Risk control and dependability

7 June 2011

As part of a PEE(Programable / Electrical / Electronics), the analysis of dependability of a system must fit into a risk management overall.

Indeed, the analysis of dependability of a PEE system can allocate a level of confidence in the safety, reliability, availability and maintainability of the functions for which it was designed. These PEE systems are developed for the most part, to protect human environments in which it operates


  • An ESP is a safety system that allows a vehicle to follow the path defined by its driver.
  • An ABS is a safety system that allows the driver of a vehicle to slow down without locking the wheels.
  • A Platform Screen Door is a safety system that will prevent passengers from falling on the tracks.
  • An overspeed control is a safety system that allows a process to trigger an emergency brake in excess of its authorized speed.
  • A system of computerized aircraft flight is a safety system that allows the driver to limit the evolution in his plane.

But in all these examples, the high level of dependability of each item of equipment, not enough to ward off human accidents, it is not incorporated in a more comprehensive risk management.

Indeed, a driver designates an ESP system will rely on its safety system and move his attention elsewhere in the turns. Similarly for a driver equipped with an ABS system, it will shift its attention away from the safe distance. A passenger waiting for his subway will enjoy the safety system that covers up the track to enjoy the maximum space of the platform. Train drivers will rely on the safety of the speed controller to move its attention to other maneuvers. The pilot of aircraft will be based on the security system of the flight control computer to hire new workers.

Thus, a safety system can not alone replace the vigilance of its users. This decrease in alertness, reflected through changes in behavior must be incorporated into the overall risk analysis that integrates all other between the awareness and prevention, to take into account all the risks that will be induced by Installation a system in its environment.