The Human Error Template: Increased Safety & Reduced Risks in SOPs


  • The HTA was applied to the SOPs for Final Approach to Parking Ramp and received the following evaluation:
Table 1: Level Hierarchy for Landing
Level Type Number Expected E.g.
Level 1 Main Goal 1 IDF Landing Safely
Level 2 Sub-Goal 11 Stop Aircraft at Check Zone
Level 3 Sub-Goal 28 Check After Landed
Level 4 Sub-Goal 16 Navigation Equipment Off
Level 5 Sub-Goal 6 TACAN Off
  • The findings showed that the main goal of a safe landing would not be realised without the completion of the 61 sub-goals found in level 2, 3, 4 & 5

  • The evaluation also identified 43 action items whose performance represented an activity required for a safety reason
  • These 43 action items were then further evaluated using the HET analysis to identify the error likelihood (very low, low, medium, high, very high) and flight safety criticality (very low, low, medium, high, very high) of 12 basic error modes being committed by the pilots on landing:
    • Failure to Execute
    • Task Execution Incomplete
    • Task Executed in Wrong Direction
    • Wrong Task Executed
    • Task Repeated
    • Task Executed on the Wrong Interface Element
    • Task Executed Too Early
    • Task Executed Too Late
    • Task Executed Too Much
    • Task Executed Too Little
    • Misread Information
  • Overall, the restricted time allowed to execute these tasks increased the workload and opportunity for incorrect estimates or executions
  • To effectually thwart the incidence of human errors, action items that scored highly for error likelihood and flight safety criticality were identified as requiring more specific training, a redesign of hardware/software and/or modifications to the SOPs.


Research approach

The research approach for Li, Harris, Hsu & Li (2009) was to apply the Hierarchical Task Analysis (HTA) and the Human Error Template (HET) analysis to evaluate the pilot interface and current SOPs of the Israeli Defence Force (IDF) and contribute towards safer pilot training, more efficient standard operating procedures (SOPs), and greater cognitive ergonomic considerations in hardware and software design


The HET analyses development required knowledge of established IDF SOPs, flight operations, safety management, and aviation human factors. The expert team of six participants organized for this study comprised of:

  • Three pilots, with over 2000 flying hours,
  • Two Researchers in Aviation Safety, and
  • One Expert in Aviation Human Factors


  • An HTA was applied to the SOPs and final approach to parking ramp de-brief
  • The HET analysis was performed to the lowest level tasks in the HTA to spot possible error modes
  • Each participant pilot is required to complete up to 1,548 data cells (Li et al., 2009), for the HET analysis, comprising 12 basic error modes and 3 variables

Data analysis

  • The HTA, according to Li et al. (2009), is the most popular and the most widely used Human Factors (HF) method for task analysis
  • The HTA identified a hierarchy of goals, sub-goals, operations and plans and produced in a highly detailed task description that was subsequently further analysed by the HET analysis developed for this study by the assembled expert team

Generalization potential

  • The study demonstrated the application of HTA and HET of (1) identifying design-induced human errors, and (2) being an applicable method of error prediction for flight safety
  • The analyses can be applied to other aviation operations albeit with an appropriate team of experts to develop the HET analysis


Li, W-C., Harris, D., Hsu, Y-L., Li, L-W. (2009) The Application of Human Error Template (HET) for Redesigning Standard Operational Procedures in Aviation Operations. In D. Harris, (Ed.), Engineering Psychology and Cognitive Ergonomics (pp. 600-605). Oklahoma, USA: Springer Verlag.

Want to know more?

Hierarchical Task Analysis
More information on the HTA by Stanton, N.A.
Human Error Template
More Information on the HET analysis by Stanton, et al., (2006)

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