Michael Hingson was in his office at the data-protection agency Quantum on the 78th floor of the World Trade Center’s Tower One when he felt and heard the thud of the first airplane hitting the building, 15 floors above. Hingson, who has been blind since birth due to an eye disorder called retinopathy of prematurity, realized the crash had also roused his guide dog, a yellow Labrador named Roselle, who had been asleep under his desk. As the structure tilted, the longtime Californian took shelter in a door frame until it became clear that the shaking was no earthquake.