Communication lapses lie at the root of many mishaps and close calls and can set off complicated event chains that lead to disaster. One such string of mistakes took place in the weeks preceding Space Shuttle Columbia's maiden voyage in March 1981. A countdown demonstration test had just concluded, and controllers opened the pad area for normal work. The controllers did not know that a hazardous condition — an atmosphere of pure nitrogen — still existed in the shuttle's aft compartment. Without warning signals or other indications of the oxygen-deficient space, technicians entered the area and collapsed just seconds later. Over the course of 15 minutes, six technicians were exposed to the nitrogen atmosphere, and three of them eventually died because of it. This was the third successive time that tragedy struck the inaugural mission of a human spaceflight program. This story illustrates the prevalent and far-reaching effects of systemic safety issues and reminds us of the vigilance required to keep those failure modes at bay.