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• An error occurred before

operation in system and materialized by operation.

Active error• Actions or inactions of

operational pesonnel.

Main causes of human error• Dirty Dozen

– …– …– …– …– complacency– …– Lack of awareness– …– Distraction– …– …– …

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

MemoryLong-term Memory

Stimuli

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– 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• Encoding

– 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.

• Maintenance – 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

– 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

Stimuli

Retrieval

Maintenance Rehearsal

Information Processing

• Wickens’ Model

Perception• 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– 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?