When the car runs out of gas on a remote backroad, it’s not the vehicle system that failed, but the gas supply system. When a vehicle has a flat tire on a busy highway, it’s not the vehicle system that failed, but the tire system. When an aircraft excurses a runway, it’s not the aircraft system, or airport system that failed, but a sub-system of the aircraft or the airport, or any one of these undesired events could have been caused by the human performance capability system or the level of comprehension of any of these systems. During the history or aviation, the aviation industry became safer without the requirement to conduct safety cases. Building safety cases with the introduction of new aircraft type, change in route structures, additions to the movement area or change in key personnel were a part of ongoing changes and adapting to these changes as they occurred.
|A safety case will be your most precious friend of aviation SMS|
A safety case is a forward-looking document produced by an airline or airport of identified hazards, analyses of the hazards and building a safety case with risks control strategies. The focus of a safety case is to operate with a plan to reduce the risk for both regulatory non-compliance and operational incidents. An Enterprise develops a safety case pursuant to the Safety Management System and not pursuant to regulatory demands. There is a close relationship between the SMS and the safety case. The safety case is guidance material for safety activities while SMS provides processes for these activities. In addition to the application of current corrective action plans, a safety case is a reference document for airlines and airports for future system-identical planned changes or when unexpected changes are experienced.
|A safety case is a tool to validate findings|
Building a safety case is a proactive process of the Safety Management System. Since it is proactive, the intent of building a safety case is not a reactive action to planned events, but a proactive action to operational sub-systems. The reason for a safety case is simply to have a documented forward-looking plan for all systems and apply this plan when there are changes to the system. Building a safety case is therefore very different than corrective action plans required from findings. There are no findings involved in building a safety case, but hazard analysis and risk assessment of operational sub-systems are involved.
A successful airline operator plans for future introductions of new aircraft and new routes. A safety case of is simply to analyze and assign the expected probability risk level at the time of introductions of these new sub-systems. When the time is right, the airline is prepared for these changes. The same goes for airports. Airport management knows that sooner or later they must repaint the runway identification numbers. Even if there is no traffic on the runway to deteriorate the numbers, the magnetic variation changes over time and requiring repainting. A safety case as a forward-looking plan is a plan for the movement area marking system. When the time is right, the airport is prepared to make changes to the this system.
When building a safety case, it is vital to the success for acceptable performance of the system that the person building a safety case comprehend the system itself. In addition to comprehending the system, the person must comprehend the interactions of one system with other systems, both externally and within the operations. A safety case can only be built as a blueprint of a forward-looking plan.