An artist’s drawing depicts the aircraft approaching the Pentagon, moments before the plane’s right wing struck the portable generator. Its left engine then struck the low concrete wall surrounding the outside ventilation structure, at almost the same instant as the plane’s nose hit the building.

For a dynamic simulation of the Pentagon crash, including damage to the generator, vent structure, and nearby light poles, see 911 Case Study: Pentagon Flight 77, at youtube.com. (© The Pentagon Building Performance Report)