Defining features of QHRA

Like the Human Error Assessment and Reduction Technique (HEART), QHRA requires the analyst to select generic probabilities from tables, matching the reference task to examples. But QHRA is unique in applying a 3-pass approach to analysing human reliability. The underlying rationale for the phased approach is that analysts are able to allocate time and effort more efficiently by assessing in detail only those systems shown early in the analysis to be hazardous. By including dependency and error recovery, the technique attempts to move closer the reality of ship operating environments where subsystems are often closely linked and where the probability of error recovery varies considerably.