Investigating "Causes" and Assigning
Ira J. Rimson, P.E.;
2120 Kirby St. NE;
Albuquerque, NM 87112-3476
Determining "Causes" of mishaps has long been a source of
ignition for arguments in the safety community. Few safety practitioners
comprehend how seriously investigations have been contaminated by the
uncritically accepted goals of "Probable Cause" and "Blame," and how severely
they have hindered prevention initiatives.
who originally established causal determination as an investigative goal
neglected to establish definitions against which investigators' results could
be measured. As a result, weak investigative rigor has been accepted
uncritically. Simple early systems accommodated rudimentary investigations;
current technological complexity does not. We can no longer afford to indulge
in unscientific, unvalidated, non-standard investigation methodologies which
produce unverifiable conclusions. Vague recommendations arising from these unsubstantiable
data lack any reliable means for determining their usefulness for correcting
techniques employ historic and assumed data to identify and rank risks,
attempting to predict vulnerability of new systems. Yet after those new systems
start operating, anomalies, deviations, disruptions, failures,
accidents and catastrophes occur. These real world mishaps afford opportunities
to identify limitations and faulty assumptions of early predictions. The safety
community must evaluate the validity of both predictive and deterministic
(after the fact) methodologies. Concentration on assigning causes and blame has
failed to halt preventable mishaps by creating illusions of understanding.
paper will propose alternative methodologies which analyze the Logic of
Causation, and propose reviving a 160-year-old definition of "Cause" --that of
precursor (as in cause-and-effect). The increased rigor which results will
generate more robust evaluation data. Better data will validate both predictive
and deterministic models. Valid models will be benchmarks against which
standardized, logic-based investigations may be verified. Verified
investigation outcomes will identify potentially successful intervention
strategies which deter occurrence.
obstacle to discovering the shape of the earth, the continents
and the oceans
was not ignorance, but the illusion of knowledge."
Librarian Emeritus of the U.S.
is a "Cause"
If "probable cause" is OK for safety (and I doubt it),
it certainly is unsatis-factory for prevention, and entirely unacceptable for
investigations. Who wants to pay for an investigation whose result is "probable
cause" except someone who doesn't want to know for sure anyhow?
Fire/Explosion Investigator, Canada
the outset let's take a brief look at a well-known modern vision of cause: the
concept of causation as expressed in the phrase "Probable Cause" by the National
Transportation Safety Board (NTSB). "Cause", as applied to the objectives of
government air safety investigations, evolved without definition along an
"Cause" first appeared as a duty of the
Department of Commerce in þ172 of the Air Commerce Act of 1926:
Department] shall... (e) investigate, record and make public the causes of accidents....
Cause" materialized in the 1934
Amendment to the Air Commerce Act of 1926, which merged the
formerly scattered aviation functions of the Department of Commerce's Aviation
Branch into the Bureau of Air Commerce:
. . .
the Secretary of Commerce shall, if he deems it in the public interest, make
public a statement of the probable cause or causes of the accident....
Civil Aeronautics Act of 1938 established a Safety Board within the
Civil Aeronautics Authority, assigning to it in þ702 duties to:
investigate such accidents and report to the Authority the facts, conditions,
and circumstances relating to each accident and the probable cause thereof; and
make such recommendations to the Authority as, in its opinion, will tend to
prevent similar accidents in the future;
Federal Aviation Act of 1958 established both the Federal Aviation
Administration and the Civil Aeronautics Board, assigning to the CAB
responsibility for "...the promotion of safety in air commerce." A duty
of the CAB specified in þ701 was to:
investigate such accidents and report the facts, conditions, and circumstances
relating to each accident and the probable cause thereof;
Department of Transportation Act of 1966 established the
Department of Transportation, interposing it as a managerial layer superior to
the FAA; and the National Transportation Safety Board. In þ5 it established the
duties of the NTSB, including:
determining the cause or probable cause of transportation accidents”;
Independent Safety Board Act of 1974 established the NTSB as an
independent agency of the U.S. federal government, and established among its
duties in þ304:
investigate or cause to be investigated (in such detail as it shall prescribe),
and determine the facts, conditions, and circumstances and the cause or
probable cause or causes of
The roles of
successive investigative agencies evolved from determining "cause" to "probable
cause" to "cause or probable cause" to "cause or probable cause or causes", yet
agency managers and investigators were denied any comprehensive statutory
definitions of "cause" or "probable cause." It was as though the bureaucrats
who drafted the legislation didn't really "...want to know for sure anyhow."
description of the CAA Air Safety Board 's interpretation of "probable cause"
by Jerome F. "Jerry" Lederer, then its Director, has survived:
therefore, endeavor to state how the accident happened and why. The "why" is
our conclusion expressed in terms of probable cause and contributing
factors.... It has been our endeavor to stick to a practical pattern which
the proximate cause as the probable cause and sets up the underlying or more
remote causes as contributing factors. (Le:42)
both "proximate cause" and "probable cause" are legal terms of art; i.e., they possess specific meanings within the context
in which they are applied. The two terms are defined as follows in their legal
That which, in a natural and continuous sequence, unbroken by any efficient
intervening cause, produces injury, and without which the result would not have
That which is next in causation to the effect, not necessarily in time or
space but in causal relation.
The proximate cause of an injury is the primary or moving cause, or that
which, in a natural and continuous sequence, unbroken by any efficient
intervening cause, produces the injury and without which the accident could not
have happened, if the injury be one which might be reasonably anticipated or
foreseen as a natural consequence of the wrongful act.
An injury or damage is proximately caused by an act or a failure to act,
whenever it appears from the evidence in the case, that the act or omission
played a substantial part in bringing about or actually causing injury or
damage; and that the injury or damage was either a direct result or a
reasonably probable consequence of the act or omission.
for "Probable Cause":
Reasonable cause; having more evidence for than against.
A reasonable ground for belief in certain alleged facts.
A set of probabilities grounded in the factual and practical considerations
which govern the decisions of reasonable and prudent persons and is more than
mere suspicion but less than the quantum of evidence required for conviction.
An apparent state of facts found to exist upon reasonable inquiry (that is,
such inquiry as the given case renders convenient and proper), which would induce a reasonably intelligent
and prudent man to believe, in a criminal case, that the accused had committed
the crime charged, or, in a civil case, that a cause of action existed.
The evidentiary criterion necessary to sustain an arrest or the issuance of
an arrest or search warrant.
apply the legal definitions of "proximate cause" and "probable cause" to an
investigation context results in instant incomprehensibility. Worse yet, these
legal definitions add the following vague abstractions to the original
anticipation foreseeability natural
& prudent mere
state of facts
than the quantum of evidence needed to convict
as well as still
more undefined concepts of cause:
Rules of law
often retain some vagueness to permit flexibility in applying them to
unforeseen circumstances. (CoCo:90) Equivocation has utility for an attorney
attempting to prove or refute the elements of legal proof required to convince
a jury of a client's guilt or innocence. However, that kind of definitional
elasticity is not conducive to the foundation of investigation: scientific
hypothesis testing. By establishing undefined "causes" or "probable causes" as
their principal investigation objective, investigation authorities created a
quandary for investigators who try to apply objective methodologies to the
study and understanding of how mishaps occur. In the absence of any more
precise definitions against which to measure their conclusions, it is
impossible for investigators to determine the causes or probable causes of
Other Concepts of Causation
It is usually between a consequent and the sum of several
antecedents; the concurrence of them all being requisite to produce, that is,
to be certain of being followed by the consequent. In such cases it is very
common to single out only one of the antecedents under the denomination of
Cause, calling the others merely conditions.... The real Cause is the whole of
these antecedents; and we have, philosophically speaking, no right to give the
name of causes to one of them exclusively of the others.
John Stuart Mill (Mi:43)
formal methodologies have been designed specifically to investigate
deterministic events (which have already happened), compared to the myriad
which have been developed to support probabilistic risk assessments (which
attempt to predict what might happen in
the future). Two prominent methodologies have been used for deterministic
analyses of industrial, chemical and nuclear mishaps:
Oversight and Risk Tree (MORT) Analysis.
"Method: Apply a pre-designed, systematized logic tree to
the identification of total system risks, both those inherent in physical
equipment and processes, and those which arise from operational/management
"Application: The pre-designed tree, intended as a comparison
tool, generally describes all phases of a safety program and is applicable to
systems and processes of all kinds. The technique is of particular value in
accident/incident investigation as a means of discovering system or program
weaknesses or errors which provide an environment conducive to mishaps.
"Product: Comparison between the actual system and the model
"tree", which results in assignments of general weaknesses or errors as
"Less-Than-Adequate" factors to which causation may be attributed."
"Method: The process [uses] a
structured MORT-based system with adjustments made to suit a particular usage.
The MORT method defines 23 categories of surface causes or investiga-tion
findings that help provide the foundation for the subsequent development of
root causes. By arranging "why" statements into surface and root cause
categories, [investigators] can focus on why the investigation's findings
occurred rather than the specifics of the findings themselves. Analyzing this
information consists of observing the frequency and weight placed on items,
not-ing common threads that seem to flow through the statements, and making
professional interpre-tations and intuitive judgments to deduce underlying root
causes for each investigation finding.
"Application: ...to determine the underlying contributing reasons
(root causes) for the observed deficiencies documented in the findings of an
investigation. By emphasizing a few root causes, management can correct a wide
variety of deficiencies or faults in a system.
"Product: Identified dependent causes are grouped to common
causes, which are then reduced where possible to single root causes applicable
to a set of related deficiencies, shortcomings or observations."
In merely two
methodologies we have uncovered the following new, and as yet still undefined,
descriptions of causation:
risks inadequacies weaknesses errors
factors surface causes findings root
causes shortcomings observations
Uncertainty, Ambiguity and Vagueness
and correct use of language is a powerful aid to straight thinking, for putting
into words precisely what we mean necessitates getting our own minds quite
clear on what we mean. - William,
three linguistic concepts are probably known abstractly to investigators, but
they apply quite specifically to investigations and their objectives:
Uncertainty = "not definitely ascertainable or fixed, as in time of occurrence,
number, dimensions, quality, or the like"; in scientific terms, the object
cannot be "classified".
Ambiguity = "having several possible meanings or interpretations, equivocal";
in scientific terms, the object cannot be "discriminated".
Vagueness = "indefinite or indistinct in nature or character, as ideas,
feelings, etc."; thus incapable of being either classified or
concepts are significant to investigators, who must eliminate as much
uncertainty, ambigu-ity and vagueness as possible during the investigation
process. Both uncertainty and ambiguity can eventually be resolved by
sufficient data, information and facts. Vagueness, on the other hand, cannot. A
vague term is itself inherently incapable of classification; its very
definition lacks sufficient precision to enable either classification or
the terms "cause" or "probable cause" from their legal definitions to
scientific appli-cations led to increasing vagueness and indeterminacy. No
amount of additional information or data can help us identify the terms "cause"
or "probable cause". Their lack of definition doesn't define what we're looking
for. Likewise, substitution of euphemisms or terms of art detracts from precise
meaning. As a result, we cannot determine what it is we're looking for, where
to find it, how to get to where it might be, how to recognize it (if by chance
we do stumble upon it), or how to verify its identity.
A can always exceed B if not all of B is counted and/or if A is exaggerated.
- Thomas Sowell
the past generation our society has become fixated on assigning blame. This
phenomenon may have arisen from a false expectation of perfection which
originated from quantum leaps of technological advancement. It may be an
outgrowth of our society's unwillingness to require individuals to be
accountable for the results of their actions. (It is just as likely a byproduct
of a plethora of hungry lawyers.) In any case, we no longer accept with
passivity the motto of the '60s, "S*** Happens!". Instead, we assume that
someone must blameworthy, so we find a hungry lawyer and sue.
corollary of ill-defined concepts of causation has been the ease with which
causes can be assigned. Assigning causes requires little more than pointing
fingers and assessing blame. Gerard Bruggink, then Deputy Director of the
NTSB's Bureau of Air Safety, rebutted those who argued that investigators do
not indulge in casting blame:
emphasizing 'Who Caused the Accident?' rather than 'What Might Have Prevented
It?', investigation authorities engage in weighing causes and, therefore,
weighing blame. Causal summaries identify the individuals and organizations
that seem to be most at fault, balancing between probable cause and
his muddying the semantic waters with references to "fault" and the
still-undefined "probable cause" and "contributing factors", Bruggink raised a
valid point. Investigators may assign blame for any number of reasons. In my
experience the most prevalent is that it is easier than spending the time and
effort to identify specifically what went wrong and why. They conclude that the
event itself is evidence that some person or persons did something that caused,
or failed to do what was necessary to avoid the occurrence. It is consistent
with the bottom line of MORT analyses, that something or other was "Less Than
Adequate." Our friends at the UK's Aircraft Accident Investigation Board call
it the "BGO" - Blinding Glimpse of the Obvious! Lawyers have a Latin term which
encompasses the mind-set: Res Ipsa Loquitur
- "the thing speaks for itself." Once the thing has spoken, as a result of a
mishap, the simplest response is to lay the blame on the most convenient
are various reasons why investigators should not assign blame, not the least of
which is the likelihood of tainting their investigation by selective acceptance
of facts which support their charges. Blame requires subjective evaluation of
alleged acts committed or omitted by persons involved in a mishap. Mishap
reports often contain obvious clues to investigator subjectivity:
Ö Judgmental verbs; e.g., "failed to" or "did not", without
specifying precisely the alleged error(s) of omission, and the law, regulation
or procedure with which the actor allegedly failed to comply, and how that
contributed to the outcome.
Ö Comparative adjectives; e.g., "improperly" or "incorrectly", likewise
absent support-ing data specifying how the act varied from expectation, and how
that influenced the outcome.
indulge in such judgments occurs because:
Ö The investigator "knows" from personal
experience what the actor "should have" done, and assumes that it wasn't done
properly because the mishap occurred; or
Ö The investigator doesn't know what the
actor should have done, and assumes that obviously something wasn't done
properly because the mishap occurred. (Be:95)
The Investigators' Role
The greatest tragedy of science is that you often slay
a beautiful hypothesis with an ugly fact. - Thomas Huxley
investigators' role, quite simply, is to determine What Happened, with scientific rigor and proof.
Investigators must identify facts, conditions and circumstances as their first
order of business. This is not a simple task. Benner
has suggested that an accident "...can be viewed as an unscheduled and largely
uninstrumented scientific experiment performed to test a hypothesis (or
theory)." (Be:75) The investigator is privy to the results, and is faced with
the task of deter-mining where, when and how it began, and what route it took
to get to the ending. Investigation has frequently been characterized as "more
art than science," an oversimplification which has not benefited from such
popular video dramas as "CSI." Only within the past few decades have investigative
methodologies emerged which combine robust, scientifically based hypothesis
testing with the discipline of formal logical analysis.
technological advances have led to more complex and interactive systems, it has
become obvious that one, or a few, "probable causes" cannot account for the
evolutionary processes that lead to accidental outcomes. Accidents themselves
are complex processes, often generating over extended time periods.
Prerequisite conditions for undesired outcomes may have been estab-lished
years, or even decades, before.
amongst investigative philosophies can been seen by contrasting the
investigations into the mishaps which befell NASA's Challenger and Columbia. Challenger was the
subject of three separate investigations, each of which was
tainted by the pre-ordaining mind-set of its investigators. Yet it was an
independent examination of the organizational behavior of persons within the
involved agencies that first considered corporate cultures which were
prerequisite to the decisions that enabled the explosion. (Va:96) Although the
final report of the Columbia
Accident Investigation Board is not complete as of this writing, the Board's
independence from pressures by interested parties has enabled it to address
issues that were ignored, if recognized at all, during the initial Challenger investigations. Although NASA's management
apparently learned little from Challenger's loss, Columbia's Investigation Board certainly learned a great deal
from Challenger's investigations.
the first priority of the investigation is identifying the "facts, conditions
and circumstan-ces" relating to the mishap under investigation, the issue of
causal vagueness is eliminated. Facts, conditions and circumstances may be
uncertain or ambiguous, but those problems can be overcome by additional facts,
data and information. Facts, conditions and circumstances are never vague. They
are tangible, measurable descriptions of what happened. Once we know what
happened, we can recast the scenario into
specific events and conditions which permit applying the tests and proofs of
The Logic of
hundred years ago Sir Francis Bacon recognized that simple enumeration of
events was inadequate methodology with which to conduct inductive logical
analyses. John Stuart Mill (1806-1873) developed his classical canons of
inductive inference which encompass concepts of causation and effect. (CoCo:90)
These methodologies are essential tools which enable investiga-tors to develop what
happened - establishing with rigor the
structure of causation which was precursor to the effect. Mill's enduring
principles have been adapted to the task of accident investigation and analysis
in at least two specific applications.
Benner, Jr., has developed "Multilinear Events
Sequencing" ("MES") over more than two decades. It posits that a mishap is a
total process, of which only the end event is initially accessible to the
investigator. MES affords the investigator an ordering discipline within which
a matrix of predecessor events are arrayed to reconstruct the process which led
to the undesired outcome, over the time period of the mishap. Once the matrix
is generated the investigator or analyst compares discrete patterns of
"event-pairs" which occurred during the mishap process, and applies sequential,
causeÞeffect, and necessity and
sufficiency logic tests. (HeBe:86) and (Be:97) Benner's most
recent application uses the reported facts of an industrial accident
investigation to compare analyses by competing investigation methodologies.
Ladkin et al
have developed "WB-analysis" (from "Why-Because"). It is a suite of methods for explaining complex
system failures based on formal semantics and logic. WB-analysis is primarily concerned with analyzing reported
causality a posteriori. The list
of events, states and processes (short coherent sequences of actions and states
that do not need to be analyzed into components) stated in accident reports are
taken to be inputs to the causal analysis. WB-a enables the investigator or analyst to identify
significant system states and events, express them as propositional variables,
build a chronological graph of causal-factor relationships among sequential
sets of variables, and apply counterfactual testing. Semantic testing is
applied to these pairwise, to obtain the a WB-graph, first in textual form and then in graphical form.
(GeHo:97) and (GeLa:97a)
The differences between MES and WB-a lie principally in their evolution: MES is designed
to assist the investigator by formalizing the investigation process; WB-a is a tool for conducting formal analyses of
investigation conclusions. Despite their differences, both MES and WB-a have utility for investigators and investigation
The Need for Testing
every expert there is an equal and opposite expert, but for every fact there is
not necessarily an equal and opposite fact. - Thomas Sowell
can reduce their vulnerability to criticism from special interests by
aggressively applying CauseÞEffect
logic, testing their hypotheses and demonstrating replicability of their
conclusions. Testing need not be complicated. Simple counterfactual tests which
demonstrate logical reasoning are far more convincing than subjective,
intuitive "causes" which require blind acceptance of the investigators' ipse
CauseÞEffect logic self-tests by
hypothesizing counterfactual arguments; i.e.,
If Cause A results in Effect B, then
of Cause A will result in absence of Effect B.
Remove Cause A.
Effect B still happens, then Cause A cannot "cause"
his theory of Constraints, Goldratt
proposed that each cause normally has more than one effect. To test the
validity of the investigator's assumed CauseÞEffect logic, the analyst must find evidence of yet
another expected coincident effect. (Go:90) Goldratt calls this phenomenon the
"Effect-Cause-Effect" test. Dettmer restates it as follows (De:97):
we accept that [CAUSE] is the reason for [ORIGINAL EFFECT], then it must also
lead to [PREDICTED EFFECT(S)], which [do/do not] exist.
eight Categories of Legitimate Reservation which should be tested to assure
that analytical logic has been verified:
Predicted-Effect Existence, and
manner of hypothesis testing investigators choose to employ, its objectivity
will discourage the kind of controversies that arise, and survive to do
mischief long after the mishap may be forgotten. By removing "judgment calls"
from the investigation and analysis process, robust logical assessments force
critics to demonstrate that their
theories conform more logically with the factually-derived chronology of what
Prevention: A Measure of Investigation Accuracy
Anyone can make a decision, given enough facts.
A good manager can make a decision without enough facts.
A perfect manager can operate in perfect ignorance.
- Spencer's Laws of Data
early as 1938 the Safety Board within the Civil Aeronautics Authority was
and report the facts, conditions, and circumstances relating to each accident,
and make recommendations that would tend to prevent similar accidents in the
future It seems evident that the "facts,
conditions and circumstances" were intended to be prerequisite to, and form the
bases for, recommendations for correcting the process defects which enabled the
mis-hap, and thereby preventing recurrence. Nevertheless many (if not most)
organizations which control investigations choose to elevate the task of
determining "cause(s)" to preeminence, a choice that has never seriously been
questioned. These agencies have maintained the priority of causal determination
even as it has become obvious that many assigned "cause(s)" cannot be
substantiated by the facts, conditions and circumstances in their specific
cases. "Cause" is, by definition, vague; "probable cause," "root cause," and
other adjective-causes are even more vague. "Accidents" are the concluding
events of specific, and usually unique, mishap processes.
or several, "cause(s)" cannot account for complex, evolutionary mishap
processes. Prede-termined menus are futile attempt to generate standard
categories from which analysts can assign causation by picking "one from column
A" or "two from column B," confident of the conventional wisdom that one size
cause fits all facts.
corrective and preventive action is corollary to vaguely specified causation.
Recom-mendations for mitigation or prevention have been largely ineffective in
forestalling the seeming inevitability of common accident mechanisms.
Effecting corrections and preventing recurrence require specific identification
of what went wrong, and precise remedies to change the behaviors which either
enabled the progress of the mishap process, or failed to recognize and arrest
it. They demand action to identify specific dysfunctionalities, trace their
origins and change the behavior which led both to and from them. Not only do
rational investigations prevent similar mishaps, they also identify and
mitigate against perpetuation of process inefficiencies and wasted investment.
two objectives - determining causation, and improving system performance -- are countervalent; that is, they are so
fundamentally inconsistent that increasing concentration on one diminishes the
worth of the other. So long as we cannot even define what "causes" are, efforts
expended in their quest are squandered. Worse yet, the more vague the subsumed
causal elements, the more efforts must be devoted to searching for things which
have not, and cannot, be defined.
suboptimal system performance requires identification of specific human
behaviors which facilitated departure from the original planned mission
scenario and objectives, into an unplanned path to an undesired outcome. Make
no mistake, human behavior sets the stage. Inanimate objects are incapable of
making volitional decisions. In the words of the eminent aviator,
mishap investigator and psychologist Captain Robert O. Besco, Ph.D:
humans are caused by accident, but all accidents are caused by humans.
must identify the specific human behaviors which led to disrupting the original
plan. Facts, conditions and circumstances are never vague. They are tangible,
measurable descriptions of what happened. Once we know what happened, we can
dissect the scenario into events and conditions which encourage application of
formal logic's tests and proofs. Legitimate causeÞeffect
relationships which determine the progress of a mishap process can identify
potential early intervention points which possess realistic probabilities for
effecting prevention and process improvement.
the most part we have no idea whatsoever whether investigations and their
recommenda-tions support our professed objectives for their accomplishment. We
do not measure objectively whether recommended "fixes" actually work. It is
possible - even probable - that a substantial proportion of current "safety"
regulations, policies, and operational procedures have no effect on achieving
system improvement or, worse yet, are actually inimical to our objectives.
Investigators' work products should be the principal sources for identifying
factors upon which to base systems' improvements. The usefulness of those work
products depends on investigations' incorporating rigorous methodologies which
establish, test and verify their conclusions and recommendations. It is not
enough for investigation sponsors merely to generate arbitrary recommendations.
Those which arise from fallacious "causes" cannot contribute to improvement.
Even those derived from the findings of competent investigations should be
tracked after implementation to verify their efficacy.
Where Do We Go From Here?
that will not apply new remedies must expect new evils, for time is the
greatest innovator. -
Sir Francis Bacon
in his book Managing Risk, Dr. Vernon
Grose makes the point that:
managers, acting as though an accident is a random stroke of fate, have to be
reminded to seek and remove causes prior to a loss. (emphasis in the original)
investigator's success depends a great deal upon the culture within the
organization by which he is empowered. It is appropriate for the investigator
to establish the fundaments of his duties early on. For example, what objective
has the greater opportunity for benefiting the company, its industry and its
customers: determining "cause(s)," or improving the operation?
the aftermath of the ValuJet crash in Florida in 1996, William Langewiesche
compiled a roster of lessons which we need to learn, not least those
responsible for investigating accidents and attempting to prevent their
recurrence.(La:98) Although directed at the aviation industry and its
government regulatory agency, it is applicable to all investigators and
can find fault among those directly involved - and we probably need to. But if
our purpose is to attack the roots of such an accident, we may find them so
entwined with the system that they are impossible to extract without toppling
the whole structure....Beyond the question of blame, it requires us to consider
that our solutions, by adding to the complexity and obscurity of the airline
business, may actually increase the risks of accidents. ...
ValuJet case...fits the most basic definitions of an accident caused by the
very functioning of the system or industry within which it occurred.... The two
unfortu-nate mechanics who signed off on the nonexistent safety caps just
happened to be the slowest to slip away when the supervisors needed signatures.
Other mechanics almost certainly would have signed too, as did the
inspectors.... The falsification they committed was part of a larger deception
- the creation of an entire pretend reality that includes unworkable chains of
command, unlearnable training pro-grams, unreadable manuals, and the fiction of
regulations, checks and controls. Such pretend realities extend even into the
most self-consciously progressive large organizations, with their attempts to
formalize informality, to deregulate the workplace, to share profits and
responsibilities, to respect the integrity and initiative of the individual.
The systems work in principle, and usually in practice as well, but the two may
have little to do with each other. Paperwork floats free of the ground and
obscures the murky workplaces where, in the confusion of real life, system
accidents are born.
and the organizations on whose behalf they investigate must recognize and
expose systemic unsuitabilities, unfitness and irrelevance, and recommend
changes even to those regulatory and administrative dogmas that have survived
unquestioned since they were first written. Gerard Bruggink once averred that
the principal factor in accident causation is the "...uncritical acceptance of
easily verifiable assumptions." We would establish much more credibility and
achieve much greater success were we to replace "uncritical acceptance" with
more stringent verification.
Benner, Jr., "Accident theory and Accident Investigation." Proceedings of
the Society of Air Safety Investigators Annual Seminar, Ottawa, Canada,
October 7-9, 1975, pp. 148-154. At: http://www.iprr.org/papers/75iasiatheory.html
Benner, Jr., "Words Mean Something." ISASI forum, V. 28, #3, (September 1995). Sterling, VA.,
International Society of Air Safety Investigators. At: http://www.bjr05.net/papers/Words.htm
Ludwig Benner, Jr., Introduction
to Investigation. (Stillwater, Oklahoma
State University Fire Protection Publications, 1997). Available from
Emergency Film Group, Edgartown, MA
Ludwig Benner, Jr.,
"Investigating Investigation Methodologies." Presented at the \2nd Workshop
on the Investigation and Reporting of Incidents and Accidents (IRIA03), 16 -
19 September 2003, Williamsburg, VA
Bruggink, "To Kill a Myth." Proceedings of the Eighteenth International
Seminar of the International Society of Air Safety Investigators, Atlanta,
Georgia, October 6-9, 1988. ISASI forum, V. 20, #4, February 1988, pp. 4-9.
Copi & Carl Cohen, Introduction to Logic, 8th ed. (New York, Macmillan, 1990) [ISBN 0-02-325035-6]
Dettmer, Goldratt's theory of Constraints. (Milwaukee, American Society for Quality Press, 1997) [ISBN
Gerdsmeier, Michael Hñhl, Peter Ladkin & Karsten Loer, "How Aircraft
Crash," 11 June 1997. RVS Group, Technical Faculty, University of Bielefeld.
Gerdsmeier, Peter Ladkin & Karsten Loer, "Formalising Failure Analysis."
RVS Group, Technical Faculty, University of Bielefeld. at http://www.rvs.uni-bielefeld.de/~ladkin/Reports/AMAS97.html
Gerdsmeier, Peter Ladkin & Karsten Loer, "Analysing the Cali Accident
With a W-B Graph." Presented at the Human Error and Systems Development
Workshop, Glasgow, March 1997. (Second Version, 13 March 1997). at http://www.rvs.uni-bielefeld.de/~ladkin/Reports/caliWB.html
Goldratt, theory of Constraints.
(Great Barrington, North River Press, 1990) [ISBN 0-88427-085-8]
Grose, Managing Risk: Systematic Loss Prevention for Executives. (Englewood Cliffs, Prentice-Hall, 1987) [ISBN
Hendrick & Ludwig Benner, Jr., Investigating Accidents with STEP. (New York, Marcel Dekker, 1986) [ISBN
Langewiesche, "The Lessons of ValuJet 592." The Atlantic Monthly, March 1998, pp. 81-98.
Lederer, (Director, Safety Bureau), Memorandum to the Civil Aeronautics
Board dated June 12, 1942. Subj: "Basic
system of analyzing aircraft accidents", pp. 2-3.
Lederer, "Is Probable Cause(s) Sacrosanct?." ISASI forum, V. 25, #1, March 1992, pp. 8-9.
McNeill & Paul Freiberger, Fuzzy Logic. (New York, Simon & Schuster, 1993) [ISBN 0-671-73843-7]
Mill, A System of Logic, 8th ed. 1843.
(London, Longmans, 1873)
Perrow, Normal Accidents. (New York,
Basic Books, 1984)
Supreme Court opinion in the case of General Electric company, et al.,
Petitioner v. Robert K. Joiner et
Vaughan, The Challenger
Launch Decision. (University of Chicago
Press, 1996) [ISBN 0-226-85175-3]
. Technical Faculty, AG RVS, University of Bielefeld, D-33501 Bielefeld, Germany
. An example of WB analysis of the
American Airlines accident at Cali, Colombia, is available at (GeLa:97b).
a district court to admit opinion evidence which is connected to existing data
only by the ipse dixit of the
expert." (USSC:96) "Ipse dixit" =
"That which he says", or "Because I say so."
Thus the NTSB can assure the public that the
principal "Probable Cause" of General Aviation accidents is "Pilot failed to
obtain or maintain flying speed," not yet having parsed the syntax well enough
during 37 years to discover that its proclaimed cause factor is not a "cause"
at all; it is a description of what happened, and an incomplete one at that .