The Human Factors Funnel Model – Another Window on Error Causation

Human Factors Funnel Model

This is a post by guest author Dr. Robert (Bob) Baron. Bob was asked to contribute to our business aviation blog because of his expertise in aviation safety and human factors. Any thoughts expressed below are entirely Bob’s and do not necessarily reflect the views of Universal Weather and Aviation, Inc.

Understanding the nature of error causation is important for any organization, and this can be particularly critical within the general aviation (GA) world. Human Factors Funnel Model (HFFM) is a conceptual framework meant to provide another useful window on error causation. Here’s a brief synopsis of the HFFM concept.

The article below is meant to be an introduction to HFFM. The full article from Dr. Bob Baron can be found here.

1. What HFFM is

Over the past few decades, there’s been a noticeable shift in the error causation paradigm. Lately, there’s been a focus on the organization itself being complicit in the active errors that individuals commit. Responsibility in the event of an incident cannot, however, be relegated solely to the person who committed the “active error” or to upper levels of management who are guiding the organization. The HFFM conceptual framework proposes that there are many component parts throughout an organization that can impact error causation and accidents.

2. Why HFFM is referred to as a “funnel”

In its broadest concept, the HFFM is analogous to how a funnel works (see below). The opening is fairly wide and this depicts the Atmosphere (organization). As the funnel tapers down, there are various individual factors that mix together. The combined influences of the Atmosphere and individual factors then flow to Outcomes (or what pours out the bottom). Outcomes are color coded in red and green. Red indicates unsuccessful outcomes while green indicates successful outcomes.

Human Factors Funnel Model

3. Why “Atmosphere” is at the top of the funnel

The Atmosphere (or organization) is at the top of the funnel as the organization and corporate culture has an overarching effect on the rest of the funnel elements. Organizational culture can and will affect the overall performance of employees by setting precedents and behavior. Some of the most dangerous companywide negative norms may be propagated by the highest levels of an organization.

4. What the other four elements in the funnel are

Attributes can best be described as the innate qualities a person possesses as part of his or her personality. These attitudes are more or less ingrained in a person, resistant to change, and can have a significant impact on individual or team performance. Attitudes can be described as the way someone feels about someone or something, which in turn may guide that person’s behavior. Unlike Attributes, Attitudes are a bit more dynamic and easier to change. A change in attitudes can result in something positive or negative occurring. Decisions are the choices we make based on multiple alternative solutions. Poor decision skills continue to be cited in a multitude of aircraft accidents. Now that all components have mixed together in the funnel, a person’s actions at this point will set the stage for final Outcomes.

5. Why this is important

HFFM does an effective job in depicting a range of error factors that may cause an accident, ranging from the captain’s personality and pilot training issues to company policies and events that occur the day of the accident. When reviewing an accident using HFFM conceptual format, it can become clearer where individual and organizational deficiencies were occurring.

6. Case examples using HFFM

The Continental Express Flight 2574 accident in 1991, where a crash occurred on approach to Houston Intercontinental (KIAH), exemplified a true organizational failure from the maintenance perspective and was a quintessential organizational failure. The 2004 Gulfstream III accident on approach to Houston Hobby (KHOU), on the other hand, exemplified an individual failure that had no discernible connection to a broad organizational failure. The Kenya Airways Flight 507 accident at Douala, Cameroon (FKKD), where pilots lost control and the aircraft entered an unrecoverable spiral dive, also provides a good fit to demonstrate practical applications of HFFM. There were organizational as well as individual factors that significantly contributed to this particular accident.


HFFM is well-suited as an active and proactive investigation model. Based on the mixture of ingredients in the funnel, outcomes will either meet or not meet intended safety objectives. The key here is to focus on the “big picture” in terms of what organizational and/or individual elements may be responsible in error causation so that future unsafe practices and incidents can be avoided.

The above article is meant to provide an intro to HFFM. The full article by Dr. Bob Baron can be found here.


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