Part 6/9:
Investigations and Observations
Reference is made to official investigations, notably by NIST, which examined the debris and failure mechanisms. The speaker points out that parts of the steel beams showed signs of weak welding and poor design—conditions that would have compromised their ability to withstand the stresses during and after the impact.
Additional insights:
The interest of investigators in the welded joints suggests that these areas were critical failure points.
Comments that the debris includes heated steel and improperly welded components underline concerns about construction quality.