Biden will be the keynote speaker at the Flight 93 National Memorial in Shanksville, where the hijacked United Airlines plane crashed. The 40 passengers and crew died in what investigators later determined was a struggle with hijackers for control of the jet.
The names of the passenger and crew will be read at 10:03 a.m., the moment the plane crashed - and bells of remembrance will be rung by surviving family members and community members who became involved in the aftermath of the crash.
A wreath will also be laid at the memorial's Wall of Names.
