Originally Posted by rickair7777

Tall buildings were designed to withstand internal fires, not vast quantities of Jet A which are not normally present. They have foam-insulated steel structures for that reason. The 9/11 impacts stripped the foam off the steel structure around the impact site, making matters worse.

There are limits, but we could easily build something which could withstand max possible impact forces of an airliner. We're not talking about a spaceship hitting something at some astronomically high speed which would result in nothing but plasma.

Assume a max vertical arrival speed of something like mach 2 or thereabouts (the airframe of an airliner would disintegrate and slow down at some point prior to that). This would account for a deliberate full-power dive.

Assume X amount of fuel that would burn at Y temp for Z hours.

It's not so much about the materials, but rather the construction. A multi-layered container with materials which could deform to absorb impact, with some layers of thermal material and possibly a semi-passive cooling system (a fluid or solid which evaporates to remove heat). The airframe itself provides a lot of impact absorption, that's why the recorders are located in the tail...the only real extreme impact scenario involves a head-on arrival with the ground (or a mountain), either deliberate or wings-off lawn dart scenario. If the plane comes apart, aerodynamic drag will result in relatively low impact forces.

That's well within our technical limits. It would just be more expensive than what we have now, which works most of the time. Also it would be heavier and bulkier, which means it would cost more money on every flight.