9/11: The Day That Changed America

David Muir interviews survivors and family members who lost loved ones in the attacks on the World Trade Center, the Pentagon, and United Flight 93 in Shanksville;David Muir interviews survivors and family members who lost loved ones in the attacks on the World Trade Center, the Pentagon, and United Flight 93 in Shanksville;David Muir interviews survivors and family members who lost loved ones in the attacks on the World Trade Center, the Pentagon, and United Flight 93 in Shanksville;