Human Factors Case Study - Human Error vs Human Factors Singapore
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Human Factors Case Study - Human Error vs Human Factors
Singapore Airlines Flight 006 Accident
Taipai, Taiwan
October 31, 2000
Excerpt from Human Factors for Process Safety Course
David A. Moore, PE, CSP
President
AcuTech Consulting, Inc.
100 Bush Street, Suite 200
San Francisco, CA 94104
http://www.acutech-consulting.com/training/index.html
SQ006 Incident Overview
October 31, 2000
A multi-fatality incident involving Singapore Airlines
Flight 006 (SQ006) at Taipai’s Chiang Kai-shek Airport
provides a case study in human error caused by human
factors vs individual human error alone
SQ006 crashed into runway barricades and construction
equipment on takeoff resulting in over 83 fatalities of the
159 onboard*
* Photos and information credit: http://www.channelnewsasia.com/sq006/
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SQ006 – Simply Pilot Error?
The ill-fated SQ006 was on the wrong runway before it crashed on
Tuesday night, said Taiwan's chief investigator at a news
conference*
The pilot had been cleared for takeoff on the designated runway
(5-L), but instead departed the aircraft down the wrong runway
(5-R), which was a parallel runway under repair at the time.
The statement by Kay Yong, Taiwan's Aviation Safety Council
managing director, implied that pilot error played a major role in the
crash of the Boeing 747-400, which led to the death of 83 people.
The cause - An obvious case of pilot error alone??
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SQ006 – Review of the Work Situation
What human errors occurred besides the pilot error?
What human factors contributed to the likelihood of the
initiating event?
What human factors contributed to the event sequences
that followed?
Were there opportunities to stop the escalation of a pilot
error to an accident?
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Definition of Human Error
and Human Factors
Before we answer those questions, let’s review the
definition of human factors vs human error
How do you define human error?
How do you define human factors?
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Definiton of Human Error
Human error is defined as “any human action (or lack
thereof) that exceeds some limit of acceptability (I.e., an
out-of-tolerance action) where the limits of human
performance are defined by the system”
From “A Manager’s Guide to Reducing Human Errors, Improving Human Performance in the Chemical Industry, Chemical Manufacturer’s Association,
July 1990.
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Human Error Types
1. Intentional – deliberately commit or omit the prescribed
actions
2. Unintentional – committed or omitted with no prior
thought
From “A Manager’s Guide to Reducing Human Errors, Improving Human Performance in the Chemical Industry, Chemical Manufacturer’s Association,
July 1990.
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Definition of Human Factors
Environmental, organizational, and job factors, and
human and individual characteristics which influence
behavior at work in a way which can affect health and
safety.[1]
[1] Reducing Error and Influencing Behavior, HSG48, HSE (1999).
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Human and Organizational Factors
Human and organizational factors can be related to the
individuals that design, construct, operate, and maintain
the system.[3]
[3] Bea, Holdsworth, and Smith, “Human and Organization Factors in the Safety of Offshore Platforms”, a paper presented at the 1996 International
Workshop on Human Factors in Offshore Operations
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Four Components of Human Factors
The actions or inactions of these individuals are
influenced by four components:
1. The organizations that they work for
2. The procedures (formal, informal, software) they use to
perform their activities
3. The structure and equipment involved in these activities
4. The environments in which the individual conducts
activities.
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SQ006 Accident – 747-400
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Transcript From the Black Box Recording of SQ006
(The recording begins from 18 seconds after 11.15 pm 1515GMT)
11.15.18 ATC (tower) Singapore 6 runway 05 left (5L). Wind 020 (degrees) at 28
(knots). Gust to 50. Clear for take off.
11.15.26 Captain - Clear for take off. Runway 05 left. Singapore 6.
11.16.19 Captain - We can see the runway not so bad. OK., I am going to put it
to high first.
11.16.51 First Officer - 80 knots.
11.16.52 Captain - OK, my control.
11.17.08 First Officer - V1*.
11.17.12 Captain - (Expletive). Something there.
11.17.13 Banging sound.
11.17.14 Captain - Unintelligible words. Followed by a series of crashing sounds.
11.17.18 Recording stopped. -
*(Speed of 142 knots/hour, at which take-off can no longer be aborted)
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Taipei Airport Runway Layout
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SQ006 Accident – Taipai
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SQ006 Accident – Taipai
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SQ006 Accident – Taipai
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SQ006 Accident – Taipai
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SQ006 Accident – Runway Debris
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SQ006 Accident – Debris Layout
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SQ006 Incident Overview –
Human Factors in Design
The closed runway, number 05R, did not have a
barricade that made it impossible for an aircraft to take
the wrong runway
Runway 05R was not blocked off by barriers because
part of the strip was used by landing planes to taxi back
to the terminal.
Runways which are closed are normally not lit up to
make it clear they are not in use. But this was reported
to not be the case at Chiang Kai-shek airport, where a
single switch controls green lights on the common
taxiway to both runways and down the middle of 05R.
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SQ006 Incident Overview –
Human Factors in Design
The pilot confirmed twice to the control tower that he
was on the correct runway.
But officials there did not know the plane had actually
gone on to the wrong runway because the airport does
not have ground radar and the plane was out of sight at
the time of its takeoff.
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HEPs Can Be Most Effectively
Reduced in Work Situation Redesign
Improvement Resulting decrease in HEPs
(Factors)
– Good human factors – 2-10x
engineering practices in
design of controls,
displays, and equipment.
– Redesign of displays or – Over 10x
controls that violate strong
population stereotypes
Kletz, T. A., and Whitaker, G. D., Human Error and Plant Operation, ICI, 1973
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SQ006 Incident –
Possible Sources of Human Error
Pilot –
Error in operation – took wrong runway despite proper
instructions?
Controller –
Error in observation – did not track aircraft position (caused by
inability to do so - no ground radar)?
Construction workers and/or airport management –
Error in maintenance – did not provide sufficient
warning/barricades at the most effective point – at the entrance
to the runway under repair?
Designer –
Error in design – inactive runways did not have distinct warning
lights to identify closed status?
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SQ006 Incident – Possible Sources of
Human Error (cont’d)
Airport management –
Error in operation – allowed the aircraft to take off despite
weather conditions?
Left construction equipment and barricades on the runway?
Did not provide ground observer?
Did not provide adequate signage or barricade?
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SQ006 Incident – Possible
Performance Shaping Factors
Weather – storm conditions with rain, high winds, limited
visibility?
Time of day – Nighttime with reduced visibility due to storm
and darkness?
Timing – Pressure to takeoff within time slot allocated?
Stress – Pilot of 747 with responsibility for 157+ passengers
and crew under takeoff conditions; controllers with multiple
responsibilities?
Limited information – controllers could not track the aircraft
while on the ground; pilot could not see obstacles and had no
feedback on his error?
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Performance Shaping Factors (PSF)
Internal PSF’s:
Training/Skill
Practice/Experience
Knowledge of Required Performance Standards
Stress
Intelligence
Motivation
Personality
Emotional State
Physical Condition/Health
Culture
From “A Manager’s Guide to Reducing Human Errors, Improving Human Performance in the Chemical Industry, Chemical Manufacturer’s Association, July 1990.
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Performance Shaping Factors (PSF)
External PSF’s – Situational Characteristics:
Architectural features
Environment (noise, heat, humidity, lighting, etc.)
Work hours and schedule
Availability of equipment
Staffing levels
Actions by Supervisors
Plant policies
From “A Manager’s Guide to Reducing Human Errors, Improving Human Performance in the Chemical Industry, Chemical Manufacturer’s
Association, July 1990.
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Performance Shaping Factors (PSF)
External PSF’s – Task, Equipment, and Procedural
Characteristics:
Procedures (written or unwritten)
Communications (written or oral)
Work methods
Frequency/repetitiveness
Physical requirements
Complexity (information overload)
Feedback
Hardware interface factors (design, job aids, equipment)
Task criticality
From “A Manager’s Guide to Reducing Human Errors, Improving Human Performance in the Chemical Industry, Chemical Manufacturer’s Association, July
1990.
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Performance Shaping Factors (PSF)
Physiological/Psychiological Stressors:
Fatigue
Climate extremes
Movement repetition
Sleep deprivation
High task overload
Threats
Negative reinforcement
Lack of rewards, recognition, or benefits
From “A Manager’s Guide to Reducing Human Errors, Improving Human Performance in the Chemical Industry, Chemical Manufacturer’s
Association, July 1990.
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SQ006 – Preventable?
Barricade at entrance to runway?
Radar for tracking aircraft position on the ground?
Improved runway markers and lighting?
Limit operations in poor weather conditions ?
Limit operations near construction areas?
Observer at ground for air traffic control in poor
weather conditions or during construction?
Analysis of work situation and anticipation of errors?
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Human Factors in Process Safety –
Understood it is a problem, but is it
understood?
It is understood that human factors greatly contribute to
the success or failure of process safety programs in the
chemical process industries
But most of industry has not developed special initiatives
to comprehensively address human factors.
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Human Factors – Why not a focus?
Human factors has seemed
too ambiguous or subjective?
too involved and comprehensive?
potential for high cost for redesign?
too difficult to change human behavior?
unnecessary – Murphy’s Law?
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Opportunity Missed?
Industry may not have fully addressed what has often
been characterized as the area that should receive the
most attention
There are ripe opportunities for risk reduction.
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How to Reduce Human Error
1. Incorporate human factors into inherently safer design
practices, management practices, and into
improvements in the work environment
2. Ensure human factors are imbedded into the culture
3. The key objective - to reduce the number and
likelihood of situations to produce error.
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Human Factors Program Elements
1. Written human factors policy and commitment
2. Employee knowledge and involvement
3. Training on human factors and incorporating human
factors in all training activities
4. Incorporating human factors into hazards analysis
5. Human factors in MOC – organizational change
6. Incident investigation and human factors root cause
assessment
7. Consideration of human factors in written work
procedures
8. Auditing of the human factors program performance
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Objective of a Human Factors Program
To develop an employee-based system that
ensures that human factors considerations are
pervasive in the organization in order to reduce
error-likely situations and incidents caused by
human factors issues.
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Error-Likely Situations
Inadequate, inoperative, or misleading instrumentation
Inadequate labeling
Poor lighting
Poor human-equipment layout and interface
Time pressures for performance
No opportunities to recover from errors
Inadequate physical restrictions
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Reducing Human Error by
Improving the Design
A formal PHA with an emphasis on human factors
should identify the key error-likely situations
Hazard identification is the key to program success
Qualified and trained teams are normally adept at
developing practical solutions to reduce risk
Solutions need to be evaluated further beyond the PHA
sessions
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Reducing Human Error and the
Potential of Human Errors
Emphasize prevention through design, policy,
procedures, training
Always provide for human error despite prevention
efforts
Provide multiple means of warning of error in the early
stages of the event sequence
Provide means of stopping an error before it evolves
Design with layers of defense that control error
outcomes
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Resource for Further Information
www.acusafe.com
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This presentation is an excerpt from AcuTech’s
2-day Human Factors for Process Safety Course.
To attend this course and for training on a complete
range of Process Safety and Risk Management topics,
contact AcuTech at:
Mr. Jeremy Foutch
Manager
AcuTech Training Institute
100 Bush Street, Suite 200
San Francisco, CA 94104
jfoutch@acutech-consulting.com
http://www.acutech-consulting.com/training/index.html
Note: The opinions in this course are those of the author and do not represent an opinion on the causes of the actual
incident. They are presented as an educational example only. The authors do not make any warranty, expressed or
implied, or assume any liability or responsibility for any use, or the results of such use, of this information. These
slides are protected by copyright, with AcuTech Consulting, Inc., owner. These slides may be distributed freely so long
As they are not altered in any way and appropriate credit is given to AcuTech.
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