Preliminary Hazard Analysis
*** If you are looking for Process Hazard Analysis, which is also is abbreviated PHA (sometimes PrHA), please click here. ***
Preliminary Hazard Analysis (PHA) is called up by Task 202 of MIL-STD-882E. In the case of MIL-STD-882 System Safety Programs, the Preliminary Hazard Analysis is the first "analysis" performed. Notice the word "analysis". The Preliminary Hazard Analysis is not the first safety "document" produced. It is preceded by documents which sometimes includes a Preliminary Hazard List (PHL). The Preliminary Hazard Analysis identifies safety-critical areas, provides an initial assessment of hazards, and identifies requisite hazard controls and follow-on actions.
The Preliminary Hazard Analysis is used to obtain an initial risk assessment of the system hazards. It is based on best available data, including accident/incident data, from similar systems and other lessons learned. Hazards, associated with the proposed design or function, are evaluated for hazard severity, hazard probability, and operational constraints. Safety provisions and alternatives, needed to eliminate hazards or to reduce their associated risk to an acceptable level are included in the Preliminary Hazard Analysis.
To this day, there are contracts that erroneously call for a Preliminary Hazard Analysis as a final deliverable. As its name denotes, the Preliminary Hazard Analysis is a temporary document. It is superceded by the Hazard Log (HL).
There are very few useful published guidelines for producing a Preliminary Hazard Analysis, which is the precursor to all subsequent safety analyses. We have seen and continue to see absolutely horrible PHAs. So, beyond "brainstorming", how should the process be conducted? Read on.
HCRQ can teach you how to perform better, faster PHAs using Optimal Hazard Identification (OHI) (based on advice received from psychologists) either at our
HCRQ has been tasked, on more than a few occasions, to coordinate Preliminary Hazard Analysis sessions even in cases where we know very little about the system being developed. This is a testimony to the effectiveness of the OHI process. Get ready to save money. Remember how costly these multi-disciplinary meetings are? It is often difficult even to form these groups.
The Preliminary Hazard Analysis is not the only hazard identification technique. In the case of SAE ARP4761, Functional Hazard Assessment (FHA) is the first analysis performed (by the way FHA is not equivalent to PHA). Some people use HAZOP or, believe it or not, FMEA techniques for this purpose.