Human factors in Complex
Aviation Systems
Cognition and some related errors
The greatest hazard to aircraft is…?
Gravity •
Human •
Role of human in Aviation Accidents
The odds are against doing it right!
• 1 correct
pattern
• 40320
incorrect
patterns
Human Error- Definition
• A human action
with unintended
consequence.
Types of human error
Human error
Unintentional
Mistake
Slip
Intentional
Violation
Intentional error
• Violation
– Is not an error.
– Security issue.
Mistake
• A bad plan
– Wrong formula for OCH calculation.
Slip
• A good plan, poorly executed.
– 26 instead of 62
Active and latent errors
Latent error
Active error
• An error occurred before
operation in system and
materialized by operation.
• Actions or inactions of
operational pesonnel.
Main causes of human error
• Dirty Dozen
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complacency
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Lack of awareness
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Distraction
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Memory- Basic Components
• Many models of human memory have been
developed by cognitive psychologists.
• Most of models agree on three basic
components:
Sensory
Memory
(Register)
Short-term
Memory
Long-term
Memory
Different types of Memory
• Sensory Memory
– Each sensory system has a corresponding sensory memory.
– Stores and transforms the stimuli into a form that can be processed.
• Short-term Memory
– STM receives, holds and processes information from sensory memory
– Processing in STM is necessary before transferring to LTM.
– Retrieves information from LTM.
• Long-term Memory
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Receives information from STM and stores it indefinitely.
Unlimited capacity for practical purposes.
Containing all of our life experiences.
Our life data base
Memory - Basic Processes
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Encoding
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Maintenance
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Sensory stimuli enter sensory memory
"attended to" information is encoded into a form that can be processed by short-term memory.
Information that is not attended to, decays or is "overwritten" by new incoming stimuli.
Short-term memory has limited storage capacity.
Information entering short-term memory "decays" after about 12 to 30 seconds unless it is "rehearsed" or
otherwise consciously attended to and encoded for transfer into long-term memory.
Retrieval
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Information that is stored in long-term memory is retrieved by short-term memory to support recall and
recognition.
Some theorists believe that long-term memory decays overtime, while others believe that memories are still
encoded but the retrieval mechanisms for them have been lost.
Sensory
register
STM
LTM
Information Processing
• Wickens’ Model
Perception
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We do not experience reality
exactly as it exists, but as our
experience and memories
cause us to perceive it
Our perception involves more
than the receipt of sensory
information.
We must attend to, select,
organize, and interpret this
information in order to
meaningfully recognize objects
and events in our environment.
Our prior experience and
knowledge, emotional state,
and value system (including
prejudices) determine our
perceptions.
Attention
• Our cognitive processing
begins with selecting an
event
• The event may be
internally generated
(thought) or initiated by
internal or external
stimuli.
• Given the great number
of stimuli impending on
our sensory systems at
any moment in time, we
must select events or
• Our attention resources
are limited.
Attention Control
• Top-Down
• Attention control is
under conscious
direction, using
information residing in
memory stores.
• Bottom-Up
• Attention is captured
by external stimuli,
usually unexpected
events.
Automatic Processing
• Information can also be processed with little or no allocation of
attention resources.
• When skills are learned to the point of automaticity, the load on
working memory typically is reduced by 90%.
• If one is "used to" a specific position and means of activation of a
control, moving that control or changing its means of activation could
result in the loss of critical seconds in response to an emergency.
• Complacency in automated tasks!
STM
• Our working memory
• Our cognition workbench
• Capacity
– Very limited
– Considered a "bottleneck" in human information
processing.
– The number of units that can be processed at any one time
as 7 + 2
• Duration
– About 15 to 30 seconds
– It can be indefinite if one continues to concentrate on,
attend to, and rehearse the information in its store.
Exercise
• Memorize
Exercise
Exercise
• Remember
STM improvement
• Rehearsal
– An example is repeating a phone number or a person's name
until it is "memorized."
– When such rehearsal is being performed no other new
information can enter.
• As a result, while you are repeating the name of the first person to
whom you were introduced, you may "miss" the name of the second
person.
• Chunking
– To assemble items to be learned into "chunks." That is, group
the material to be learned so that it fits within the 7 + 2 item
capacity.
– Research has indicated that "experts" may not have larger
memories, but use larger "chunks" than novices.
STM aid tools
• Acronyms
• Acrostics/Sentences
– Richard of York Gave Battle in Vain (Red, Yellow, Green, Blue, Violet).
• Rhymes/Songs
– "ABC Song,"
– "Aviate, navigate, communicate.“
• Everyday Memory Tools
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Shopping lists,
Writing reminder notes to oneself,
Using appointment diaries or calendars,
Using clocks and timers,
Placing objects in a specific place as a reminder,
Asking someone to remind you.
• Checklists
Two causes of human error
• Distraction
– A distraction while performing task may disrupt the
procedure. When work resumes, it is possible that the
human skips over a detail that needs attention.
• It is estimated that 15 percent of maintenance related errors are
caused by distractions.
• Lack of Awareness
– A failure to recognize all the consequences of an action or
lack of foresight.
• In aviation, it is not unusual to perform the same tasks repeatedly.
After completing the same task multiple times, it is easy for
human to become less vigilant and develop a lack of awareness for
what they are doing and what is around them.
Comments?
Questions?