On January 28, 1986, NASA was planning to launch the space shuttle Challenger from Kennedy Space Center—a mission that included a schoolteacher named Christa McAuliffe. The launch had already been delayed a few times. On the night before the new launch date, NASA held a long conference call with engineers from Morton-Thiokol, the contractor that built the Challenger's solid-rocket motors. Allan McDonald was one of the Thiokol engineers.

On the day of the launch it was unusually cold in Florida, which concerned McDonald because he feared that his company's o-ring seals in the Challenger's big joints wouldn't operate properly at that temperature. Since the boosters had never been tested below 53 degrees McDonald recommended the launch be postponed again.

But NASA officials overruled McDonald and requested that the "responsible Morton-Thiokol official" sign off on the decision to launch. McDonald refused to sign the request, but his boss did. The next morning McDonald—and millions of people around the globe—watched as a mere 73 seconds into the flight, the shuttle burst into flames.

After the accident, a review showed the cause of the explosion to be what McDonald had feared: the o-rings failed to hold their seal in the cold temperature. In other words, some people in the know had foreseen the exact cause of failure. So why, even with that warning, did NASA push on? Allen McDonald claims that NASA fell prey to the oldest and most basic sin—pride. McDonald said:

NASA [had become] too successful. They had gotten by for a quarter of a century and had never lost a single person going into space … And they had rescued the Apollo 13 halfway to the moon when part of the vehicle blew up. Seemed like it was an impossible task, but they did it. So how could this cold o-ring cause a problem when they had done so much over the past years to be successful? [All of this success] gives you a little bit of arrogance you shouldn't have … But they hadn't stumbled yet and they just pressed on.