Robert L Helmreich
On error management: lessons from aviation
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evaluation. The protocol also has potential as a
research instrument since use of a common method
will make analyses of case series of incidents more
powerful. In the meantime, however, it is already prov-
ing a powerful means of investigating and analysing
clinical incidents and drawing out the lessons for
enhancing patient safety.
Copies of the full protocol and details of training programmes
are available from Association of Litigation and Risk
Management (ALARM), Royal Society of Medicine, 1 Wimpole
Street, London W1.
Contributors: CV and ST-A carried out the research on
which the original protocol was based. All authors participated
equally in the development of the protocol, in which successive
versions were tested in clinical practice and refined in the light of
experience. The writing of the original protocol and present
paper was primarily carried out by CV, ST-A, EJC, and DH, but
all authors contributed to the final version. CV and DH are the
Competing interests: CV received funding from Healthcare
Risk Resources International to support the work of ST-A
during the development of the protocol.
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Reason JT. Understanding adverse events: human factors. In: Vincent CA,
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Stanhope N, Vincent CA, Taylor-Adams S, O’Connor A, Beard R. Apply-
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Vincent CA, Adams S, Stanhope N. A framework for the analysis of risk
and safety in medicine. BMJ 1998:316:1154-7.
Taylor-Adams SE, Vincent C, Stanhope N. Applying human factors
methods to the investigation and analysis of clinical adverse events. Safety
Science 1999;31:143-59.
Vincent C, Stanhope N, Taylor-Adams S. Developing a systematic
method of analysing serious incidents in mental health. J Mental Health
Vincent CA, Taylor-Adams S, Chapman EJ, Hewett DJ, Prior S, Strange P,
et al. A protocol for the investigation and analysis of clinical incidents. London:
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ment, 1999.
Reason JT. Human error. New York: Cambridge University Press, 1990.
10 Cooper JB, Newbower RS, Kitz RJ. An analysis of major errors and
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11 Eagle CJ, Davies JM, Reason JT. Accident analysis of large scale
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Anaesth 1992;39:118-22.
12 Cook RI, Woods DD. Operating at the sharp end: the complexity of
human error. In: Bognor MS, ed. Human error in medicine. Hillsdale, NJ:
Lawrence Erlbaum Associates, 1994:255-310.
13 Lord Cullen. The public inquiry into the Piper Alpha disaster. London:
HMSO, 1990.
14 Hughes H. The offshore industry’s response to Lord Cullen’s recommen-
dations. Petroleum Rev 1991 Jan:5-8.
15 Ferrow M. Offshore safety—formal safety assessments. Petroleum Rev 1991
(Accepted 18 February 2000)
On error management: lessons from aviation
Robert L Helmreich
Pilots and doctors operate in complex environments
where teams interact with technology. In both
domains, risk varies from low to high with threats com-
ing from a variety of sources in the environment. Safety
is paramount for both professions, but cost issues can
influence the commitment of resources for safety
efforts. Aircraft accidents are infrequent, highly visible,
and often involve massive loss of life, resulting in
exhaustive investigation into causal factors, public
reports, and remedial action. Research by the National
Aeronautics and Space Administration into aviation
accidents has found that 70% involve human error.1
In contrast, medical adverse events happen to
individual patients and seldom receive national publicity.
More importantly, there is no standardised method of
investigation, documentation, and dissemination. The
US Institute of Medicine estimates that each year
between 44 000 and 98 000 people die as a result of
medical errors. When error is suspected, litigation and
new regulations are threats in both medicine and
Error results from physiological and psychological
limitations of humans.2 Causes of error include fatigue,
workload, and fear as well as cognitive overload, poor
interpersonal communications, imperfect information
processing, and flawed decision making.3 In both avia-
tion and medicine, teamwork is required, and team
error can be defined as action or inaction leading to
deviation from team or organisational intentions.
increasingly uses error management
strategies to improve safety. Error management is
based on understanding the nature and extent of error,
changing the conditions that induce error, determin-
ing behaviours that prevent or mitigate error, and
training personnel in their use.4 Though recognising
that operating theatres are not cockpits, I describe
approaches that may help improve patient safety.
A full explanation
of the threat and
error management
model, with a case
study, appears on
the BMJ’s website
Summary points
In aviation, accidents are usually highly visible, and
as a result aviation has developed standardised
methods of investigating, documenting, and
disseminating errors and their lessons
Although operating theatres are not cockpits,
medicine could learn from aviation
Observation of flights in operation has identified
failures of compliance, communication,
procedures, proficiency, and decision making in
contributing to errors
Surveys in operating theatres have confirmed that
pilots and doctors have common interpersonal
problem areas and similarities in professional
Accepting the inevitability of error and the
importance of reliable data on error and its
management will allow systematic efforts to
reduce the frequency and severity of adverse
Education and debate
Department of
University of Texas
at Austin, Austin,
TX 78712, USA
Robert L
professor of psychology
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Data requirements for error
Multiple sources of data are essential in assessing avia-
tion safety. Confidential surveys of pilots and other
crew members provide insights into perceptions of
organisational commitment to safety, appropriate
teamwork and leadership, and error.3 Examples of sur-
vey results can clarify their importance. Attitudes about
the appropriateness of juniors speaking up when
problems are observed and leaders soliciting and
accepting inputs help define the safety climate.
Attitudes about the flying job and personal capabilities
define pilots’ professional culture. Overwhelmingly,
pilots like their work and are proud of their profession.
However, their professional culture shows a negative
component in denying personal vulnerability. Most of
the 30 000 pilots surveyed report that their decision
making is as good in emergencies as under normal
conditions, that they can leave behind personal
problems, and that they perform effectively when
fatigued.2 Such inaccurate self perceptions can lead to
overconfidence in difficult situations.
A second data source consists of non-punitive inci-
dent reporting systems. These provide insights about
conditions that induce errors and the errors that result.
The United States, Britain, and other countries have
national aviation incident reporting systems that
remove identifying information about organisations
and respondents and allow data to be shared. In the
United States, aviation safety action programmes
permit pilots to report incidents to their own
companies without fear of reprisal, allowing immediate
corrective action.5 Because incident reports are volun-
tary, however, they don’t provide data on base rates of
risk and error.
A third data source has been under development
over 15 years by our project (
helmreich/nasaut.htm). It is an observational method-
ology, the line operations safety audit (LOSA), which
uses expert observers in the cockpit during normal
flights to record threats to safety, errors and their
management, and behaviours identified as critical in
preventing accidents. Confidential data have been col-
lected on more than 3500 domestic and international
airline flights—an approach supported by the Federal
Aviation Administration and the International Civil
Aviation Organisation.6
The results of the line operations safety audit con-
firm that threat and error are ubiquitous in the aviation
environment, with an average of two threats and two
errors observed per flight.7 The box shows the major
sources of threat observed and the five categories of
error empirically identified; fig 1 shows the relative fre-
quency of each category. This error classification is
useful because different interventions are required to
mitigate different types of error.
Proficiency errors suggest the need for technical
training, whereas communications and decision errors
call for team training. Procedural errors may result
from human limitations or from inadequate proce-
dures that need to be changed. Violations can stem
from a culture of non-compliance, perceptions of
invulnerability, or poor procedures. That more than
half of observed errors were violations was unexpected.
This lack of compliance is a source of concern that has
triggered internal reviews of procedures and organisa-
tional cultures. Figure 1 also shows the percentage of
errors that were classified as consequential—that is,
those errors resulting in undesired aircraft states such
as near misses, navigational deviation, or other error.
Although the percentage of proficiency and decision
errors is low, they have a higher probability of being
non-consequential errors
increase risk: teams that violate procedures are 1.4
times more likely to commit other types of errors.8
Managing error in aviation
Given the ubiquity of threat and error, the key to safety
is their effective management. One safety effort is
training known as crew resource management (CRM).4
This represents a major change in training, which had
previously dealt with only the technical aspects of
Sources of threat and types of error observed
during line operations safety audit
Sources of threat
Terrain (mountains, buildings)—58% of flights
Adverse weather—28% of flights
Aircraft malfunctions—15% of flights
Unusual air traffic commands—11% of flights
External errors (air traffic control, maintenance, cabin,
dispatch, and ground crew)—8% of flights
Operational pressures—8% of flights
Types of error—with examples
Violation (conscious failure to adhere to procedures
or regulations)—performing a checklist from memory
Procedural (followed procedures with wrong
execution)—wrong entry into flight management
Communications (missing or wrong information
exchange or misinterpretation)—misunderstood
altitude clearance
Proficiency (error due to lack of knowledge or
skill)—inability to progam automation
Decision (decision that unnecessarily increases risk)—
unnecessary navigation through adverse weather
Type of error
Total errors
Fig 1 Percentage of each type of error and proportion classified as
consequential (resulting in undesired aircraft states)
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flying. It considers human performance limiters (such
as fatigue and stress) and the nature of human error,
and it defines behaviours that are countermeasures to
error, such as leadership, briefings, monitoring and
cross checking, decision making, and review and modi-
fication of plans. Crew resource management is now
required for flight crews worldwide, and data support
its effectiveness in changing attitudes and behaviour
and in enhancing safety.9
Simulation also plays an important role in crew
resource management training. Sophisticated simula-
tors allow full crews to practice dealing with error
inducing situations without jeopardy and to receive
feedback on both their individual and team perform-
ance. Two important conclusions emerge from evalua-
tions of crew resource management training: firstly,
such training needs to be ongoing, because in the
absence of recurrent training and reinforcement,
attitudes and practices decay; and secondly, it needs to
be tailored to conditions and experience within
Understanding how threat and error and their
management interact to determine outcomes is critical
to safety efforts. To this end, a model has been
developed that facilitates analyses both of causes of
mishaps and of the effectiveness of avoidance and miti-
gation strategies. A model should capture the
treatment context, including the types of errors, and
classify the processes of managing threat and error.
Application of the model shows that there is seldom a
single cause, but instead a concatenation of contribut-
ing factors. The greatest value of analyses using the
model is in uncovering latent threats that can induce
By latent threats we mean existing conditions that
may interact with ongoing activities to precipitate
error. For example, analysis of a Canadian crash
caused by a take-off with wing icing uncovered 10
latent factors, including aircraft design, inadequate
oversight by the government, and organisational char-
acteristics including management disregard for
de-icing and inadequate maintenance and training.3
Until this post-accident analysis, these risks and threats
were mostly hidden. Since accidents occur so
infrequently, an examination of threat and error under
routine conditions can yield rich data for improving
safety margins.
Applications to medical error
Discussion of applications to medical error will centre
on the operating theatre, in which I have some experi-
ence as an observer and in which our project has
collected observational data. This is a milieu more
complex than the cockpit, with differing specialties
interacting to treat a patient whose condition and
response may have unknown characteristics.11 Aircraft
tend to be more predictable than patients.
Though there are legal and cultural barriers to the
disclosure of error, aviation’s methodologies can be
used to gain essential data and to develop comparable
interventions. The project team has used both survey
and observational methods with operating theatre
staff. In observing operations, we noted instances of
suboptimal teamwork and communications paralleling
those found in the cockpit. Behaviours seen in a Euro-
pean hospital are shown in the box, with examples of
negative impact on patients. These are behaviours
addressed in crew resource management training.
In addition to these observations, surveys confirm
that pilots and doctors have common interpersonal
problem areas and similarities in professional
culture.2 12 In response to an open ended query about
what is most needed to improve safety and efficiency
in the operating theatre, two thirds of doctors and
nurses in one hospital cited better communications.11
Most doctors deny the deleterious effects of stressors
and proclaim that their decision making is as good in
emergencies as in normal situations. In data just
collected in a US teaching hospital, 30% of doctors
and nurses working in intensive care units denied
committing errors.13
Further exploring the relevance of aviation
experience, we have started to adapt the threat and
error model to the medical environment. A model of
threat and error management fits within a general
Latent threats
National culture, organisational culture, professional culture, scheduling, vague policies
Threat management strategies and countermeasures
Immediate threats
Patient factors
Error detection
and response
patient state
of patient state
Further error
Error management
Fig 2 Threat and error model, University of Texas human factors research project
Behaviours that increase risk to patients in
operating theatres
Failure to inform team of patient’s problem—for
example, surgeon fails to inform anaesthetist of use of
drug before blood pressure is seriously affected
Failure to discuss alternative procedures
Failure to establish leadership for operating room
Interpersonal relations, conflict:
Overt hostility and frustration—for example, patient
deteriorates while surgeon and anaesthetist are in
conflict over whether to terminate surgery after
Preparation, planning, vigilance:
Failure to plan for contingencies in treatment plan
Failure to monitor situation and other team’s
activities—for example, distracted anaesthetist fails to
note drop in blood pressure after monitor’s power fails
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“input-process-outcomes” concept of team perform-
ance, in which input factors include individual, team,
organisational, environmental, and patient character-
istics. Professional and organisational cultures are
critical components of such a model.
Threats are defined as factors that increase the like-
lihood of errors and include environmental conditions
such as lighting; staff related conditions such as fatigue
and norms of communication and authority; and
patient related issues such as difficult airways or
undiagnosed conditions. Latent threats are aspects of
the system predisposing threat or error, such as staff
scheduling policies. The model is shown in fig 2 and is
explained more fully, together with a case study (see
box for summary), on the BMJ ’s website.
At first glance, the case seems to be a simple
instance of gross negligence during surgery by an
anaesthetist who contributed to the death of a healthy
8 year old boy by failing to connect sensors and moni-
tor his condition. When the model was applied,
however, nine sequential errors were identified, includ-
ing those of nurses who failed to speak up when they
observed the anaesthetist nodding in a chair and the
surgeon who continued operating even after the
anaesthetist failed to respond to the boy’s deteriorating
condition. More importantly, latent organisational and
professional threats were revealed, including failure to
act on reports about the anaesthetist’s previous behav-
iour, lack of policy for monitoring patients, pressure to
perform when fatigued, and professional tolerance of
peer misbehaviour.
Establishing error management
Available data, including analyses of adverse events,
suggest that aviation’s strategies for enhancing
teamwork and safety can be applied to medicine. I am
not suggesting the mindless import of existing
programmes; rather, aviation experience should be
used as a template for developing data driven actions
reflecting the unique situation of each organisation.
This can be summarised in a six step approach. As
in the treatment of disease, action should begin with
x History and examination; and
x Diagnosis.
The history must include detailed knowledge of the
organisation, its norms, and its staff. Diagnosis should
include data from confidential incident reporting
systems and surveys, systematic observations of team
performance, and details of adverse events and near
Further steps are:
x Dealing with latent factors that have been detected,
changing the organisational and professional cultures,
providing clear performance standards, and adopting
a non-punitive approach to error (but not to violations
of safety procedures);
x Providing formal training in teamwork, the nature
of error, and in limitations of human performance;
x Providing feedback and reinforcement on both
interpersonal and technical performance; and
x Making error management an ongoing organisa-
tional commitment through recurrent training and
data collection.
Some might conclude that such programmes may
add bureaucratic layers and burden to an already over-
taxed system. But in aviation, one of the strongest pro-
ponents and practitioners of these measures is an
airline that eschews anything bureaucratic, learns from
everyday mistakes, and enjoys an enviable safety
Funding for research into medical error, latent fac-
tors in the system, incident reporting systems, and
development of training is essential for implementa-
tion of such programmes. Research in medicine is his-
torically specific to diseases, but error cuts across all
illnesses and medical specialties.
I believe that if organisational and professional cul-
tures accept the inevitability of error and the
importance of reliable data on error and its
management, systematic efforts to improve safety will
reduce the frequency and severity of adverse events.
Thanks to David Musson, Bryan Sexton, William Taggart, and
John Wilhelm for their counsel.
Funding: Partial support was provided by the Gottlieb
Daimler und Carl Benz Stiftung.
Competing interests: RH has received grants for research in
aviation from the federal government, has been a consultant for
airlines, and has received honorariums for speaking to medical
Helmreich RL, Foushee HC. Why crew resource management? Empirical
and theoretical bases of human factors training in aviation. In: Wiener E,
Case study: synopsis
An 8 year old boy was admitted for elective surgery on
the eardrum. He was anaesthetised and an endotracheal
tube inserted, along with internal stethoscope and
temperature probe. The anaesthetist did not listen to
the chest after inserting the tube. The temperature
probe connector was not compatible with the monitor
(the hospital had changed brands the previous day). The
anaesthetist asked for another but did not connect it; he
also did not connect the stethoscope.
Surgery began at 08 20 and carbon dioxide
concentrations began to rise after about 30 minutes.
The anaesthetist stopped entering CO2 and pulse on
the patient’s chart. Nurses observed the anaesthetist
nodding in his chair, head bobbing; they did not speak
to him because they “were afraid of a confrontation.”
At 10 15 the surgeon heard a gurgling sound and
realised that the airway tube was disconnected. The
problem was called out to the anaesthetist, who
reconnected the tube. The anaesthetist did not check
breathing sounds with the stethoscope.
At 10 30 the patient was breathing so rapidly the
surgeon could not operate; he notified the anaesthetist
that the rate was 60/min. The anaesthetist did nothing
after being alerted.
At 10 45 the monitor showed irregular heartbeats.
Just before 11 00 the anaesthetist noted extreme
heartbeat irregularity and asked the surgeon to stop
operating. The patient was given a dose of lignocaine,
but his condition worsened.
At 11 02 the patient’s heart stopped beating. The
anaesthetist called for code, summoning the
emergency team. The endotracheal tube was removed
and found to be 50% obstructed by a mucous plug. A
new tube was inserted and the patient was ventilated.
The emergency team anaesthetist noticed that the
airway heater had caused the breathing circuit’s
plastic tubing to melt and turned the heater off. The
patient’s temperature was 108°F. The patient died
despite the efforts of the code team.
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Kanki B, Helmreich R, eds. Cockpit resource management. San Diego: Aca-
demic Press, 1993:3-45.
Amalberti R. La conduite de systèmes à risques. Paris: Presses Universitaires
de France, 1996.
Helmreich RL, Merritt AC. Culture at work: national, organisational and
professional influences. Aldershot: Ashgate, 1998.
Helmreich RL, Merritt AC, Wilhelm JA. The evolution of crew resource
management in commercial aviation. Int J Aviation Psychol 1999;9:19-32.
Federal Aviation Administration. Aviation safety action programs. Washing-
ton, DC: FAA,1999. (Advisory circular 120-66A.)
Helmreich RL, Klinect JR, Wilhelm JA. Models of threat, error, and CRM
in flight operations. In: Proceedings of the tenth international symposium on
aviation psychology. Columbus: Ohio State University, 1999:677-82.
Klinect JR, Wilhelm JA, Helmreich RL. Threat and error management: data
from line operations safety audits. In: Proceedings of the tenth international
symposium on aviation psychology. Columbus: Ohio State University,
Helmreich RL. Culture and error. In: Safety in aviation: the management
commitment: proceedings of a conference. London: Royal Aeronautical
Society (in press).
Helmreich, RL, Wilhelm JA. Outcomes of crew resource management
training. Int J Aviation Psychol 1991:1:287-300.
10 Reason J. Managing the risks of organisational accidents. Aldershot:
11 Helmreich RL, Schaefer H-G. Team performance in the operating room. In:
Bogner MS, ed. Human error in medicine. Hillside, NJ: Erlbaum, 1994:
12 Helmreich RL, Davies JM. Human factors in the operating room: Interpersonal
determinants of safety, efficiency and morale. In: Aitkenhead AA, ed. Baillière’s
clinical anaesthesiology: safety and risk management in anaesthesia.
London: Ballière Tindall, 1996:277-96.
13 Sexton JB, Thomas EJ, Helmreich RL. Error, stress, and teamwork
in medicine and aviation: cross sectional surveys. BMJ 2000;320:
Anaesthesiology as a model for patient safety in health care
David M Gaba
Although anaesthesiologists make up only about 5% of
physicians in the United States, anaesthesiology is
acknowledged as the leading medical specialty in
addressing issues of patient safety.1 Why is this so?
Firstly, as anaesthesia care became more complex
and technological and expanded to include intensive
care it attracted a higher calibre of staff. Clinicians
working in anaesthesiology tend to be risk averse and
interested in patient safety because anaesthesia can be
dangerous but has no therapeutic benefit of its own.
Anaesthesiology also attracted individuals with back-
grounds in engineering to work either as clinicians or
biomedical engineers involved in operating room
activities. They and others found models for safety in
anaesthesia in other hazardous technological pursuits,
including aviation.2 3
Secondly, in the 1970s and ’80s the cost of
malpractice insurance for anaesthesiologists in the
United States soared and was at risk of becoming un-
available. The malpractice crisis galvanised the profes-
sion at all levels, including grass roots clinicians, to
address seriously issues of patient safety. Thirdly, and
perhaps most crucially, strong leaders emerged who
were willing to admit that patient safety was imperfect
and that, like any other medical problem, patient safety
could be studied and interventions planned to achieve
better outcomes.
Accomplishments in patient safety in
Anaesthesia: safer than ever
It is widely believed that anaesthesia is much safer
today (at least for healthy patients) than it was 25 or 50
years ago, although the extent of and reasons for the
improvement are still open to debate. Traditional
epidemiological studies of the incidence of adverse
events related to anaesthesia have been conducted
periodically from the 1950s onwards.4–6 Many of these
studies were limited in scope, had methodological con-
straints, and cannot be compared with each other
because of differing techniques. An important out-
come has been the emergence of non-traditional
investigative techniques that aim not to find the true
incidence of adverse events but to highlight underlying
characteristics of mishaps and to suggest improve-
ments in patient care.
Such techniques have included the “critical incident”
technique adapted by Cooper from aviation2 7; the
analysis of closed malpractice claims8; and the Australian
incident monitoring study (AIMS).9–12 These approaches
analyse only a small proportion of the events that occur
but attempt to glean the maximum amount of useful
information from the data.
Technological solutions
Once the range of patient safety problems in anaesthe-
siology had been defined, several strategies have been
used to improve safety. One is to apply technological
solutions to clinical problems. Anaesthesiologists have
become expert at realtime monitoring of patients
(both electronically and via physical examination). In
the industrialised world electrocardiography, pulse
oximetry, and capnography (analysis of carbon dioxide
in exhaled gas) have become standards and are
thought to have contributed substantially to safety. No
study to date, however, has had sufficient power to
prove an outcome benefit from the use of these
Summary points
Anaesthesiology is acknowledged as the leading
medical specialty in addressing patient safety
Anaesthesia is safer than ever owing to many
different types of solutions to safety problems
Solution strategies have included incorporating
new technologies, standards, and guidelines, and
addressing problems relating to human factors
and systems issues
The multidisciplinary Anesthesia Safety
Foundation was a key vehicle for promoting
patient safety
A crucial step was institutionalising patient safety
as a topic of professional concern
Although anaesthesiology has made important
strides in improving patient safety, there is still a
long way to go
Education and debate
Patient Safety
Center of Inquiry,
112PSCI, VA Palo
Alto Health Care
System, 3801
Miranda Avenue,
Palo Alto, CA
94304, USA
David M Gaba
[email protected]
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