actually, it's not fireworks. The guy was legitimately trying to seriously fuck up the plane, by causing a fire, an explosion, and bring it down. He says he is connected by al queda, but that could just be aspirational. He had some bag of explosive powder and a syringe of chemicals that he tried to mix. people started attacking him and prevented him from going through with it.
Why would he wait until near landing to do this? Well, the route from amsterdam doesn't fly much over the US until detriot, so if he wanted to bring a plane down, hed prob want to bring it down over america, and over a population center. The only other place I could see would be over the ocean where the plane wouldn't be able to make an emergency landing if he failed.
To the 9/11 conspiracy kid. Listen to yourself...WTC 7 coming down at a speed faster than freefall? You know you're right, when those government engineers went in to fake the terrorist attack and bring the building down, they decided to pull it down faster than freefall for a more dramatic effect for the news, thinking no one would notice.
Dude, these were not amazing maneuvers that the terrorists did. They spent extensive hours in training before, and while they are different planes. the WTC is not a small target.