burke and 41 others Monday when he participated in firing Burke, a 35-year-old ticket agent, for allegedly stealing $69 from in-flight liquor sales receipts.

Thomson lived north of San Francisco and regularly commuted on PSA to and from his job as head of USAir's office in Terminal One at Los Angeles International Airport. Investigators believe Burke boarded Flight 1771 to San Francisco in Los Angeles Monday after discovering Thomson would be on it and, armed with a .44 Magnum revolver smuggled past a checkpoint, apparently gave Thomson the note before the pilot reported shooting on board and the plane crashed.

Former co-workers and friends of the trim executive, who jogged for exercise, said he asked a great deal of his employes but stood behind those who did their jobs. He apparently refused to consider Burke's repeated requests for reinstatement, and FBI investigators said he met with Burke at the Los Angeles airport three hours before the ill-fated aircraft took off.

Thomson lived in the affluent bayside Marin County community of Tiburon, a place of boats and hilly vistas just north of San Franciso. At home he generally kept to himself, neighbors said. "He wasn't the most outgoing. He usually never waved," neighbor Robin Scott told the Associated Press. "He took care of his life in a very personal way."

Thomson lived with his wife, Dorothy, a flight attendant with American Airlines, where Thomson also once worked as a service manager responsible for about 1,000 employes in San Francisco and San Jose. The couple married in 1981 and had no children. Dorothy Thomson declined to speak with reporters.

Former colleagues spoke highly of his work for Marin County, where he headed the public works department from 1980 to 1982. "He was very supportive of the Department of Public Works and continuously argued for more funding," said Mario Balestrieri, the county's current director of public works. "He seemed to be demanding at times but always fair with employes. There was never a time when disagreements got out of hand."

"He was a taskmaster of himself and everybody who worked for him. . . . As long as you did your job, he was the first one to stand up for you," said Weaver, now a Marin County building superintendent.

Thomson left the public works department because of differences of opinion with the Board of Supervisors, Marin County officials said. He was hired by USAir in July 1986 after working four years as a private consultant.