United Airlines Flight 93 was headed for San Francisco on Sept. 11, 2001, but terrorists hijacked the plane and it never arrived.
Next week, a group of family members, friends and supporters of the plane's 40 passengers will leave San Francisco to start "Ride With the Forty," a cross-country motorcycle trip in their memory and in honor of the 10-year anniversary of their deaths.
The group will leave Monday from near San Francisco International Airport, where the plane was supposed to land, and will arrive on Sept. 11 at a field in Pennsylvania where the plane crashed exactly 10 years earlier.
Flight 93, one of four planes hijacked by the terrorists that day, was the only one that did not cause further destruction when the 40 passengers on board overcame the hijackers, causing the plane to crash in the field near Shanksville, Pa.
The Ride With the Forty campaign was started in 2009 by the family and friends of Louis "Joey" Nacke, one of the passengers who died on the flight.
His brother Ken Nacke will be one of the people making the trip again this year.
"It's a labor of love," Nacke said. "It's all about the 40, not just my brother, all 40 of them."
Along with celebrating the lives of the passengers on the plane, the trip is helping to raise money to fund the construction of the permanent Flight 93 National Memorial.
The National Park Service plans to have the first phase of construction on the memorial done in time for this year's anniversary, with the second phase expected to be completed by 2014.
In 2009 and 2010, the first two years of the Ride with the Forty campaign, riders traveled along the planned path of Flight 93, from Newark International Airport in New Jersey to San Francisco.
But for the 10-year anniversary, the group decided to switch up the trip to have it start on the West Coast and end at the passengers' final resting place.
"We decided to reverse it to try to bring as many riders as we can to the opening of the national park for Flight 93," Nacke said.
There is also a southern route of the trip starting Monday in Los Angeles, where riders will head east toward the memorial as well, he said.
The northern route of the trip begins at 7:15 a.m. Monday at Dudley Perkins Harley Davidson, a motorcycle dealership located in South San Francisco just north of the airport.
Dozens of people are expected to either ride along with the group on the various legs of the trip or greet them when they arrive at their daily stops, Nacke said.
Nacke said he hopes that the trip will keep the sacrifice of the 40 passengers fresh in the public's memory.
"We want ... them to be honored, cherished and remembered for generations to come," he said.
For more information on the Ride With the Forty trip and the 40 passengers of Flight 93, or to donate money toward the memorial, visit www.ridewiththe40.org.