It was a day of infamy few of us will ever forget. As the first plane hit the towers, onlookers shook their heads in disbelief. No one would intentionally fly into the World Trade Center. No one could let it happen.

But it was happening right before horrified eyes, and even those who'd convinced themselves it had to be some sort of terrible fluke, some rookie pilot of a small plane who'd lost control, maybe a lone flyer with a medical emergency or something, finally had to admit there was something much worse going on.

There was another plane approaching, and it was clearly a jetliner. It all happened so fast it was nearly impossible to comprehend. Within sixteen minutes of each other, two commercial planes flew into the World Trade Center towers. Even then, the thought that these airliners had hit these towers intentionally would not compute. But the fact that there were two made the idea that it was a terrible accident too far-fetched to be believed.

It was hours before the truth was fully known. Mass confusion reigned on the ground. A third jet hit the Pentagon in Washington, and almost immediately, word came that a fourth was on the way, and maybe more.

Flight crews were being scrambled, but unlike today, post 9/11, not a single jet was armed and ready for combat. All on the tarmac at Andrews Air Force Base were still equipped with dummy ammunition from an earlier training exercise, and to load live ammo would take at least an hour.

There simply wasn't time.

Orders went out to intercept flight 93, the fourth airliner threat. Lt. "Lucky" Penney and her commanding officer sat ready to fly their F-16 straight into a Boeing 757. They were on the runway of Andrews Air Force Base preparing for a one-way flight to a mid-air collision, the order coming through from the White House.

"Lucky, you're coming with me," Col. Marc Sasseville ordered, adding that he would take the cockpit.

Without hesitation, Lt. Penney replied, "I'll take the tail."

Hours later, Lt. Penney and Col. Sasseville learned that their suicide mission was no longer necessary. Their jet screamed over Washington, flying low over the still-smouldering Pentagon at more than 400 mph, heading northwest.

But their suicide mission to protect American airspace was pre-empted by a passenger plane full of equally courageous souls determined that the terrorists who'd dared to attack the land of the free would never succeed.

The innocent lives lost in the towers that day remain in our hearts, and the bravery of those first responders, and Lt. Penney and her commanding officer, will forever be remembered.

 But so, too, must the passengers of Flight 93 be remembered for the pure and undaunted courage they showed in the face of what must have been overwhelming terror. That fourth airliner crashed in a field in Pennsylvania, those hostages willing to do whatever it took to stop the attack. There was no official video of that crash, no news cameras recording the devastation as it happened, but the images of those passengers' fear and determination in the face of such an horrendous end must haunt us all forever. Their plane was still flying when they made the decision to stop the hijackers. They had to know what would happen if they intervened, yet they did it.

We must never forget any of what occurred on September 11, 2001. Ever. And we must pray that our leaders do what is necessary to keep it from ever happening again.