Breaking

The simple fact that, OFFICIALLY, flights 11, 175, 77 and 93 all crashed and disintegrated to such an extent that no significant debris was left, should tell us that airplanes are not very effective at slicing into strong structures.

Really, it is much like asking if an egg can break through a wall made of popsicle sticks. No matter how fast the egg is flying, I think the egg would break upon impact and would have trouble breaking through. It is hard to imagine the egg staying intact as it breaks through the wall, then breaks apart on the other side.

Or imagine throwing a drinking glass at a chain-link fence. No matter how fast the glass is thrown, I think the glass would break upon impact and would have trouble breaking through the wires. It is again hard to imagine the glass staying intact as it breaks through the fence, then breaking apart on the other side.