The aspect of safety management addressing hazards that lead to accidents on the scale of one or a few workers, such as slipping and falling or injuries that occur during a crane-lifting activity, is commonly termed occupational safety (also referred to as personal safety or worker safety). In contrast, other offshore drilling hazards can lead to accidents on a much larger scale, potentially involving multiple fatalities, substantial property loss, and extensive environmental damage. Hazards that can cause catastrophic effects are within the realm of system safety.1 This term refers to an engineering and management approach used to ensure that safety is built into a system with the objective of preventing or significantly reducing the likelihood of a potential accident. [See Rasmussen (1997), Rasmussen and Svedung (2000), and Leveson (2011) for additional discussion of system safety.]
The Ocean Ranger mobile offshore drilling unit (MODU) incident in 1982 involved a failed ballast control system and a ballast control operator who was not properly trained to respond to this particular event (Hickman 1984). The MODU sank and all personnel were lost—most, if not all, because of the harsh cold conditions. Industry’s response to the Ocean Ranger disaster resulted in a major shift in ballast control training and the introduction of simulators to train ballast control operators. The disaster also led the offshore industry to improve the training of rig personnel in survival skills and the procedures for abandonment of a drilling vessel. Those efforts encouraged the worldwide development of survival schools. Industry’s response to the event also demonstrated the need for a preemptive overall safety strategy. Even though the Ocean Ranger disaster was not a well blowout event, it demonstrated the importance of understanding the ramifications of the total system safety of an offshore operation.
Another example is provided by the Piper Alpha platform disaster, which occurred in the North Sea in 1988. A gas leak resulting from a faulty maintenance operation ignited and exploded on the platform, causing a large-scale fire and a disaster that resulted in 167 deaths. The incident showed what damage could occur essentially from an accumulation of management errors (Cullen 1990; Paté-Cornell 1993); it became a turning point in the way industry addressed the safety of its offshore operations. Furthermore, the U.K. government changed the way it regulated the offshore oil and gas industry by moving to a performance-based form of regulation, sometimes referred to as a safety case approach (see Chapter 6).
Although a company’s fundamental approach to safety can affect both occupational and system safety, an effective occupational safety program will not necessarily be indicative of an effective approach for managing system safety. Larger-scale accidents can arise from many different causes that are mostly unrelated to the factors targeted by occupational safety programs. However, an effective system safety program can result in reduced injuries and save lives (CCPS 1992). Therefore, both types of safety are of value to workers. Given the
1 In some industries (e.g., chemical) the term is also referred to as process safety.