On March 28, 1979, a nuclear power plant reacted in a manner that was incomprehensible to plant operators. Widely considered to be the most significant nuclear power plant accident in the United States, the Three Mile Island accident began as a simple mechanical failure: a failed water pump. How could such a seemingly insignificant event lead to a near meltdown? After a number of state and federal investigations, the answer became clear: the simple mechanical failure was only the first of a series of failures that were only made worse by poor decisions based on misinformation. What we’re focusing on this month is that the fact that this accident could have occurred should not have been a surprise. As you read, note the similarities between the complex systems of a nuclear power plant, and the tightly-coupled systems we use at NASA.