Guideline: Hazard Analysis Guideline
This guidance addresses the content and format of a hazard analysis.
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Main Description

A hazard analysis is a central repository for information around system hazards, risks, and control measures. This includes the following categories of information:

  • The nature of the hazard.
    What can happen? What faults can lead to the potential accident?
  • The quantification of risk.
    How severe? How likely?
  • The timeframe of concern.
    How long can the fault be tolerated? How long to detect it? How long to handle it?
  • The control measure.
    What design features or procedures will be put into place to address the hazard and/or fault condition?

The table below shows and example of such an analysis for a medical ventilator.  

Hazard or Loss Fault Severity (1-10) Likelihood Computed Risk Time Units Tolerance Time Detection Time Control Measure Control Time
Hypoventilation Breathing tube disconnect 10 0.2 2 minutes 5 0.5 Blood O2 Sensor 2
Hypoventilation Ventilator timer error 10 0.2 2 minutes 5 0,5 Pressure sensor with alarm 2
Hypoventilation Gas supply failure 10 0.4 4 minutes 5 0.05 Gas pressure sensor 2
Hypoxia Gas mixer failure 10 0.6 6 minutes 5 0.05 Aspiratory O2 sensor 2
Hyperventilation Ventilator timer error 8 0.1 0.8 minutes 20 0.5 Blood O2 sensor 2
Overpressure Pump failure 10 0.3 3 ms 200 10 Secondary release value 5
Overpressure Expiratory tube blockage 10 0.5 5 ms 200 10 Secondary release value 5

The hazard analysis is a key document in safety critical systems and is actively maintained through most of the development lifecycle. It's initial construction occurs during requirements analysis (although control measures are most often not specified at this point), all the way through design and test.