United 93
Investigators comb the debris field for the flight data recorders from United Airlines Flight 93 near Shanksville, Pennsylvania in this September 12, 2001 file photo. Reuters

On the morning of 9/11, rookie fighter pilot Lt. Heather Lucky Penney put her jet on a crash course with United Arlines Flight 93, embarking on a potential act of heroism that was eclipsed by a greater sacrifice.

The World Trade Center and the Pentagon had already been struck when Penney took to the sky on the morning of 9/11, determined to bring down a fourth plane that was hurtling toward Washington, D.C.

But in the scramble to respond to the unexpected assault, Penney had not had time to arm her plane with any ammunition or missiles. As Penney and her wing mate, Col. Marc Sasseville, flew northwest from Andrews Air Force Base, she had a directive that flight school had never prepared her for.

We wouldn't be shooting it down. We'd be ramming the aircraft, Penney told The Washington Post. I would essentially be a kamikaze pilot.

The suicide maneuver didn't end up being necessary, as the passengers of Flight 93 famously managed to overwhelm their hijackers and force them to crash the plane into a field in Pennsylvania. Penney and Sasseville aborted the mission, and Penney later flew a plane that escorted a suddenly very vulnerable-feeling Air Force One.

The real heroes are the passengers on Flight 93 who were willing to sacrifice themselves, Penney told the Post. I was just an accidental witness to history.