An aluminum, hollow airliner is far more fragile and much less dense than the WTC Towers. In reality, collision with a WTC building would result in wings, fuselage and other plane parts adhering to the face, many pieces falling to the ground below and heavier ones such as engines and the landing gears maybe entering the Tower between the steel columns.

In a real plane/Tower impact, wing tanks would have ruptured instantly and burning jet fuel would have streamed down the front of the building.

Watch September Clues..parts 1-8 here on You Tube!!