Sandy Dahl, who became one of the tragic faces of 9/11 after her husband was killed while piloting United Flight 93, died Friday, a family friend said.
She was 52.
Dahl was found dead in her home in Colorado, but the details of her death were not released.
She had worked tirelessly running the Captain Jason Dahl Scholarship Fund and her death was a surprise, said David Dosch, a family friend.
The scholarship fund gives money to aspiring pilots to help attend commercial flight training schools.
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"Sandy and Jason Dahl were my best friends," said Dosch, who also works at the scholarship fund.
Jason Dahl was piloting United Flight 93 on September 11, 2001 that crashed in a field in Shanksville, Pennsylvania. It is believed that passengers aboard United Flight 93 thwarted a plot to drive the plane through the U.S. Capitol dome and eventually caused the plane to crash in a field.
In an interview last year on the anniversary of 9/11, Stacy Dahl wore their wedding ring.
"I do think about him every day," she told CNN affiliate KMGH. "The reason I am doing this (interview) today and the reason that I do this at all is to make sure he is never forgotten."