write:Looking at the left side of the first branch we can see that when “over-sights and omissions” result in “system” deficiencies these deficiencies exist in not only the ope

may have degraded performance excessively
or may have required an excessive length of time to implement. In other words
people knew it was going to happen
they just didn’t know when or where.Looking at the left side of the first branch
we can see that when “over-sights and omissions” result in “system” deficiencies
these deficiencies exist in not only the operational system
they also exist in the management system which allowed the operational deficiencies to exist. In other words
when an accident is the result of “oversights and omissions”
the investigation must focus on both the deficiencies in the operational system “AND” the manage-ment deficiencies which allowed the operational deficiencies to exist. While the left hand branch below the oversights and omissions “AND” gate examines “what happened”
the right hand branch examines why it was allowed to hap-pen. Remember that the tree shown in Figure 37-17 represents only the very top levels of a MORT tree. There are over 1
500 potential events to be evalu-ated in a full MORT analysis. From looking at the number of transfer triangles at the top
you can predict that this is going to be a fairly messy analysis before you get to the end.Finally
the use of “LTA” deserves mention. You won’t find any causal factors identified in a MORT analysis. Instead you will find only LTA
which stands for “Less Than Adequate”. When an accident report points out perfor-mance which was “less than adequate”
it is less offensive and harder to defend against
than performance which was “deficient” and a “cause” of the accident. LTA still implies that changes are necessary to improve performance. That term has been picked up and used in several other analysis techniques.Figure 37-17. Upper Levels of a MORT Tree.