Anderson Cooper 360
>> there was a pancake effect. it was almost symmetric and vertical and what that causes is the structure to come straight down, instead of collapsing sideways or collapsing in any, other trajectory. which would mean that, whatever caused it, which is unknown, at this point, would have caused the structure to have a clean-vertical collapse of those towers. >> reporter: but while engineers continue to speculate from afar, in reality, the answer lies, like the victims, trapped under rubble. the 40-year-old structure was due for massive repairs. an alarming 2018 inspection re report warned of abu...