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Integrating Threat & Error Mgmt

by Darren Smith, CFII/MEI
General Aviation Human Factors, May, 2007
Navigation:  Fundamentals of CRM | Resolving Conflict | Workload Management | Checklist Usage | Briefings & Callouts | Training CRM | Threats to Safety | Intro to TEM | Error Management | Integrating Threat & Error Management  | TEM Countermeasures | FOTA | What are you doing over there? | New Captain Series

TEM Series:  Threats to Safety | Unsafe Acts | Intro to TEM | Error Management | Integrating TEM | Countermeasures

In the first article of this series, you learned about threats to safety during any given flight.  Things such as pilot skill, schedule, equipment, distraction, miscommunication with ATC, and weather are all threats to the safe outcome of your flight.

The whole purpose of the preflight planning we do is to avoid those threats to flight safety.  As expected, sometimes things don't go as planned and those threats slip through.  When we fail to avoid those threats, we're spending our time managing the threat so it doesn't become an error. 

In the second article of this series, you learned the basics of TEM, the TEM Model, and learned the differences between each of the stages.

In the third article of this series, you learned about managing errors.  You discovered that error management is a game of resisting or preventing error and for those that slip past you, resolving or mitigating error.
  • Resisting or preventing error.
  • Resolving or mitigating error.
To the above right is a model for integrating threat and error management (Source: ICAO).  This is an expanded view of the model we’ve been using over these last few articles.  It shows the path from threat to aircraft accident or "end state." The purpose of this article in the series is to integrate what you know about threats and errors and how they lead to undesired aircraft states.

Undesired aircraft states are defined as "operational conditions where an unintended situation results in a reduction in margins of safety". They are a result of ineffective threat and error management This reduced margin of safety is considered the last stage before an incident or accident occurs. The undesired aircraft state must be managed.

Examples of undesired aircraft states include: off altitude, off airspeed, off course, and the wrong place at the wrong time.  Managed effectively, pilots can restore margins of safety or if mismanaged could likely create additional error, an incident, or accident.  Unfortunately pilots must manage the undesired aircraft state often times ignoring new threats and errors.  As you’ll see in the following case study, the error chain led to loss of critical safety margins and ultimately an aircraft accident.

Case Study

I interviewed a gentleman who recently had a gear-up accident in his Cessna 210.  He described a sequence of events that led him to scene of the accident.  In spite of the training, in spite of the gear horn warning, and in spite of the fact he had another experienced pilot riding with him, he still failed to put the gear down prior to landing.  Here's why:

The Threats Jim was managing:
  • Jim was coming home from a 3 hour flight - fighting fatigue & his decreasing skills.
  • Upon arriving at his home airport, ATC switched runways on him at the last minute. This flustered him because he had planned and briefed landing on the North-South runway and now needed to land on the East-West runway.  He is now setting up to landing on the new runway assigned.
  • He was concerned that his crosswind skills were not up to par.  He had an opportunity to practice crosswind landings the previous Saturday but chose to go golfing.

The Errors Jim was making:

  • Jim was interrupted during his descent checklist and did not complete it.
  • Jim was surprised by the last minute runway change and did not complete his before landing checklist.
  • Jim was having difficulty making the cross wind correction for the pattern on the first runway.
  • Jim was having difficulty making the cross wind correction for the pattern on the 2nd runway.

How Jim was managing these errors:

  • No attempt was made to completed the descent checklist
  • No attempt was made to completed the before landing checklist
  • Jim was barely managing the errors he was making with the cross wind correction.

The Undesired Aircraft State Jim was experiencing:

  • The aircraft engine was running hotter than normal because the descent checklist had not been completed.
  • The gear was not down because the before landing checklist had not been completed.
  • The flaps were not configured for landing.
  • He wasn't lined up with the runway.

End State:
As a result of these efforts, Jim landed the aircraft on its belly.  A new engine and a new 3 blade prop were on order.  Extensive mechanical work was done fixing the belly.  FAA enforcement action was initiated against Jim.

How do you prevent errors from multiplying and putting you in an undesired aircraft state?  In this situation, two simple words would have given Jim enough time to get everything together and get it right:

Go Around

NEXT:  TEM Countermeasures>>

One also has to wonder, what was that other pilot doing during all that time? Learn about Pilot Monitoring in this article: What are you doing over there?

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