Defence in Depth
On the 20th of April 2010, the Macondo blowout in the Gulf of Mexico became the biggest oil spill in US history. Five million barrels of oil is the rough estimate, about twenty times the size of the Exxon Valdez oil spill in Alaska in 1989. Apart from being an environmental catastrophe, the Macondo was also a human disaster with 11 people killed.
The real causes of the accident are the human and organisational factors which we find at work in many other big accidents.
The idea of defence in depth is that we need more than one safety barrier or defence, because each defence is fallible. Since we cannot rely on any one defence, we must do our best to make sure that all the defences are functioning as well as possible. If we decide that a particular test we are doing is basically redundant because we believe that the first defence is effective, then we are not operating in accordance with the philosophy of defence in depth.
In this process safety training video Professor Andrew Hopkins looks at the real causes of the accident. The human and organisational factors that can be found at work in many other big accidents.