PRELIMINARY HAZARD ANALYSIS (PHA)
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. Note the word "analysis". The Preliminary Hazard Analysis is not the first safety "document" produced. It is preceded by documents such as the:
- System Safety Program Plan (SSPP),
- Software Safety Program Plan (SwSPP)
- and sometimes the Preliminary Hazard List (PHL).
The Preliminary Hazard Analysis identifies safety-significant areas, provides an initial assessment of hazards, and identifies requisite hazard controls and follow-on actions. Boring, right? Keep reading !!
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 (rare), or reduce their associated risk to an acceptable level, are included in the Preliminary Hazard Analysis. Keep reading !!
To this day, there are contracts that erroneously call for a Preliminary Hazard Analysis as one of the final deliverables. As its name denotes, the Preliminary Hazard Analysis is a temporary document. It is superceded by the Hazard Log (HL). That said, if you are very familiar with the requirements of MIL-STD-882E (versus earlier versions of 882), you are aware of ones that industry found objectionable. Got your curiosity up? Look out using its risk matrix!
There are very few useful published guidelines for producing a Preliminary Hazard Analysis, which is the precursor to subsequent safety analyses. We have seen, and continue to see, absolutely horrible PHAs. So, beyond "brainstorming", how should the process be conducted? What do psychologists say? Read on.
HCRQ (Hunter Austegard) can teach you how to perform better, faster PHAs using Optimal Hazard Identification (OHI) either at our
Join countless others that have flocked to these.
Did you know, for instance, that PHAs can be conducted based on:
- system/subsystem,
- function,
- geographic location,
- hazard type,
- operational phase,
- energy source, or
- other focuses?
In addition, these days it seems that it is problematic organizing group PHA development sessions (e.g., only a very few people {sometimes 1} participate - what do you do in this situation?). This is one example of the types of questions that we are asked at our system safety courses.
HCRQ has been tasked, on many 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 goes without saying that you should know the difference between mitigators and ameliorators.
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; which one is better?; in our system safety course it is interesting when we have civil and military aircraft people present and they weigh FHAs and PHAs).
Some people use HAZOP techniques for this purpose.