"Dad," Peter Hanson said in a hushed voice, "I think they're going to crash the plane."

The 32-year-old software salesman, seated on United Flight 175 Tuesday next to his wife, Sue, and 3-year-old daughter, Christine, spoke to his father, Lee, twice from the aircraft, friends of the family said yesterday.

During the first call, apparently made in secret, Hanson told his father that the Los Angeles-bound plane had been hijacked. The second time, he confided that he thought the flight was doomed.

The young parents and their outgoing preschooler were beginning a quick vacation to Disneyland and a visit with Sue Hanson's relatives on the West Coast. One of her brothers had thought she was taking a later plane, but United later confirmed that the family was together on Flight 175.

The Hansons moved to a newly built Colonial in Groton three years ago, seeking a quieter life for their baby than Boston offered. Peter Hanson became an ambitious landscaper, planting more than a dozen seedlings on his half acre with Christine pitching in, while Sue Hanson, a lab technician and doctoral student in immunology at Boston University, loved the peace and calm of this northwest town.

"Sue loved seeing the stars over Groton," said one next-door neighbor, who asked not to be named. "It always helped her relax."

Another neighbor, Karen Forbes, who has a son of Christine's age, said she had rushed to track down her own relatives and close friends Tuesday to make sure none of them were flying that morning. Then another friend called with word about the Hansons.

"It was just such a surprise, and so sad," Forbes said. "Sue was brilliant. Peter was such a good and loyal man. And Christine was a real ball of fun."

Professor Hardy Kornfeld, who was Sue Hanson's thesis adviser at the BU School of Medicine, hired her in 1992 as a lab assistant. Her talent quickly became apparent. With his encouragement, she entered the doctoral program and began a series of challenging experiments creating mice that lacked the InterLeukin-16 gene. She studied the role that the gene may play in both asthma and AIDS.

"She basically did it all by herself - she was a terrific scientist," Kornfeld said, "and one of the nicest people." He said he expects BU to award her a doctorate posthumously, and he said he would attempt to finish her project and publish an article about it in a science journal, with Sue as the lead author.