As United Airlines Flight 93 entered its last desperate moments in the sky, 31-year-old passenger Jeremy Glick used a cell phone to tell his wife, Lyzbeth, of his impending death -- and pledged to go down fighting.

Glick told his wife that the Boeing 757's cockpit had been taken over by three Middle Eastern-looking men wielding knives and a red box that they claimed was a bomb. The terrorists, wearing red headbands, had ordered the pilots, flight attendants and passengers to the rear of the plane, which was headed from Newark to San Francisco.

Lyzbeth Glick, in turn, informed her husband that another hijacked jet had already crashed into the World Trade Center, according to Glick's brother-in-law, Douglas B. Hurwitt, who had spoken in detail with Glick's wife about the 30-minute call. Authorities believe the hijackers of Flight 93 turned the aircraft around and were aiming for a target in Washington.

Glick said he and others aboard the plane had decided to rush the cockpit and try to subdue the terrorists -- a display of resistance that may have staved off a much worse catastrophe.

"They were going to stop whoever it was from doing whatever it was they'd planned," Hurwitt said. "He knew that stopping them was going to end all of their lives. But that was my brother-in-law. He was a take-charge guy."

Glick's cell phone call from Flight 93 and others like it provide the most dramatic accounts so far of events aboard the four hijacked aircraft during the terrifying hours of Tuesday morning, and they offer clues about how the hijackings occurred.

Still, much is unknown about how bands of three to six terrorists on each airliner -- apparently armed with knives, razors and box cutters -- eluded security measures, took control of the four aircraft and committed the worst act of terrorism on U.S. soil.

On Flight 93, at least, passengers said they were going to fight back.

Ten minutes into the 30-minute call with her husband, Lyzbeth Glick asked her father to call the FBI on a separate line, Hurwitt said. FBI agents monitored the last 20 minutes of the call and are studying a tape and transcript.

Glick, a sales manager for a technology firm who celebrated his 31st birthday on Sept. 3, told his wife that he hoped she would have a good life and would take care of their 3-month-old baby girl -- before the phone call faded out amid what Hurwitt described as "random noises and screams."

It is unclear what Glick and the other passengers did next, but Flight 93 was the only one of four planes hijacked on Tuesday that did not smash into a major target on the ground. Some are already describing as heroes the passengers who may have tried to thwart the hijackers' plans.

Pennsylvania Rep. John P. Murtha, the ranking Democrat on the House Appropriations defense subcommittee, said at the crash site near Shanksville, Pa., yesterday that he believes a struggle took place in the plane's cockpit. He added that he believes the plane was headed for a significant target in Washington.

"There had to have been a struggle, and someone heroically kept the plane from heading to Washington," Murtha said.

Whoever was ultimately in control of the plane, Flight 93 made a number of odd maneuvers in midair before it finally plunged to earth. "Halfway through its trip, around Weston, W.Va., it took some sharp turns, all within about two or three minutes," said Jeff Krawczyk, chief executive of Flight Explorer, a software firm that uses Federal Aviation Administration data to track flights.

"It was going west, then took a turn to the north, and then went west again," Krawczyk said. Then the plane headed toward Kentucky and took a sharp turn south toward Washington, and around that time the FAA center in Cleveland lost contact with the flight, apparently because someone on board had turned off its transponder, he said.

Brad Clemenson, a spokesman for Murtha, said the aircraft apparently made at least two other sharp turns during its last minutes -- swerves that are detectable in Flight Explorer's computerized reconstruction of the jet's path.

Dennis Fritz, director of the municipal airport in Johnstown, Pa., said the FAA called him several times as the plane approached his city, and even warned him to evacuate the tower for fear the jet was going to plow into it.

"They said the plane was very suspicious, and they didn't know what it was doing," Fritz said. Flight 93 crashed into a field 14 miles south of Johnstown.

The wife of another passenger has also spoken of farewell phone calls from her husband on board the plane in which he, too, mentioned a plan among the hostages to thwart the terrorists.

Deena Burnett, wife of 38-year-old California businessman Thomas E. Burnett Jr., said she received four calls from her husband. During the first call, he described the hijackers and told her that they had stabbed and seriously injured one of the passengers, and he advised his wife to contact authorities. She informed him that the World Trade Center had been hit by another hijacked jet.

Thomas Burnett called back shortly thereafter to report that the wounded passenger had died and that he and some others "were going to do something" to stop the terrorists, Deena Burnett told KCBS Radio in San Francisco.

Kathy Hoglan of Los Gatos, Calif., said her nephew, 31-year-old Mark Bingham, did not specifically mention a plan to tackle the hijackers in his cell phone call to her at 9:44 a.m. Eastern time.

Bingham managed to tell his aunt and mother, Alice Hoglan, only that the plane had been hijacked and that he loved them before the phone "went dead," Kathy Hoglan said. But the 6-foot-5 former University of California rugby player would undoubtedly have joined any such effort, she said.

"He was calm but scared, as if he knew something was going to happen," Hoglan said. "There's no doubt he wouldn't have let them get away with it."

Aboard the other doomed flights, passengers and flight personnel also frantically used cell phones to describe the terror unfolding in the sky.

Betty Ong, an American Airlines flight attendant aboard Flight 11, which slammed into the World Trade Center, called her airline supervisor to report that she had seen at least three hijackers with weapons and that more than one person aboard the plane had been stabbed, law enforcement sources said.

The hijackers had also told people on the plane flying from Boston to Los Angeles that they planned to crash the aircraft in New York City, the sources said.

It is unclear how that telephone call ended.

FBI agents comb through the crater left by the crash of United Flight 93 in Shanksville, Pa. Some people following the probe believe a struggle to thwart the hijackers brought the plane down.