About Preliminary Risk Assessment (PRA)

The Preliminary Risk Assessment (PRA) is performed on a system instantiated in its environment. The system to be analyzed corresponds to a logical component. This component implements functions, which are subject to functional failures regardless of how these functions are implemented. The logical system is considered as a black box and needs not (and should not) be refined at the stage of Preliminary Risk Assessment. An analysis can be realized in one-off hazard analysis or can be broken down into many hazard analyses.

This page discusses:

Preliminary Risk Assessment Depending on Domains

Depending on domains and handled elements, the PRA names and content vary. Two templates corresponding to automative systems and aerospace systems are provided by default in the app:

Hazard Analysis and Risk Assessment (HARA)

HARA is a method to:

  • Identify and categorize hazardous events of systems.
  • Specify safety goals and ASILs related to the prevention or mitigation of the associated hazards to avoid unacceptable risks.
HARA complies with the ISO26262 standard.

Functional Hazard Assessment (FHA)

FHA is a method to identify and categorize failure conditions of functions according to their severity. FHA complies with the ARP4761 standard.

Additional templates can be inserted in the app.

Principle

The principle below is presented for a PRA HARA on a logical system.

The first step of a PRA is to identify the system to be analyzed.

The PRA of a logical component identifies the failure modes of each function implemented by the logical component and the hazardous events that can cause them.

A logical component needs to be considered with its context of the whole system. This occurrence has attributes that are features of this unique logical component.