Human Factors Analysis and Classification System¶
Classify an operational accident through four ordered causal strata— organizational influences, unsafe supervision, preconditions for unsafe acts, and unsafe acts—so investigation climbs past the visible operator error and routes intervention to the layer that generated it.
Core Idea¶
The Human Factors Analysis and Classification System (HFACS) is an accident-analysis framework that classifies contributing conditions into four causally ordered layers: organizational influences, unsafe supervision, preconditions for unsafe acts, and unsafe acts. It directs inquiry upward from visible operator behavior toward latent system conditions.
The canonical identity is narrower than the phrase’s everyday use. A case is coded across the four-layer taxonomy, cross-level pathways are traced, and intervention responsibility is allocated to the level capable of changing the generating condition. The framework's value lies in disciplined classification, not merely the slogan “systems matter.”
How would you explain it like I'm…
Look Up the Ladder
When something goes wrong, like a spilled tray in a lunchroom, it's easy to blame just the kid holding it. This way of checking also asks: Was the kid tired or rushed? Was a grown-up watching? Did the school set things up badly? It sorts the reasons into four shelves, from the kid all the way up to the people in charge.
The Four-Layer Accident Ladder
The Human Factors Analysis and Classification System (HFACS) helps investigators understand accidents. It sorts the causes into four layers:
- the mistake someone made;
- the conditions that made the mistake likely, like being tired or confused;
- how the person was supervised;
- decisions made by the whole organization.
Investigators start with what the worker did and climb up the layers to find hidden problems. Then they fix things at the layer that can actually change the cause.
Four-Layer Accident Taxonomy
The Human Factors Analysis and Classification System (HFACS) is an accident-analysis framework with four causally ordered layers. From bottom to top they are unsafe acts, preconditions for unsafe acts, unsafe supervision, and organizational influences. Investigators begin with the visible operator error and trace upward to latent conditions further back in the system. Each contributing factor in a case is coded into the taxonomy, and links between levels are mapped. Responsibility for fixing things is assigned to whichever level can change the condition that produced the problem. What makes HFACS useful is this disciplined classification, not just the general slogan that 'the system matters'.
The Human Factors Analysis and Classification System (HFACS) classifies an accident's contributing conditions into four hierarchically and causally ordered tiers. These are organizational influences, unsafe supervision, preconditions for unsafe acts, and unsafe acts. Analysis begins with observable operator behavior and proceeds upward toward latent conditions embedded in supervision and organizational practice. The canonical procedure has three steps. First, each contributing factor of a case is coded within the four-layer taxonomy. Second, cross-level causal pathways are traced. Third, responsibility for intervention is allocated to the level that can alter the generating condition. This is narrower than casual use of the phrase to mean any systems-thinking approach. What makes HFACS useful is the structured classification and pathway tracing, which supports consistent comparison across cases.
Structural Signature¶
- It is a whole accident-investigation taxonomy, not one causal stratum.
- Its four levels are ordered from distal organizational decisions through supervision and immediate operator state to the sharp-end act.
- Findings are assigned to layers without treating adjacency as taxonomic subsumption.
- The upward investigative climb has a defined top at organizational influences.
- Remedies are layer-indexed, so a correction aimed at the wrong stratum can leave the causal generator intact.
- It refines Reason's layered-defense model for human and organizational accident causation.
What It Is Not¶
Swiss-cheese models describe aligned defensive failures without supplying the same coding taxonomy. Root-cause analysis is a broader family. Unsafe Supervision is one HFACS stratum, not the entire framework. Human error is an outcome category, not a multilevel classifier.
- The Swiss-cheese model in general, which does not require the four HFACS levels or their sub-taxonomies.
- A generic root-cause method with no fixed ordered strata.
- A claim that every accident must contain a nonempty finding in every layer.
Scope of Application¶
Aviation, medicine, mining, and maritime safety all use or adapt HFACS, but they import the same safety-science framework. Stripping accident investigation and its named strata leaves generic multilevel causal analysis.
A shared label or downstream consequence is insufficient; the load-bearing roles must survive.
Clarity¶
Human Factors Analysis and Classification System separates a specific relation from neighboring ideas that can produce similar observations. Swiss-cheese models describe aligned defensive failures without supplying the same coding taxonomy. Root-cause analysis is a broader family. Unsafe Supervision is one HFACS stratum, not the entire framework. Human error is an outcome category, not a multilevel classifier.
Manages Complexity¶
The abstraction compresses recurring cases into one inspectable model. An analyst can track the structural roles, compare mechanisms, and locate exactly which missing commitment invalidates an analogy.
Abstract Reasoning¶
Identify the candidate roles, test the defining relation, then challenge the nearest boundary case. A report that simply blames both “management” and “the pilot” without coding causal pathways through the four layers is not HFACS analysis.
Knowledge Transfer¶
Aviation, medicine, mining, and maritime safety all use or adapt HFACS, but they import the same safety-science framework. Stripping accident investigation and its named strata leaves generic multilevel causal analysis. Transfer is warranted only when the same causal, formal, or relational work survives.
Examples¶
Qualifying pattern. The Human Factors Analysis and Classification System (HFACS) is an accident-analysis framework that classifies contributing conditions into four causally ordered layers: organizational influences, unsafe supervision, preconditions for unsafe acts, and unsafe acts. It directs inquiry upward from visible operator behavior toward latent system conditions.
Boundary case. A report that simply blames both “management” and “the pilot” without coding causal pathways through the four layers is not HFACS analysis.
Structural Tensions¶
T1 — Reach versus identity inflation. Broad use is valuable only while every defining role survives.
T2 — Observation versus mechanism. Similar outcomes can arise from neighboring mechanisms, so classification follows the relation and its counterfactual rather than appearance.
Structural Core vs. Domain Accent¶
Aviation, medicine, mining, and maritime safety all use or adapt HFACS, but they import the same safety-science framework. Stripping accident investigation and its named strata leaves generic multilevel causal analysis. The transferable residue is thinner than the named mechanism, whose domain vocabulary and causal apparatus remain constitutive.
Relationships to Other Abstractions¶
Current abstraction Human Factors Analysis and Classification System Domain-specific
Parents (5) — outgoing typed relations
-
Human Factors Analysis and Classification System includes Active Failure Domain-specific
Active failure supplies the sharp-end unsafe-act constituent stratum of the staged HFACS whole.Remove the sharp-end act stratum and the taxonomy has no visible event whose upstream causal layers it was built to reclassify and trace.
-
Human Factors Analysis and Classification System includes Organizational Influence Failure Domain-specific
Organizational influence failure is the apex constituent stratum of HFACS.Remove the organizational-influence apex and HFACS loses its defined top and its resource, climate, and process intervention layer.
-
Human Factors Analysis and Classification System includes Precondition for Unsafe Act Domain-specific
Preconditions for unsafe acts are the third constituent stratum of HFACS.Remove the precondition stratum and HFACS can no longer separate the operator's immediate probability-shifting state from the act itself.
-
Human Factors Analysis and Classification System includes Unsafe Supervision Domain-specific
Unsafe supervision is the second constituent stratum of HFACS.Remove unsafe supervision and the framework jumps directly from organization-wide decisions to operator state, erasing its supervisory transmission layer.
-
Human Factors Analysis and Classification System is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) Prime
HFACS is the human-and-organizational accident-investigation form of the Swiss-cheese model, adding a fixed four-level taxonomy and layer-indexed remedies.Remove HFACS, aviation mishap investigation, organizational influence, unsafe supervision, operator precondition slots, unsafe-act taxonomy, and layer-specific countermeasures. A hazard penetrates imperfect layered defenses through aligned active and latent holes, and analysis traces the complete trajectory rather than stopping at one visible failure.
Hierarchy paths (102) — routes to 11 parentless roots
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Conjunctive Path Activation → presupposes, typical Causality → is a kind of Dependency
Show alternative paths (101)
- Human Factors Analysis and Classification System → includes Unsafe Supervision
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → is a decomposition of Context
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Self Checking
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Conjunctive Path Activation → presupposes, typical Causality → is a kind of Dependency
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Self Checking
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Self Checking
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Self Checking
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Conjunctive Path Activation → presupposes, typical Causality → is a kind of Dependency
Show 93 more paths
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Conjunctive Path Activation → presupposes, typical Causality → is a kind of Dependency
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a kind of Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Optimization
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Self Checking
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Self Checking
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Self Checking
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → presupposes Heavy-Tailed Distributions
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a kind of Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a kind of Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a kind of Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Optimization
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Optimization
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Optimization
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a kind of Recurrence
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Self Checking
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a kind of Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → presupposes Heavy-Tailed Distributions
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → presupposes Heavy-Tailed Distributions
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → presupposes Heavy-Tailed Distributions
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a kind of Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a kind of Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a kind of Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Optimization
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Optimization
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Optimization
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a kind of Recurrence
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a kind of Recurrence
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a kind of Recurrence
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a kind of Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a kind of Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a kind of Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → presupposes Heavy-Tailed Distributions
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → presupposes Heavy-Tailed Distributions
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → presupposes Heavy-Tailed Distributions
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a kind of Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Optimization
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a kind of Recurrence
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a kind of Recurrence
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a kind of Recurrence
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a kind of Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a kind of Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a kind of Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Trade-offs → presupposes Constraint
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → presupposes Heavy-Tailed Distributions
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a kind of Recurrence
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a kind of Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Trade-offs → presupposes Constraint
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Trade-offs → presupposes Constraint
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Trade-offs → presupposes Constraint
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Mobilization → presupposes Latent Realizable Capacity
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a decomposition of State and State Transition → includes Phase Space
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → presupposes Problem Representation → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Trade-offs → presupposes Constraint
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Trade-offs → presupposes Constraint
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Trade-offs → presupposes Constraint
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a decomposition of State and State Transition → includes Phase Space
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a decomposition of State and State Transition → includes Phase Space
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a decomposition of State and State Transition → includes Phase Space
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → presupposes Problem Representation → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → presupposes Problem Representation → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → is a decomposition of Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → presupposes Problem Representation → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Trade-offs → presupposes Constraint
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Reserve → is a decomposition of Economy Of Force → is a kind of Allocation → presupposes Scarcity → is a decomposition of Constraint
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a decomposition of State and State Transition → includes Phase Space
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a decomposition of State and State Transition → includes Phase Space
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a decomposition of State and State Transition → includes Phase Space
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → presupposes Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → presupposes Problem Representation → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Organizational Influence Failure → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → presupposes Problem Representation → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Precondition for Unsafe Act → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → presupposes Problem Representation → is a kind of Representation → presupposes Abstraction
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → is a decomposition of State and State Transition → includes Phase Space
- Human Factors Analysis and Classification System → includes Active Failure → presupposes Latent Condition → presupposes Swiss Cheese Model (Layered Defense with Aligning Holes) → is a kind of Defense In Depth → is a kind of, typical Redundancy → is a decomposition of Two-Store Architecture → presupposes, typical Caching → presupposes Locality Of Reference → is a decomposition of Spatial Indexing → is a kind of Search and Retrieval → presupposes Problem Space → presupposes Problem Representation → is a kind of Representation → presupposes Abstraction
Neighborhood in Abstraction Space¶
Human Factors Analysis and Classification System sits in a sparse region of the domain-specific corpus (99th percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.
Family — Unclustered & Miscellaneous (2769 abstractions)
Nearest neighbors
- Organizational Influence Failure — 0.77
- HAZOP Guideword Miss — 0.76
- Goal structuring notation — 0.75
- Bradford Hill criteria — 0.74
- Internal validity — 0.73
Computed from structural-signature embeddings · 2026-10-25
Not to Be Confused With¶
Swiss-cheese models describe aligned defensive failures without supplying the same coding taxonomy. Root-cause analysis is a broader family. Unsafe Supervision is one HFACS stratum, not the entire framework. Human error is an outcome category, not a multilevel classifier.
- The Swiss-cheese model in general, which does not require the four HFACS levels or their sub-taxonomies.
- A generic root-cause method with no fixed ordered strata.
- A claim that every accident must contain a nonempty finding in every layer.