I. Premises

Failures, disasters, and tragedies occur. Catastrophic oil spills or toxic releases, mechanical breakdowns, technology failures, or software glitches may appear to be accidents, intentional acts, or environmental disasters, but almost always, human error will be involved. The human fault may occur in project design, construction, supervision, operations, maintenance, repairs and modifications, inspections, and/ or regulation. Emergency action plans (EAPs) can minimize the impact of human fault.

In some cases, the threats may be infinite, but the foreseeable damage can be predicted. For example, no matter how a dam is breached, the water will flow in only one direction. On the other hand, many disasters, such as the Deepwater Horizon blowout, will test unknown dimensions. In these situations, the risks may be infinite and on the edge of technology, such that they are not understood until disaster strikes.

In other cases, perhaps as with the Deepwater Horizon blowout, a period of success can lead to an underestimation of the risks; complacency may set in; and the decisionmakers, as with the Teton Dam and the Space Shuttle Challenger, may proceed oblivious to the underlying risks.