Just last week, Eckert was at the White House with Barack Obama, part of a meeting the president had with relatives of those killed in the 2001 attacks and the bombing of the USS Cole to discuss how the new administration would handle terror suspects.
"She was such an important part of all of our work," said Mary Fetchet, another 9/11 family activist. She learned Eckert was aboard the plane from another close Eckert family friend now headed to Buffalo. Officials investigating the crash have not yet confirmed she was on board the plane.
Eckert, who was flying to Buffalo to celebrate what would have been her husband Sean Rooney's 58th birthday, was one of the most visible, tearful faces in the aftermath of the terror attacks.
She cried as she told the story about how her husband — her high school sweetheart — was on the phone in the World Trade Center telling her he loved her when suddenly there was a loud explosion and nothing more.
She carried that grief to Congress as she tried to make the government do a better job protecting its citizens from terrorism.
Eckert was part of a small group of Sept. 11 widows, mothers, and children who became amateur lobbyists, ultimately forcing lawmakers in 2004 to pass sweeping reforms of the U.S. intelligence apparatus.