The documented result of Safety Assurance is often known as a Safety Case – particularly for new systems and procedures. It is a documented body of evidence that provides a demonstrable and valid argument that a system is adequately safe for a given application and environment over its lifetime.
A Safety Case is a statement of how Safety Managers, Ops. Managers and others, intend to manage their own risks, and thus prove that systems and procedures, new or revised, are safe for operational use and meet the target level of safety. Put another way, it is a structured argument, supported by a body of evidence that provides a compelling, comprehensive and valid case that a system is safe for a given application in a given operating environment.
Broadly, the Safety Case is the documented assurance (i.e. argument and supporting evidence) of the achievement and maintenance of safety. It is primarily the means by which those who are accountable for service provision or projects assure that those services or projects are delivering [or will deliver] and will continue to deliver, an acceptable level of safety.
A Safety Case is also a form of Business Case, i.e., it can be used to show investors, bankers, Customers, insurers and corporate managers, etc. that the risks associated with a project have been formally and comprehensively analyzed and that the associated risks are subsequently demonstrable to an acceptable level.
A Safety Case is built upon the following three principles:
- Those who create risks are responsible for controlling those risks.
- Safe operations are achieved by setting and achieving goals rather than by following prescriptive rules.
- All risks must be reduced such that they are below a threshold of acceptability.
Airports, Aerodromes & Heliports, Fixed & Rotary Wing Operations, Manufacturing, AMOs.
- Unit Safety Case:
- Project Safety Case:
Unit Safety Case (USC): An Organisation may decide to produce or maintain a Unit Safety Case in order to show that the on-going, day-to-day operations are safe and that they will remain so indefinitely. A Unit Safety Case will typically include a prior Safety Assessment (to show that a service and/or system is predicted to be safe) together with the results of safety audits, surveys and operational monitoring (to show that up to that point in time, it actually has been safe). It should also demonstrate that processes are in place to ensure that all future changes to the system and/or processes etc. will be managed safely through (inter alia) a Project Safety Case.
Project Safety Case (PSC): An Organisation may also decide to produce a Project Safety Case when a particular substantial change to an existing safety-related service and/or system (including the introduction of a new service and/or system) is to be undertaken. A Project Safety Case would normally consider only those risks created or modified by the change and rely on an assumption (or evidence from the corresponding Unit Safety Case) that the pre-change situation is at least tolerably safe. A Project Safety Case is normally used to update and is usually subsumed into a Unit Safety Case(s).