Ting and Dai (2011) conducted a research to determine if Human Factors Analysis Classification System (HFACS) framework originally developed for US military aviation is also applicable to analyse accident data from the R.O.C Air Force. This article provides a meta-analysis of the original findings.
The HFACS framework consists of four main general headings and each main heading is further broken down to sub-categories as depicted in table 1. The HFACS framework follows the top to bottom hierarchy i.e. accident causation is traced from the organisational level down to operator. Total mishaps of 1,831 were recorded out of a sample of 545 accident reports.
|Table 1: HFACS framework|
|Main category||Sub-category||Human factors mishaps occurrences|
|Organisational Influences||Resource management, Organisational climate, Organisational processes||272 (14.9%)|
|Unsafe supervision||Inadequate supervision,
Planned inappropriate operations,
Failure to correct problem,
|Precondition for unsafe acts||Environmental factors, Condition of operator, Personal factors||570 (31.1%)|
|Unsafe acts of operators||Errors, Violations||752 (41.1%)|
Reported accidents at sub-category level were then statistically tested for association with categories at the organizationally higher levels. A test for association between dependent and independent variables was conducted using Pearson’s chi-square test.
The reliability of the results of this research also depends on the thoroughness of accidents investigation and the completeness of the sampled reports. Secondly, due to the fact that there exists many-to-one mapping of errors and unsafe acts (Reason, 1990) in Human Factors, mapping is then open to subjectivity. This is evident when assigning dependent variables to independent variables.
The study is a descriptive research to determine if the HFACS framework originally developed for United States military aviation by Wiegmann and Shappell in 2003 is also applicable for the analysis of accidents data from R.O.C Air Force.
A sample data used for the study originates from the 545 accidents reports. The accidents occurred between 1978 and 2008 in R.O.C Air Force. The majority of the sample is from class-3 accidents accounting for 240 accidents. The second largest accidents are class-1 by 219 accidents and followed by class-2 accounting for 78 accidents.
Ting and Dai (2011) used an already existing system to analyse human factors in R.O.C Air Force. The system is called Human Factors Analysis and Classification System (HFACS). The system was established by Wiegmann and Shappell in 2003 which is based on Reason’s model published in 1990.
The four main categories of HFACS in this article are treated as independent variables. Dependent variables are of nominal value and can only take one of two possibilities, existence or non-existence of the activity. All sub-category members of HFACS are dependent variables.
The four Independent variables are:
- Inadequate supervision
- Planned inappropriate operations
- Failed to correct problem
- Supervisory violations
- Environmental factors
- Condition of operator
- Personal factors
Preconditions for unsafe acts
Unsafe acts of operators
- None assigned
The original authors of the article performed chi-square statistical analysis to test the association between variables. The Guttmann and Krustall analysis was also performed in order to calculate proportional reduction in error. The interpretation of the chi-square analysis is also included.