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1. Classify the task type (GTT, Generic Task Type)
A - Totally familiar, performed at speed with no idea of likely consequences
B - Shift or restore system to new or original state on a single attempt without supervision or procedures
C - Complex task requiring high level of comprehension and skill
D - Fairly routine task performed rapidly or given scant attention
E - Routine highly-practised, rapid task involving relatively low level of skill
F - Restore or shift a system to original or new state following procedures with some checking
G - Completely familiar, well designed, highly practised routine task occurring several times per hour
H - Respond correctly to system command even when there is an augmented or automated supervisory system
M - None of the above
2. Assign Nominal Human Error Probability for each task (r)
A - 0.55
B - 0.26
C - 0.16
D - 0.09
E - 0.02
F - 0.003
G - 0.0004
H - 0.00002
3. Identify Error Producing Conditions and associated factors (EPC_f)
1 – Unfamiliarity
2 – Shortage of Time
3 – Low signal to noise ratio
4 – Ease of information suppression
5 – Ease of information assimilation
6 – Model mismatch (operator / designer)
7 – Reversing unintended actions
8 – Channel capacity overload
9 – Technique unlearning
10 – Transfer of knowledge
11 – Performance standard ambiguity
12 – Mismatch between perceived / real risk
Total effect (f)
1 – x 17
2 – x 11
3 – x 10
4 – x 9
5 – x 8
6 – x 8
7 – x 8
8 – x 6
9 – x 6
10 – x 5.5
11 – x 5
12 – x 4
4 Determine the assessed proportion of Affect (APOA) based on the analysts judgment: Analyst estimates how much the conditions influence the unreliability of the task (p).
5. Calculate HEP (Human Error Probability):
HEP = r * Õ pi*(EPC_fi – 1) + 1
where i is the number of associated EPC factors and
and Õ is the product over all EPC factors and must be smaller than 1 (Nominal Likelihood of Human Error).
6. Consider Error Reduction Measures
Error Reduction Measures can be assigned based on the associated, see Humphrey 88, Williams 88)
This procedure description was primarily informed by following Report:
Eurocontrol (2004). Review of Techniques to support the EATMP Safety Assessment Methodology, V(1), EEC Note No. 01/04
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