human error
DESCRIPTION
This looks interesting, I am writing an article abuot error prediction and prevention in medicine. the last part focuses on errors in aviation that I have no idea about that but the first half worth reading.TRANSCRIPT
HUMAN ERROR
José Luis García-Chico([email protected])San Jose State University
ISE 105 Spring 2006April 24, 2006
“To err is human…”
(Cicero, I century BC)
“…to understand the reasons why humans err is science”
(Hollnagel, 1993)
Jose Luis Garcia-Chico April 24, 2006
What is important to know about human error?
• Human error is in our nature– It might happen everyone, at any time, in any context
• Some errors are preventable through procedures, system design and automation.
– But careful, they may introduce new opportunities of erring.– Emphasis should be put on error tolerant systems: error recovery instead of
erroneous action prevention.
• Human error might not be an accident cause in itself…it might be caused by multiple factors
– Do not only blame last human operator alone.
Jose Luis Garcia-Chico April 24, 2006
Human error in nuclear powers plants
• Three Mile Island (1979)• Due to a failure, temperature in the reactor increased rapidly.
The emergency cooling system should have come into operation but maintenance staff left two valve closed, which blocked flow. Relief valve opened to relief temperature and pressure, but stuck open. Radioactive water pours into containment area and basement for 2 hour.
• Operators failed to detect the stuck open valve. An indicator had been installed to indicate the valve was commanded to shut, not the status of the valve.
• Some little radioactivity was released to the environment.
Jose Luis Garcia-Chico April 24, 2006
Human error in nuclear powers plants• Uberlinguen (2002)• B757 and Tu-154 collided in the German
airspace, under Zurich control. 71 people were killed.
• Only one controller was in charge of two positions during a night shift (two separated displays). Telephone and STCA under maintenance.
• ATC detected late the conflict between both aircraft, and instructed T-154 to descend. The TCAS on board the T-154 and B757 instructed the pilots to climb and descend respectively. The T-154 pilot opted to obey controller orders and began a descent to FL 350 where it collided with the B757. B757 had followed its own TCAS advisory to descend.
Jose Luis Garcia-Chico April 24, 2006
Definition of Human Error
• Error will be taken as a generic term to encompass all those occasions in which a planned sequence of mental or physical activities fails to achieve its intended outcome, and when these failures cannot be attributed to the intervention of some change agency. (Reason, 1990)
• Human error occurrences are defined by the behavior of the total man-task system (Rasmussen, 1987).
• Actions by human operators can fail to achieve their goal in two different ways: the actions can go as planned, but the plan can be inadequate, or the plan can be satisfactory, but the performance can still be deficient (Hollnagel, 1993)
Jose Luis Garcia-Chico April 24, 2006
Human error performance
SENSE/INTERPRET
PLAN/COGNITION
EXECUTION
MISTAKES
SITUATION ASSESSMENT
INTENT OF ACTION
SLIPS
OMMSSION/COMMISION
(Norman, 1983)
Jose Luis Garcia-Chico April 24, 2006
Human error taxonomies
• Errors of omission (not doing the required thing)– Forgetting to do it– Ignoring to do it deliberately
• Errors of commission (doing the wrong thing)– slips in which the operator has the correct motivation or
intention, but carries out the wrong execution• Sequence or wrong order of execution• Timing: too fast/slow
– errors based in erroneous expectations and schema.(schema are sensory-motor knowledge structures stored in
memory used to guide behavior: efficient and low energy)
Jose Luis Garcia-Chico April 24, 2006
Human error taxonomies: SRK model of behavior (Rasmussen, 1982)
Errors depend on behavior: •Skill-based•Ruled-based•Knowledge-based
Jose Luis Garcia-Chico April 24, 2006
Error distinctions
Dimension Skill-based Error Rule-based error Knowledge-based error
Activity Routine Problem solving
Focus of attention Something other than task in hand
Directed to the problem
Control Mode Highly automated (schemata)
Automated (rules: if X then Y)
Conscious process
Detection Rapid and effective
Difficult and often through external intervention
Jose Luis Garcia-Chico April 24, 2006
Generic Error Modeling System-GEMS (Reason, 1990)
Skill-based level
Jose Luis Garcia-Chico April 24, 2006
Human Error Distribution
• Humans are prone to slip & lapses with familiar tasks:– 61% of errors are skill-based
• Humans are prone to mistakes when tasks become difficult.– 28% of errors are rule-based– 11% of errors are knowledge-based that require
novel reasoning from principles.
Approximate data (Reason, 1990) obtained averaging three studies
Jose Luis Garcia-Chico April 24, 2006
Human are error prone, but….is that all?
• It seems that human operator is responsible of system disasters, just because they are the last and more visible responsible of the system performance.
• Distinction between:– Active errors: error associated with the
performance of the front-line operators, i.e. pilots, air traffic controllers, control rooms crews, etc
– Latent errors: related to activities removed in time and space form the direct control interface, i.e. designers, managers, maintenance, supervisors.
Jose Luis Garcia-Chico April 24, 2006
Model of Human Error causation (Reason, 1990)
Accident /mishap
Adapted from Shappel (2000)
Jose Luis Garcia-Chico April 24, 2006
Building solutions
• Each system will require particular instantiation of the approach, but some general recommendations might include:– Prevent errors: procedures, training, safety
awareness, UI design (allow only valid choices)– Tolerate error: UI design (constraints on inputs),
decision support tools– Recover error: undo capability, confirmation
Jose Luis Garcia-Chico April 24, 2006
Learning from past accident/incident
• Great source of lessons to be learnt…not of facts to blame.
• Careful considerations to keep in mind:– Most people involved in accidents are not stupid nor
reckless. They may be only blindness to their actions.
– Be aware of possible influencing situational factors.– Be aware of the hindsight bias of the retrospective
analyst.
Hindsight bias: Possession of output knowledge profoundly influence the way we analyze and judge past events. It might impose a deterministic logic on the observer about the unfolding events that the individual at the incident time would have not had.
Jose Luis Garcia-Chico April 24, 2006
Nine steps to move forward from error:Woods & Cook (2002)
• Pursue second stories beneath the surface to discover multiple contributors.
• Escape the hindsight bias• Understand work as performed at the sharp end of the
system• Search for systemic vulnerabilities• Study how practice creates safety• Search for underlying patterns• Examine how changes create new vulnerabilities• Used new technology to support and enhanced human
expertise• Tame complexity through new forms of feedback
A cased study:
HUMAN FACTOR ANALYSIS OF OPERATIONAL ERRORS IN AIR TRAFFIC CONTROL
Jose Luis Garcia-ChicoSan Jose State University
Master Thesis of Human Factors and Ergonomics
Jose Luis Garcia-Chico April 24, 2006
Motivation of the study
• Some figures - Air Traffic in the USA 2004 (FAA, 2005)– 46,752,000 a/c in en-route operations– 46,873,000 movement in tower operations– 1216 OEs
• OE rate is been increasing during last years (FAA, 2005):– 0.66%* in 2002– 0.78% in 2003– 0.79% in 2004
• Analysis of errors based on initial Air Traffic Controller Reports:– 539 reports (Jan-Jun 2004)
Overview | Method | Research Questions | Initial Results
Jose Luis Garcia-Chico April 24, 2006
Taxonomic study: Initial Results
Overview | Method | Research Questions | Initial Results
OE Classification
0
20
40
60
80
100
120
Fail C
onve
rging
Control
coord
Descen
d trho
ugh
Overlo
oked
Trf
Vector
inad
equ
Hear/Read
back
Altitud
e Ina
dequ
Fail A
lt Clim
b/Des
cend
Rwy Inc
Climb t
hroug
h
Fail O
verta
king-Trf
Instru
c no-i
ntend
ed
temp er
ror-is
sue
Misapp
l Proc
ed
datab
lock-m
isente
r
Airspac
e
Transp
ose a/
c
FPS-mise
nter
Speed
inad
equ
Wron
g a/c
Ocean
Trf
a/c ov
erlap
LOA m
is
Cleared
blw m
in
Misrea
d info
others
/wha
t
ARTCCTRACON
Total OE = 869TRACON = 304ARTCC = 565
Jose Luis Garcia-Chico April 24, 2006
Top-10 OEs
Overview | Method | Research Questions | Initial Results
Top 10-OEs Distribution
Fail Converging14%
Control coord9%
Descend trhough9%
Overlooked Trf9%
Vector inadequ8%
Hear/Readback8%
Altitude Inadequ7%
Fail Alt Climb/Descend
7%
Climb trhough6%
Fail Overtaking-Trf4%
Others19%
Jose Luis Garcia-Chico April 24, 2006
Proximity of encounters: OE output
Proximity Rating - Combined OEs
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0.00 1.00 2.00 3.00 4.00 5.00
Horizontal Distance (NM)
Verti
cal D
ista
nce
(ft)
ABC
Jose Luis Garcia-Chico April 24, 2006
Concurrent and contextual factors
Overview | Method | Research Questions | Initial Results
Top - Contributing Factors
0 20 40 60 80 100 120 140 160
D-side AbsOS Abs/CIC
Combned sect/decombMishearing
MisjudgmentTrf compexity
Training in prgrsNo pilot response/deviation
Distraction Poor Performance Manouever
WX complexityPilot request
Lapse coordinationOther complx
Point Out ComplexityOthers
Not enough info
TRACONARTCC
Jose Luis Garcia-Chico April 24, 2006
Taxonomic study: Initial Results
Overview | Method | Research Questions | Initial Results
DEV vs Prox Rating
0% 10% 20% 30% 40% 50% 60% 70% 80%
Rating A
Rating B
Rating C
None/Unknown
CPCDEV
Jose Luis Garcia-Chico April 24, 2006
Proximity in EOs% Proximity Rating in OEs
0% 20% 40% 60% 80% 100%
Fail ConvergingControl coord
Descend trhoughOverlooked TrfVector inadequ
Hear/ReadbackAltitude Inadequ
Fail Alt Climb/DescendClimb trhough
Fail Overtaking-TrfInstruc no-intended
temp error-issueMisappl Proced
datablock-misenterAirspace
Transpose a/cFPS-misenter
Speed inadequWrong a/ca/c overlap
Misread infoLOA mis
Cleared blw minOthers
ABCNo Rate
Jose Luis Garcia-Chico April 24, 2006
Co-occurrence of OE
Jose Luis Garcia-Chico April 24, 2006
D-side presence/absence
Severtiy of EOs - D-side Present
0 10 20 30 40 50
Fail Overtaking
Overlook TrfFail Converging
Descend Through
Climb Through
Altitude InadeqVector Inadeq
Hear/Readback
Instruc no-intended
Transpose a/cControl Coordination
Data Bolck misenter
Fail Alt Climb Desc
Temp error-issueMisapplication Proc
FPS-Misenter
ABC
Severtiy of EOs - D-side Absent
0 10 20 30 40 50
Fail Overtaking
Overlook Trf
Fail ConvergingDescend Through
Climb Through
Altitude Inadeq
Vector Inadeq
Hear/ReadbackInstruc no-intended
Transpose a/c
Control Coordination
Data Bolck misenter
Fail Alt Climb DescTemp error-issue
Misapplication Proc
FPS-Misenter
ABC
Jose Luis Garcia-Chico April 24, 2006
Time on Position
0
5
10
15
20
25
30
35
40
5 15 25 35 45 55 65 75 85 95 110 >120
Time on Position
#OEs vs Minutes on Position
Jose Luis Garcia-Chico April 24, 2006
Further Reading
• Besnard, D. Greathead, D., & Baxter, G. (2004). When mental models go wrong. Co-occurrences in dynamic, critical systems. International Journal of human Computer Studies, 60, 117-128.
• Dekker, S. W. A. (2002) Reconstructing human contributions to accidents: the new view on error and performance. Journal of Safety Research, 33, pp. 371-385.
• Hollnagel, E. (1993). The phenotype of erroneous actions. International Journal of Man-Machines Studies, 39, 1-32.
• Norman, A. D. (1981). Categorization of slips. Psychological review, 88 (1), 1-15.• Parasuraman, R., Sheridan, T.B., & Wickens, C.D. (2000). A model for types and levels of
human interaction with automation. IEEE transactions on systems, man, and cybernetics-Part A: Systems and humans, 30 (3), 286-297
• Rasmussen, J. (1982). Human errors: A taxonomy for describing human malfunction in industrial installations. Journal of Occupational Accidents, 4, 311-33.
• Rasmussen, J. (1987) The definition of human error and a taxonomy for technical system design. In Rasmussen, J., Duncan, K., & Leplat, J. (Eds.), New Technology and Human Error (pp. 23-30). New York, NY: John Wiley & Sons.
• Reason, J. T. (1990). Human error. Cambridge, England: Cambridge University Press.• Reason, J. T. (1997). Managing the risks of organizational accidents. Aldershot, England:
Ashgate Publishing Company.• Woods, D.D. & Cook, R.I. (2002). Nine steps to move forward from error. Cognition,
Technology, and Work, 4, 137-144.