Threats & Errors – Defining Threats & Errors

What is a threat?
Anything that requires crew attention and management to maintain safety margins.

Types of threats include:

• Anticipated – threats that are expected by the crew, through planning, research, or even local knowledge. (Glare, Heat, Weather, Cold Batteries)
• Unexpected – threats that suddenly, possibly without any prior symptoms, occur and cannot be reasonably anticipated. (Sudden engine failure)
• Latent – Threats present, but not immediately obvious or noticeable to the crew.  (poor controller ergonomics)

What is an error?

• Actions or inactions that lead to a deviation from intentions or expectations

Errors are defined as flight crew actions or inactions that lead to a deviation from crew or organisational expectations.

These can be:

• Slips – Lack of attention
• Lapses – Memory failure
• Violations – Conscious decision to go against procedure
                         (You may have good or poor intentions)

Note: TEM puts all human failures in one ‘Error’ category to simplify the flow. Usually we wouldn’t categorise a conscious violation as an error!

Effects of an error:

• Reduced safety margins
• Increased probability of adverse outcomes on the ground and during flight

They can be minor:

• Setting wrong flight director mode but quickly recognising and changing.

Or severe:

• Incorrect takeoff configuration

Errors are inevitable, as fallible human beings we will NEVER have a perfect day where we are error free.

1. Procedural – followed procedures but wrong execution

Example)   Lever and switch settings  Wrong Autopilot mode executed 

2. Communication – Misinterpretation or missing information or during an exchange

Example)   Wrong readbacks to ATC  Missed ATC calls 

Wrong course / intentions communicated to another RPAS pilot

3. Proficiency – lack of knowledge error

Example)   Lack of flying proficiency  Lack of knowledge of automation 

Lack of procedural knowledge

4. Operational Decision – discretionary decision not covered by procedures that unnecessarily increases risk

Example)   Over-reliance on automation  Unnecessary low maneuver on approach 

5. Intentional Noncompliance – violations

Example)   Omitted required briefings  Performing checklists from memory

Navigation into adverse weather  

Don’t forget to include intentional non-compliance as an error that we make consciously. It’s the one type of error that you always have to choose to make and can choose not to make.

An undesired aircraft state is:

• A position, condition, or attitude of an aircraft that clearly reduces safety margins.
• It is a result of poor threat and error management by the flight crew.

UAS is defined as a position, condition or attitude of an aircraft that clearly reduces safety margins and is a result of actions by the flight crew.

Merritt & Klinect, 2006

It is the result of poor TEM.

As with an error, a UAS can be managed and recovered from, leading to an inconsequential outcome.

Or, they can result in an incident or accident, if not recovered from.

Some examples of undesired aircraft state:

• Continued Unstable Approach​
• RPAS Pilot Induced A/C Position​
• RPAS Pilot Induced Speed Deviation
• Flying with Low Battery Alert​​

An undesired aircraft state can end in two scenarios:

• Recovery – action is taken to return the aircraft to a safe operating state.
• Incident or Accident – UAS is not correctly detected, understood, or corrective action is not taken in appropriate time.