Unironically, an airliner plane would have a much bigger payload than most missiles. Way more mass, and filled to the brim with flammable fuel.
but jetfuel can't melt steel beams
A fuel-fed fire will blaze for a long time. When trapped in a building, that heat becomes an inferno. The fire can massively weaken the integrity of the supports in the building. With the crushing weight of the rest of the building, it's not hard to believe the building would collapse.
Planes are mostly filled with empty space. The fuel is in two tanks in the fat parts of the wings. In a catastrophic plane crash, at top speed say, maximum destruction, the majority of that fuel burns off in the fireball resulting from crash impact. Fires are then prolonged by whatever other "fuel" is present at the location of the crash which was set alight by it - for example the wreckage of the plane itself and the matter it crashed into. The flammability of that material, and access to oxygen, would be the determining factors as to how long that fire would last.
And every floor would have provided resistance all the way down. Which in turn would slow down. Everything is just not going to give out and crumble to the ground.
Unironically, an airliner plane would have a much bigger payload than most missiles. Way more mass, and filled to the brim with flammable fuel.
A fuel-fed fire will blaze for a long time. When trapped in a building, that heat becomes an inferno. The fire can massively weaken the integrity of the supports in the building. With the crushing weight of the rest of the building, it's not hard to believe the building would collapse.
The building becomes it's own blower.
Planes are mostly filled with empty space. The fuel is in two tanks in the fat parts of the wings. In a catastrophic plane crash, at top speed say, maximum destruction, the majority of that fuel burns off in the fireball resulting from crash impact. Fires are then prolonged by whatever other "fuel" is present at the location of the crash which was set alight by it - for example the wreckage of the plane itself and the matter it crashed into. The flammability of that material, and access to oxygen, would be the determining factors as to how long that fire would last.
So what weakened the bottom 80 floors?
The sheer weight and momentum of the top floors crashing down.
And every floor would have provided resistance all the way down. Which in turn would slow down. Everything is just not going to give out and crumble to the ground.