When flames and the sound of an explosion shattered the calm on a flight from Amsterdam to Detroit, one passenger instantly took action.
Jasper Schuringa climbed over seats and rushed up to where a Nigerian man was holding a burning piece of plastic -- the apparent remnants of a homemade bomb he had allegedly tried to detonate.
Amid the screaming, smoke and chaos, as many passengers ran away from the explosion, Schuringa knew it was a life or death situation and someone had to take action.
He wrenched the burning plastic from Umar Farouk Abdulmutallab's hand, then restrained him as others used fire extinguishers and blankets to put out the fire.
"When I saw the suspect, that he was getting on fire, I freaked, of course, and without any hesitation I just jumped over all the seats," Schuringa told CNN in a recent interview about the 2009 altercation aboard Northwest Airlines Flight 253.
"And I jumped to the suspect. I was thinking like, he's trying to blow up the plane."
In December 2001, just a few months after 9-11, passengers aboard American Airlines Flight 63 also risked their own lives to halt a would-be terror attempt.
Richard Colvin Reid, later known as the "Shoe Bomber," was struggling to light the fuse to a bomb he had concealed in his shoe when flight attendants, and then passengers, intervened and bound the man in plastic handcuffs, seatbelts and telephone cords.
And in perhaps the most vivid example, passengers aboard Flight 93 on Sept. 11, 2001 fought with hijackers after learning by cell phone that two planes had hit the World Trade Center, and they were likely next.
Though all 44 people on board were killed when the plane went down in Pennsylvania, their efforts are widely credited with causing the plane to crash short of its intended target -- potentially sparing thousands of lives.
The willingness of Schuringa, and the passengers aboard flights 63 and 93 to risk their own lives to stop an in-flight terror attack reflects a new sense of desperation when passengers find themselves in hijacking situations, according to a number of experts.
Ramy Elitzur, an airline specialist at the Rotman School of Business, said he believes airliner hijackings are virtually impossible in the post-9-11 environment.
No longer do passengers have a reasonable expectation that hijackers will simply land the plane at a destination of their choosing, and passengers will eventually be released unharmed after demands are met.
"Today I think hijacking of planes is not possible, but not because of security measures," Elitzur told CTVNews.ca. "It's because passengers would not let it happen. Once upon a time they'd say let it run its course but now you understand there is no way out, you better fight."
Richard Miniter, an author and investigative journalist who has written extensively about post-9-11 terrorism, said there was a shift in the 1970s in the attitude toward hijackers who often wanted to exchange their captives for political prisoners.
It simply wasn't in their interest to kill passengers, Miniter said, and law enforcement agencies began recommending that hijacking victims co-operate with their captors in order to achieve the least loss of life.
But on the morning of Sept. 11, 2001, that changed. Passengers realized that simply co-operating, or keeping their heads down during a hijacking, would not only likely end in their death, but in massive destruction on the ground.
"The country realized that what law enforcement and political leaders had been telling them for three decades, just co-operate and things will be fine, was really just an unproven theory," Miniter told CTVNews.ca.
The passengers on Flight 93 can be seen as a microcosm of a psychological shift that took place, he said. After the plane was taken over by hijackers, passengers began using their cell phones to call their families.
In doing so, they learned that the World Trade Center was being attacked by jetliners similar to theirs, and their plane was likely part of the terrorists' blueprint.
One passenger, Todd Beamer, after explaining that he and other passengers planned to intervene, recited the Lord's Prayer over the phone with an airline supervisor and uttered the now-famous phrase "Let's roll," before taking action.
Miniter said that moment represents a profound shift.
"There is a natural human desire to want to protect others when you're in a life and death situation and the calculation goes like this: If I don't get out of my chair I'm going to die. If I do attack the hijackers I might die anyway but if I do die...I might be saving someone on the ground, I might have a legacy."
Armand de Mestral, a professor at McGill University and chair of the Institute of Air and Space Law, told CTVNews.ca it's difficult to prove a psychological trend.But at least anecdotally, he said, it certainly appears passengers are more willing to put themselves at risk now, than in the past.
"It may not be an entirely new phenomenon but people are more aware of the dangers and are more conscious of the risks and more likely to report or to be nervous of anything out of the ordinary," he told CTVNews.ca.
In the new era of vigilant, tense travellers what is perhaps most surprising, said Miniter, is that there haven't been more instances of passengers over-reacting based on their fellow passengers' religion, skin colour or dress.
In the weeks and months after 9-11, many predicted a violent and racist backlash against Muslims.
"What I don't see happening is what everyone predicted, that there would be an anti-Muslim or anti-Arab attitude emerging -- that the public would be really stupid and really almost racist. That hasn't happened," he said.
Instead, even in instances where passengers have intervened, the response has generally been reasonable. In the case of both Abdulmutallab and Colvin Reid, they were subdued and restrained but not beaten or attacked -- no vengeance was exacted.
"Really what we're seeing from passengers is a remarkable sensibility," Miniter said.
Instead of driving a wedge between Muslims and the Judeo-Christian community as many predicted, the tragic events of 9-11 in many ways brought them closer together, Miniter said.
People on all sides recognized a need for interfaith dialogue and deeper understanding.
"We do end up finding the basic humanity in each other," Miniter said. "We were so worried after 9-11 of extreme racism, it provoked a lot of people on both sides to say ‘Hey, maybe we should talk to each other.'"
Those conversations, Miniter said, are the positive legacy of the tragic events of 9-11.