CHAPTER11 p.; Cause and Effect Analysis The cause an.docx

CHAPTER11
p.;
Cause and Effect Analysis
The cause and effect analysis is a structured approach to
determine the
causes and effects of events, which lead to the accident. There
are many types
of cause and effect analysis used in accident investigations, and
this book
will focus on the Apollo method (cause and effect process) and
the Ishikawa
Fishbone analysis ( developed by Kaoru Ishikawa) that the best
way to view the
causes and effects was to draw it out like a fish skeleton, with
the problem at
the head of the fish and the bones representing the causes.
Another view of
a cause and effect analysis is the "5 Whys" or "Questions to the
Void." The
5 Whys approach is to analyze the event to five levels (give or
take a couple)
until it is clear that the root cause is found.
The cause and effect approach is a structured approach, and
examining
the Apollo Method is based on (1) defining the problem; (2)
developing a
causal understanding of why the problem occurred (cause and
effect chart);
(3) identifying solutions; and ( 4) implementing and monitoring

effectiveness
of the best solutions (Gano 2007). For accident investigations,
the problem
has been identified, so for this approach, the only part discussed
will be the
cause and effect approach and the cause and effect chart.
117
P11rt Ill: Anab•timl Trchniquu
11 8
Cause and Effect Approach
The cause and effect analysis is best performed as a charc .
events and causal factors analysis or tree analysis. The k
s1Illilar to h
. . ey to the t e
effect analysts 1s che thought process of developing the effe
caus, •nd
and repeating that sequence. The process is the sam h cts of cau
. . e w ether . ses Apollo Cause and Effect, Ishikawa F1shbone,
or the 5 Wh using the ·th h ·d d ys analy · approach is to start
WI t e aca ent an analyze until • sis. 'l-1
1t reache th 'n,
factors . The approoch to this an alysis can be perfo d s e caus,i
rme on c software (Apollo 2011 ) or done on a sheet of paper h .
0 rnputer
. , w lteboard using adhesive nores. The benefit of a thorough

cau , or bi·
. . se and effe . keep analyzing unnl all causal fac tors are found
includin ct IS to
h · th · . g any sysr . causes, althoug many runes . e 1nvesugato
r will stop at th enuc
causes. e superficial
The approach to these three cause and effect analyses .
. are very Similar
Exlubit 11.1 displays the charnng structure for the three
approaches. ·
The Apollo Method is a software-based m ethod that leads th • .
e tnvesngator
through the approach with an effect followed by at least two
causes. Each
effect is "'caused by" a conditional cause and an action cause.
According
ro the Apollo method, "every time we ask 'why,' we should find
at leasr
ru-o causes and for each of these causes we should find at least
two more
causes resulting in four causes, and so on" (Gano 2008).
Normally the
chan is developed from left to right.
The fishbone diagram has been used for many years in business
and as a
quality rool for manufacturing. The diagram resembles the
skeleton of a
fish and focuses on the causes rather than the symptoms of a
problem.
The problem statement is the head of the fish along the fish's

backbone.
The ne..u step is the brainstorming or in case of an accident
investigation, the
facrs and analysis are analyzed to structure the big bones of the
fish that
are connected to the backbone (Ishikawa 1968). What areas of
the acciden<
investigation are the major types of causes? Some investigators
_use the
same major big bones such as people, policies, procedures,
eqwpmem,
and measurement, materials, and/ or environme nt. Others
change each
Chapter 11: Cause and Effect Anafysis
es of causes for the accident, such as lockout
the relevant typ . h Thi
" """n ID . . procedure and management overstg t. s wa5•- dure
uammg, ' . h
.,gou• proc~ 'm different and more specific to the accident;
owever,
-,kes each agra_ ti ier to start the process. Most fish bone
diagrams
1...- , is a lit e eas . k
,)le firS t wa) d ent on the right of the page and will actually
wor
.th the hea or ev h th fi h' ,..,. wt 1 f . however it really doesn't
matter whic way e s s bacJ.,,ar<ls w the e t, •
d · poinung.
he<
15

. thod of solving a problem or finding the causes of
5 Whys IS a me . • The t dly asking-at least five tunes-why the
problem, ·dent by repea e
an ,co .d t occurred and then why that cause occurred to explore
. oracoen . . h
esenr, d effect relationship and discover the causal factors (Haig
t
the cause an . f th h thi .
X'h,ile this is not a precise techruque as many o e ot ers, s IS an
2008). ·ct · · · h the effective technique if the investigator or
acct ent mvest:1gatton ~earn as
. th faces and analyses of the accident. This is not a technique
you use
m-<lepbemnning of the investigation, but only after
investigating and gaining
,i ihe ,,.---- . · al
much of the information and knowledge of the accident. As any
analyoc
,echnique, you must know the information before starting the
analyS1s.
While this technique is used by many individuals and many
comparues
around the world, it is also highly misused and the correct
causal factors
and corrective actions are not found, which doesn't correct the
real root
cause. One of the failures in this technique is by companies
forcing a "root
cause analysis" technique to be used by untrained investigators,
thinking
!hey are analyzing the accident better by using a technique.
Although this
seems to be a simple technique to learn and use, to be effective

it requires
!he same training, knowledge, and structure as any of the other
analytical
rrchniques, and as always, practice makes perfect. There is no
magic in the
number five, but the theory is that you must keeping asking why
until you
gtl 10 the root of the problem. This technique is very effective
if used by a
<earn 10 brainstorm and work through the analysis together.
The problem
"accident is placed at the top and is best used on adhesive notes.
The
why is repeated until the causal factors are found. This
technique is also
used ~o discover systemic causes at the bottom as well.
Normally this
•echruque Starts at the top and works down; however, it can
also be used
left 10 right.
l'"rt Ill· . A 11aly1fr,,/ T , .
8CfJl1Jq11e.s
120
Fishbone Diagram
~eople J
~ _l!kof
~~ures
1~--~ // Equipment ] [ Policies J
SWhys

Event
Why?
Why? Bad
Housekeeping
Chapter 11: Ca11st and Ejftd Ana!Jsis
cause and Effect Process
· to deterrnine the effect (event, accident, problem). In an
· ·· Thi . .
1n' . ·gacion the effect is the ace1dent, UlJury, or damage. s 1s
•dent lflvesu , . '"' f' er that effect is then analyzed by asking:
•'Why?"; •'What was this
,hefirSte ,e ' , • · ., b ,, ... or ''VhY did this happen?' to get to
the next level. This 1s then
ted until the causal factors are found. One of the issues with any
causal
c,,11SCU } · '
::~ analysis is knowing when to stop. If there is lack of
investigating or
1:n,wledge of the facts and analysis of the accident, then these
techniques
,ill not lead to the causal factors but will stop short and lead to
symptoms
of problems instead. Tbere are many types of problems that can
occur with
the cause and effect analysis, as listed in Exhibit 11.2.
Exhibit 11.2

;:::: PROBLEMS WITH,.c;AUSE Afilf EFFECT
• Stopping too soon (stopping at th
supert1c1al causes) e
• The need to place blame
• Not having enou h of the accident o;st~~owledge (facts)
analysis too soon ,ng the
• Not looking at all issues
(management pol'
supervision, t/aini~cy'
human factors des~g• ' n, etc.)
Exarnpl S Tu, e cenario
example scenarj
]
P<norrnin o has alread b
• •by in g a cause and y een analyzed b
ll"1 . rnosr accide . effect chart sh y some of th
)~cal techr,j nt investiga . ould be f . l e other techni
ques to find th Uons there is b' airy straightfo ques
e causal facto a tg benefit of _rward. This
rs. If using the 5 ~sing multiple
ys techni que,
121

Parl II/: Analytital I,,bniqueJ
122
the accident would be laid out similar to the tree analy ·
. s15 and WouJd shape. For purposes of usrng the technique,
let's do take that
a couple of . . of the 5 Whys. The top event would be the
individual fallin ueranons
Vhy did the individual fall off the ladder> Exhibit l l 3 di off
th• ladder.
th 5 Wh h . w n.. . thi . sp ays the s••-e ys tee ruque. w uen
usrng s technique, you will h ~, of
many iterations to get all of the causal factors . ave to per/onn
Exhibit 11.3
Event Falling off
ladder
.0.
Why? Ladder hit
by forklift
.0.
Why? Failure to
barricade aisle
Summary
There are three types of cause and effect analysis: Apollo
Method, fishbone
diagram, and the 5 Whys. Each of these techniques is a

structured approachw
stan with the accident and analyze it until it reaches the causal
factors. While
there are problems with this technique, if it is used by
experienced trruned
~ ve5rigators, these techniques are very effective at reaching
causal factors,
mcluding systemic causes.
*
Chapter 11: Couse a11d Ejftrl A11olysis
REVIEW QUESTIONS
d effect analysis?
es of cause an . ,
ethe three !'/P and effect analysts .
1.wttatar . three types of cause
he differences tn the
iWhatare t ctured approach?
J. wt,at is the Apallo method stru . fusing a cause and effect
analysis
blems orfatlures o
4 W,,ataresome of the pro
. such as the 5 Whys? . does the investigator
d ffect what questions
5. When analyzing a cause an e '
continually ask? A llo method and the
I the example scenario with the po 6. Continue to ana yze

fishbo ne diagram.
CHAPTER12
I ••r
Specialized and
Computerized Techniques
So far this book has discussed five major types of analytical
techniques:
events and causal factors analysis, change analysis, barrier
analysis, tree analysis,
and cause and effect analysis. Many other specialized analytical
techniques can
be used in accident investigations, and each has a role in certain
situations.
(NOTE: 1n some types of accidents, these specialized
techniques may yield so
much information and so many possible causes that the
investigator cannot
deal with them. The process becomes too confusing and
frustrating. The
mvestigator must learn to use the appropriate technique for each
type of
accident)
Some of the newest analytical techniques for accident
investigation involve
~-~oo d . all . . mputers an software. Some programs s!Illply ow
investigators
to portray a ·a · ·d cc, ents graphically, but others actually help
to analyze acc1 ents.

h " . d . e tee ruques range from computerized trees to fully
an!Illate
accident re . construction programs.
125
Part lll: At1u!) t1l"al Trrhm<J,m
126
Specialized Techniques
Time Loss Analysis
Time loss_ analysis ,~•as developed for the National Tran
Board. It 1s a graphical analysis tool that investigators
casportation Sifett
ro ~nderstand, de~'elop, an~ evaluate interventions and em: use
proacti"e:;.
~coons, ~nd r~acav~ly co give credit to good emergenc , re
tgency responst
1mervent10ns 1n accident situations. ) sponse effons or
Time loss analysis helps the investigator to evaluate how the _ .
em~ncy response or loss control actions affected the loss cau
llnung of
ac~dent and to analyze _the losses that occurred as the events
lea . sed hr the
acadeot progressed. It 1s useful in determining how 1 up to the
oss control mterv .
changed (or could have changed) the amount of loss a d h . .
enao~
n owumeincrcasea

~r decre~sed lo~ses ~r costs. It provides a way to analyze the
interventions
l.Il an acadent s1 ruat1on and determine how they changed the
course of the
accident sequence (SSDC 1987) .
To use this technique, investigators follow these seeps:
Discover and analyze all interventions that took place leading
up to
and during the accident.
Determine whether these interventions increased, decreased, or
had
no effect on the outcome (the accident sequence).
Forexample,ini
car crash with an injury, what is the effect o f the vehicle
having anti-lock
brakes? D o the brakes allow the car to sto p any sooner or in a
shorter
distance? What about airbags? What about crumple zones?
Assign a time value to each intervention. The time value can be
an acrw.l
number or a relative positio n on the chart. For example, the
brakes stan
to act as soon as the driver senses danger and applies them. The
anti-Jock
brake mechanism activates when the wheels begin to lock. The
air b~
activate at the moment of impact. The crumple zones crumple
after che
. . h damage to che
initial impact as the car continues to m ove, increasmg t e

car but distributing energy away from the passengers.
2!'.iiW
S
. f-,,ed and Computen'z.rd Tedmiqurs
Chapter 12: p,na1,
k d in dollars or units of
The loss axis is usually mar e b er of people injured ,
e the loss- d d or gas leaked, num
' p,.,i112.t ount of water £loo e
•• (iJll f . hides damaged). . c the simple car crash
I# o ,e al •sts chart ior .
n1,l!ll . wires a time loss an ) . fall three intervenoo ns-
£.tlubit 12.1 l~ lowest amount ofloss occurs t ed. Even if all
three
b(<labO'·e. e . and crumple zones-are us d th amount
. k br.ikes, :ur bags, if they are not use ' e
,h(·lflo-lOC ill be some damage; however,
¢ therew
i,'t , ,ill be much greater.
oioSSW
Analysis 11uman Factors al . and a human factors or
ri f h an factors an ysts,
1'1..- ire man}' methods o um al ' The basis of human factors
.. ~- h uld erform the an l ses. .
..oonomics expert s o p chin / w· orunent interaction and to
detemune .,- . tify human/ ma e en f
~'Sisis to1den : h d an effect on the accident. There is som e

type o
~ticther the intw.cnon a f cident The key is to determine the
involvement in all aspects o an ac . . ~= involvement and the
human capabilities to perform the task.
Exhibit 12.1
(
+
TIME LOSS ANALYSIS
TO - Driver senses danger
I _______ T 1 -Driver applies brakes I T 2 -Anti-lock brakes
deploy T 3 - Airbags deploy I, T 4 -Crumple zones crumple
t
~~ Natural : : : : , course of
: accident
9 : : Courseof
: ; l ~i~~d=l~t
: interventions
-~ ineffect
To T, T2 T3 T4
TIME
128
To ~ nduct n human/ machine / environment analysis

c.,-pc:.n tollm.vs these steps: of an accid
•n~ th
Analyze ho·w the human interacted with th '
e rnachin environment, etc. e, eqUiPrnen
Llst the bad interactions in the accident t,
- - sequence l
mter.1cao ns that do not favor the capabilities of the h · hese
are th
capabilities include physical interactions (stre h umf! a~ body.
I-I1.1rn '
. . . . ngt , ex,bi]j an
m~a~ n, eyesight, ~eann~, men~al tnteractions (knowled e ~•
ra~ge of
tr.11n1Ilg), and emononal mteracnons (morale mon· . g •
lrltelligence
, vanon, attitud •
Other types of human factors analysis analyze anthropome . e).
rk h · I cl · d · · try, btomechani ,vo - p ysio ogy, s ecnon an
traU11ng of personnel, job tasks and w ts,
In this of analysis, the focus i~ on the work environme~t that
orkloads.
bad beha"',or. The safety professional tries to eliminat th b
Produces
. . eeadbeh · instead of focusing on human error (Oakley and
Smith 2000). avior
Integrated Accident Event Matrix
An integrated accident event matrb. includes a list of all
individuals who
were at the scene of an accident and a time-based chart that

shows their
interactions (DOE 1999). This matrix allows an investigator to
analyze what
each individual was doing at the time of the accident. Although
the chan can
include any amount of time before the accident, it usually only
covers the ten
co twenty minutes before the accident occurred. This type of
matrix is helpful
for many types of accident investigations and is very simple to
perform. It is
a low-tech method of accident reconstruction.
To perform an integrated accid ent event matrix, the
investigator follows
these steps:
List all of the individuals who may hav e been involved in the
accident in
the left column of the matrix.
. d · h ' activities under Mark the next columns with umes, an
write eac person s ed
the appropriate time. Exhibit 12.2 illustrates an example of an
integrat
accident event matrix. ft shows that there was no interaction
ben~een the
. U d at the p1pefiner pipefitter and the mechanic and that the
supervisor ye e .
to get the job done as soon as possible, interrupting him.
Creaong an
Chapter 12: SperialiZJd and Co111puterized Tedmiqtm
. . a simple technique that can be used to

ed accident event macnx is
ji11ef1' . ns between people.
dis(O"er wceracno
odes and Effects Analysis .
failure M al . . sually used as a proacave safety tool d effects an
ys1s ts u
,,_:1,,re rnodes an . al al how failures can affect systems. The
r,.,i- - r rofesston s an yze . . d .
.,, help safe[) P d actively for accident invesogaaons an 1s ,.,
also be use re .d
ttChnique can I if the accident was caused by a system failure.
In acc1 ent
rs~ y.usefu all failure modes should be analyzed to determine
whether
J11rtsogat1ons,
Exhibit 12.2 C: INTEGRATED ACCIDENT EVENT MATRIX
Note: This technique is very helpful in fata l acciden~s
or other situations where some viewpoints are not available.
PEOPLE 10:01 10:02 10:03 10:04
Usf all people Record what
whocouldgive each worker
infomlotion was doing at
aboutinter- each time in
ocrionsand the sequence.
lttlp toanalyze
whatoc:curred
otthetimeof
rht ocddent.
Pipefitter Walked to job Turned to talk Went to Walked to

site with super- electrical box equipment;
visor and turned on found
breaker mechanic in
pain
Supervisor Talked with Yelled at Finished Finished
vendor pipefitter paperwork for paperwork
pipefitter
Mechanic Worked on Worked on Talked on Received equipment
equipment cell phone electrical
- shock
Part TT!: A 11a!Jtiral Terh11iq11es
132
Other Specialized Techniques
Expert Techniques
Some techniques that can be useful in accident investiga,-;
. uOnare b by e.,--pe.rts. E.,;:amples include: est Perfottned
Sofa,,ar, ha-:z.ard ana!Jrsis. Helps investigators to analyze f
so tware fail find causal fuctors in computer systems. llres '-nd
Common Cal/St faihm ana!Jsis. Used to find system failures th
. . . at led to accide
• Sneak amal ana!Jn.s. Looks at sneaks (failures) in a s nts.
ystem or circuit.

Failure Analysis and Structural Analysis
Failure analysis and structural analysis can be used for aca·d · .
ent mvesuga · ro determine types of failures and structural
flaws that led t . llons
o an acadent.
Sdentific Modeling
]Vlany types of modeling can be used to describe possible
accident scenarios or
ro sample data to reconstruct scenarios. These types of analysis
are performed
by experts who understand data collection and analysis
processes. Most of
these types of analysis are performed in a laboratory setting.
Acddent Reconstruction
Accident reconstructions may be simulated or computer-
generated. To
reconstruct an accident, the investigator finds out how each step
in the accident
sequence occurred. Once this sequence is determined, the
reconstruction
will help ro analyze the effects or potential effects of the each
event in the
sequence.
Computerized Techniques
Graphical Programs
. . Mi soft VisioTM and
lnvesogators can use graphical programs such as cro h alytical

h rts grap an CorelDRAWTM ro create events and causal factors
c a ' d effects
d ture cause an trees, draw barrier analysis summary charts, an
strUC
Chapter 12: Specialized a11d Computerized Tech11iq11es
s such as Microsoft PowerPoint™ and Corel ration program . .
, .. ....ens-Presen d t draw simple charts and analyocal trees.
While
ill'5'- rM can be use o . . . .
sent:1cions . all di play the results of the accident mvesogaaon,
p~ ms graphic y s . .
tJ,<SC progt" all analyze the invesogaaon.
d not actu Y tb<Y o
. al Programs
,Jlalyuc t ized programs however, can help accident b ed of
compu er , .
A new re . blem solving, investigation, and analysis. These
programs
·"'tors with pro . . b al ~res0o·· nl find causal facrors and
correcave acoons, ut so to be used not o y to
c,J al ses into written reports.
- ~m y . .
rograms have been designed for accident analysis,
Many custom p . 1 . U .
d 1 factors charting and analysis, and tree ana ys1s. smg - m= .
.. 1· am does not take the place of mvesogaong, ana yzmg,
,computer progr . . .

thi ki however. Four accident invesogaoon and problem solvmg
,nd n ng,
programs are:
, REASON® Root Cause Analysis by Decision Systems, Inc.
, Apollo Root Cause Analysis and RealityCharting™ by Apollo
Associated
Services
, TapRooT® System with SnapCharT® Software and Root
Cause Tree®
Software by System Improvements, Inc.
' RootCause LEADER™ Software by ABS Consulting, Inc.
The following short descriptions of the capabilities of each
program were
obtained from the companies' web sites. Web site addresses are
listed in the
bibliography at the end of the book.
REASON® Root Cause Analysis
The latest version of this root cause analysis software from
Decision Systems,
Inc. is called [email protected] 7.2. REASON® believes root
cause analysis should
be a validated and consistent process that discovers the root
cause of a
Ptoblem so th b · - f h at usiness pracoces can be used to
prevent recurrence o t e
('
0
_blem. One of the key features of REASON® is that it gives the

user a
thrailroad track to get you to the correct root cause." In other
words, it gives
e user th l
e too s to find the failure. The program leads the user to ask the
133
Parl III: A 11t1()'hcal Terlmiqu,s
134
right questions, and thus arrive at the e d . n pomt (
an e.,perc sys tem software tha t guides yo root cause) "t> . u to
uncov · ,,ea
your operaoons problems, enable you to er the r00 50n is .
manage and t cau
acoon plans and communicates the lesson learned track Your c
ses of
activities" (Decision Systems Inc. 2011) from Y0 ur probl
orrective ernso[ ·
111.is software is used not only for accide · . V!ng . nt
mvest::tgations
of problem so!V1.ng or process improvement. A vali . , but for
an
c.... ti · · . dat::ton ste . Y type son ,vare; us gives consistency
to the root ca al . Pis built in
d
use an ys1s pro to the

oes nor attempt to funnel the user into a sel cess. REAsoN
. . ect number of root ca r t
Other unportant funcnons are a correctiv . Uses. . . e act::ton
datab
correcove acoons and a searchable query for hin ase that track
searc g previ s
issues, root causes, and corrective actions. The ftw ous
accidents so are also h '
report editor. This program can be used for both . as a powerful
. . . . reacove and .
s1tuanons and combrnes rntegrated root cause anal . _proacuve
. ys1s, corrective ac .
tracking, and lessons learned. (Decision Systems Inc. 20l l) Uon
Apollo Root Cause Analysis
When Apollo Associated Services first started out it introduc d .
. ' e an approach
to basic problem solvrng that also works well for accident
investigation. A llo
has developed a very effective training program and cause-and-
effect pr!:ss.
The cause-and-effect process can be performed either on a
computer or
on paper. The process and a particular method of analysis is
Apollo's real
product. As the computer has grown to be a more important tool
in accident
investigation, Apollo has developed a variety of computerized
charting
programs. The newest is RealityCharting™.

RealityCharting™ is a graphical program that facilitates the
cause-and·
effect charting process. One of its features is the ability to drag
and drop
causes to any location on the chart. The software also provides:
• embedded Apollo Root Cause Analysis methodology
• detailed problem definition helps you understand sigiuficance
• graphic representation of interrelated causes and causal paths
• effective solution generation
• comprehensive reporting features
-I
S
. ,. ed and Co/Jlputerized Techniques
Chapter t 2: pee1a,1z
. nal user through the rules of the
,,,,ides the new or occas10 Jetion of a RealityChart (Apollo
0ndoW b- th rn roward comp if!I' d leads e
, ~tz ethod llfl ,,,,uo m . s 2011)-~, . red service
-~-o0a . .
o0'f® . two computerized accident invesngat1on
f1pB T®Systern consists of T e® These products are
Roo d R ot Cause re · d
,i,, fap SnapChar'f® an o . dhesive notes to chart events an
grams, t over using a h d pro irnprovernen . al gram that draws c

arts an
Jefini1ely an Char'f® is a graphic pro . li
., factors. Snap .fi . The result is a presentation-qua ty
~us~ modi 1cat1ons. d h
. ,.,ms and allows easy . h I investigators understan w at
,lii5•- Ch 'f® diagram e ps "The Snap ar d h ,, (Systems
Improvement
ch•rt- 1 . what happene to ot ers. happened and exp am
J 2011) ff
nc. ot Cause Tree® software picks up where SnapCharT® leaves
o • 'In~:~® detemunes what happened, and Root Cause Tree®
finds root
lnap ard develops corrective actions. 111.is software features a
Root Cause
~m C Tree®diccionary and a Corrective Action Helper®
module. The Root ause
Tre~includes a Human Performance Troubleshooting Guide that
helps
investigators ask the right questions to solve human
performance problems.
A built-in reporting feature and integrated databases ensure that
corrective
,ctions are tracked (Systems Improvement Inc. 2011 ).
RaotCause LEADER™ Software
RootCause LEADER™ allows accident investigators to
investigate and track
my l}pe of incident, event, or nushap. It can also perform data
trending and
ana!ys15, generate report forms, and include a detailed
background/ description
for each causal fact d >-rL: ftw . . . . or an root cause. , ms so
are can 1dent1fy root causes of

madents events · d • . . .
b
. • , acc1 ents, near nusses, reliability problems, quality
impacts,
or Ustness losses.
RootCause LEADER™ h . . . usino R C as five key features:
identifying consequences
-.,, OOt ause Ma TM hin '
recornrn d . P ' attac g photo files and other documents, tracking
en auons and tr d. Th Roo1ca M ' en ing. e consequence
categories and ABS's use apTM ar £ £
investigator identi e eatures or customizing the database and
helping the
fy root causes (ABS Consulting Inc. 2011 ) .
135
Part [] I: A nalytical T echnique,
136
Many specialized and
. . cornputeriz d
Summary
accident 1nvestigatio I e anaJyticaJ
h . n. n Order to technj

tee 111que, it rnust be c receive th que, <an b
per,orrned in th e IIlost inf e •std rnust be perforrned on[ b e
correq . . orlllati fo
1 . y y an expe ,, S!tuatton ,, on fro u sed for accident analysis b
. rt. <>1any syste~ . "'any re,, .. ~•
. . , ut cauaon h ... safety "'ll'!lrti gamed 1s useful. These anaJys
. s 0 uJd be used t ana.Jys,
8
, , _
th es rnay identify O ensu, ..,. be at rnay not be practical for th
.d . an overwhel-, e that th, ,. al . e ace, ent tn . "'ung "'ll an
ys1s and problem-so[v;~g p vesttgati
00
_.,,
. u, rograrns b •nenew to tnvestigators. are ecorning i . c
1. What does time loss analysis try to analyze?
2. Which techniques must be performed b
ncreastngl , .
l rn,Po"'n,
y an expert?
3. What does a failure modes and effects analysis look for?
4. What is the difference between a design criteria analysisand h
c angeanalysisl
5. How can computerized techniques be helpful in accident
investigations?

Part IV
< z
e
PREVENTING ACCIDENTS
D · d hich is the ultimate f, how to prevent future ace, ents, w .
art: :;~:~::cnting accident investigations. Determining the
accident
purpo d the causal factors prepares the accident investigator to
deterrrune
stljUence an · · hould
corrective actions that will prevent similar accidents. Correcuve
acuons s
be initiated, documented, and followed up (audited) to ensure
that they are
perfonning as intended.
Writing an accident report or filling out an accident form is not
simply an
exercise in paperwork. The report should document that the
facts and analysis
are correct, the accident sequence has been determined, and
corrective actions
have been developed to avoid recurrence of the accident.
Learning from accidents is one of the important aspects for
conducting
an accident investigation. Communicating the lessons learned,
preventing
systemic problems, and improving the safety programs are key
components
of learning from the accident. No accident should be repeated.
Objectives for Part IV:

Sheet1LegendStatus Report: Ending Period 2Early
StartDurationEarly FinishTask%
CompleteEVACPVCVSVIDA75%25Late StartSlackLate
FinishB50%12Cumulative Totals037000448C0446210Status
Report: Ending Period 4ATask%
CompleteEVACPVCVSV115551010212A100%35DFB100%240
55501010012Cumulative Totals059000B005538EStatus Report:
Ending Period 67210Task%
CompleteEVACPVCVSVA100%35B100%24C75%24D0%0E50
%10IDBudget0 123456789101112Cumulative
Totals093000A4010101010B3284848C4812121212Status
Report: Ending Period 8D1862226Task%
CompleteEVACPVCVSVE288812A100%35F402020B100%24T
otal2061814181420262226262020C100%32Cumulative1832506
484110132158160166186206D33%20E100%20Cumulative
Totals0131000Include your assessment here in this
sectionPerformance Index
SummaryPeriodEVACPVSPICPI2468EAC =VAC =
PJM6125 Project Evaluation: Earned Value Problem Set
Overview and Rationale
These problem sets offer an opportunity to practice using excel
to calculate earned value measures.
Program and Course Outcomes
This assignment provides a baseline understanding to the course

topics, and is directly related to
these course learning objectives:
LO5: Perform Earned Value analysis to provide both variance
and forecasting performance
measures for a simulated project
Essential Components
From Chapter 13 of the Gray & Larson textbook (7th edition),
complete Exercise 4 that starts on
page 489 and continues to 490. To submit your answer, utilize
the provided worksheet in Excel that
matches those found on pages 489-490 in Gray & Larson and
enter the missing data based on the
material provided.
Include an “Assessment” section at the bottom of your table that
refers to your calculations,
especially your EACf and VACf calculations: what is your
assessment of the current status of the
project? At completion?
and budget; to go above and
beyond, include details about various tasks that may impact

projected status)
If you have not done earned value before, this may take some
time to complete, so please be sure to
start early working on this assignment.
Complete all calculations in the designated cells within the
spreadsheet. Save the spreadsheet and
add your last name to the end of filename. Submit the file in
Blackboard.
Review the rubric below for grading information.
Submit your assignment via the Assignment Link as an excel
file type and via the TurnItIn
link below as a pdf file type).
Rubric(s)
Assessment

Element
Above Standard
(100-95%)
Meets Standards
(94.9 – 84%)
Approaching
Standards
(83.9 – 77%)
Below Standard
(76.9 – 70%)
Not Evident
(69.9 – 0%)
Excel
Calculations and
Data Entry
(75%)
Contains no errors in
data entry. Submits a
100% completed Excel
file for review
Contains <2 errors in
data entry. Submits a
100% completed Excel
file for review
Contains >2 errors in
data entry in either

file. Submits a
partially completed
Excel file for review
Contains multiple errors
in data (>5) entry and
submits an incomplete
Excel file for review
Files contains many
errors in data entry, is
not complete, or was not
submitted
Assessment
(25%)
Answers the two
questions in a thorough
manner, including any
notations about how a
late task may impact
other tasks, with
supporting data.
Answers both questions
in a full manner,
response could provide
additional insight and
supporting data
Answers both
questions in the most
basic manner without
providing additional
insight

Only partially addresses
one of the questions
Does not include a
Summary or Projection
SENSI
NOT MEAS UREMENT

TIVE
DDOE‐HDBK‐11208‐2012
July 2012
DOEE HAANDBOOKK
Acccideent andd Opperaational
Saafetyy Annalyysis
Volumee I: Acccideent AAnalyysis
Tecchniqques
U.S. Deparrtmennt of Ennergy
Wasshingtoon, D.CC. 205 85
DOE‐HDBK‐1208‐2012
INTRODUCTION - HANDBOOK APPLICATION AND SCOPE

Accident Investigations (AI) and Operational Safety Reviews
(OSR) are valuable for evaluating
technical issues, safety management systems and human
performance and environmental
conditions to prevent accidents, through a process of continuous
organizational learning. This
Handbook brings together the strengths of the experiences
gained in conducting Department of
Energy (DOE) accident investigations over the past many years.
That experience encourages us
to undertake analyses of lower level events, near misses and,
adds insights from High Reliability
Organizations (HRO)/Learning organizations and Human
Performance Improvement (HPI).
The recommended techniques apply equally well to DOE
Federal-led accident investigations
conducted under DOE Order (O) 225.1B, Accident
Investigations, dated March 4, 2011,
contractor-led accident investigations or under DOE O 231.1A,
Chg. 1, Environment, Safety and
Health Reporting, dated June 3, 2004, or Operational Safety
Reviews as a element of a
“Contractor Assurance Program.” However, the application of
the techniques described in this
handbook are not mandatory, except as provided in, or
referenced from DOE O 225.1B for
Federally-led investigations.
The application of the techniques described as applied to
contractor-led accident investigations
or OSRs are completely non-mandatory and are applied at the
discretion of contractor line
managers. Only a select few accidents, events or management
concerns may require the level

and depth of analysis described in this Handbook, by the
contractor’s line management.
This handbook has been organized along a logical sequence of
the application of the DOE “core
analytical techniques” for conducting a DOE Federal-, or
contractor-led Accident Investigation
or an OSR in order to prevent accidents. The analysis
techniques presented in this Handbook
have been developed and informed from academic research and
validated through industry
application and practice.
The techniques are for performance improvement and learning,
thus are applicable to both AI
and OSR. This handbook serves two primary purposes: 1) as the
training manual for the DOE
Accident investigation course, and the Operational Safety and
Accident Analysis course, taught
through the National Training Center (NTC) and, 2) as the
technical basis and guide for persons
conducting accident investigations or operational safety
analysisi while in the field.
Volume I - Chapter 1; provides the functional technical basis
and understanding of accident
prevention and investigation principles and practice.
Volume 1 - Chapter 2; provides the practical application of
accident investigation techniques as
applicable to a DOE Federally-led Accident Investigation under
DOE O 225.1B. This includes:
the process for organizing an accident investigation, selecting
the team, assigning roles,
collecting and recording information and evidence; organizing
and analyzing the information,

The term operational safety analysis for the purposes of this
Handbook should not be confused with
application of other DOE techniques contained within nuclear
safety analysis directives or standards
such as 10 CFR 830 Subpart B, or DOE-STD-3009.
i
i
DOE‐HDBK‐1208‐2012
forming Conclusions (CON) and Judgments of Need (JON), and
writing the final report. This
chapter serves as a ready easily available reference for Board
Chairpersons and members during
an investigation.
Volume II provides the adaptation of the above concepts and
processes to an OSR, as an
approach to go deeper within the contractor’s organization and

prevent accidents by revealing
organizational weaknesses before they result in an accident.
Simply defined, the process in this Handbook includes:
Judgments of Needs to Prevent
Re-Occurrence.
To accomplish this, we use:
Verification analysis.
Each of these analyses includes the integration of tools to
analyze, DOE and Contractor
management systems, organizational weaknesses, and human
performance. Other specific

analysis, beyond these core analytical techniques may be
applied if needed, and are also
discussed in this Handbook.
ii
DOE‐HDBK‐1208‐2012
ACKNOWLEDGEMENTS
This DOE Accident and Operational Safety Analysis Handbook
was prepared under the
sponsorship of the DOE Office of Health Safety and Security
(HSS), Office of Corporate Safety
Programs, and the Energy Facility Contractors Operating Group
(EFCOG), Industrial Hygiene
and Safety Sub-group of the Environmental Health and Safety

(ES&H) Working Group.
The preparers would like to gratefully acknowledge the authors
whose works are referenced in
this document, and the individuals who provided valuable
technical insights and/or specific
reviews of this document in its various stages of development:
Writing Team Co-Chairs:
id Pegram, DOE Office of Health Safety and Security
(HSS)
(LBNL)
Writing Team Members:
(NNSA)
e (ORO)
(BW-PTX)

n, Oak Ridge Y-12 National Security Complex
(Y12)
Advisor:
Technical Editors:
iii
DOE‐HDBK‐1208‐2012
iv

DOE‐HDBK‐1208‐2012
Table of Contents
INTRODUCTION - HANDBOOK APPLICATION AND SCOPE
................................................... i
ACKNOWLEDGEMENTS
...............................................................................................
............ iii
ACRONYMS
...............................................................................................
................................. xi
FOREWORD
...............................................................................................
.................................. 1

CHAPTER 1. DOE’S ACCIDENT PREVENTION AND
INVESTIGATION PROGRAM ............1-1
1.
Fundamentals..........................................................................
........................................ 1-1
1.1 Definition of an
Accident.................................................................................
...............1-1
1.2 The Contemporary Understanding of Accident Causation
.........................................1-1
1.3 Accident Models – A Basic
Understanding..................................................................1 -2
1.3.1 Sequence of Events
Model.....................................................................................
.............1‐2
1.3.2 Epidemiological or Latent Failure Model
............................................................................1‐3
1.3.3 Systemic Model
...............................................................................................
....................1‐4
1.4 Cause and Effect Relationships
....................................................................................1 -5
1.4.1 Investigations Look Backwards
...........................................................................................1‐

5
1.4.2 Cause and Effect are Inferred
.............................................................................................1
‐6
1.4.3 Establishing a Cause and Effect Relationship
......................................................................1‐6
1.4.4 The Circular Argument for Cause
........................................................................................1‐6
1.4.5 Counterfactuals
...............................................................................................
....................1‐7
1.5 Human Performance
Considerations.........................................................................
...1-8
1.5.1 Bad
Apples....................................................................................
.......................................1‐9
1.5.2 Human Performance Modes – Cognitive Demands
............................................................1‐9
1.5.3 Error Precursors
...............................................................................................
.................1‐11
1.5.4
Optimization...........................................................................
...........................................1‐13

1.5.5 Work Context
...............................................................................................
.....................1‐13
1.5.6 Accountability, Culpability and Just Culture
.....................................................................1‐15
1.6 From Latent Conditions to Active
Failures.................................................................1-16
1.7 Doing Work Safely - Safety Management Systems
....................................................1-18
1.7.1 The Function of Safety Barriers
.........................................................................................1‐2
0
1.7.2 Categorization of Barriers
...............................................................................................
..1‐22
1.8 Accident Types/ Individual and
Systems....................................................................1-25
1.8.1 Individual Accidents
...............................................................................................
...........1‐25
1.8.2 Preventing Individual Accidents
........................................................................................1‐26
1.8.3 System Accident
...............................................................................................

.................1‐27
1.8.4 How System Accidents
Occur......................................................................................
......1‐28
1.8.5 Preventing System Accidents
........................................................................................... .1
‐29
1.9 Diagnosing and Preventing Organizational Drift
.......................................................1-30
v
DOE‐HDBK‐1208‐2012
1.9.1 Level I: Employee Level Model for Examining

Organizational Drift ‐‐Monitoring
the Gap – “Work‐as‐Planned” vs.
“Work‐as‐Done”..........................................................1‐31
1.9.2 Level II: Mid‐Level Model for Examining Organizational
Drift – Break‐the‐Chain ...........1‐32
1.9.3 Level III: High Level Model for Examining
Organizational Drift ........................................1‐35
1.10 Design of Accident Investigations
..............................................................................1 -36
1.10.1 Primary Focus – Determine “What” Happened and “Why”
It Happened ........................1‐37
1.10.2 Determine Deeper Organizational Factors
.......................................................................1‐38
1.10.3 Extent of Conditions and Cause
........................................................................................1‐39
1.10.4 Latent Organizational Weaknesses
...................................................................................1‐39
1.10.5 Organizational Culture
...............................................................................................
.......1‐41
1.11 Experiential Lessons for Successful Event Analysis
................................................1-45

CHAPTER 2. THE ACCIDENT INVESTIGATION PROCESS
..................................................2-1
2. THE ACCIDENT INVESTIGATION PROCESS
................................................................2-1
2.1 Establishing the Federally Led Accident Investigation Board
and Its Authority ......2-1
2.1.1 Accident Investigations’ Appointing Official
.......................................................................2‐1
2.1.2 Appointing the Accident Investigation Board
.....................................................................2‐3
2.1.3 Briefing the Board
...............................................................................................
................2‐5
2.2 Organizing the Accident
Investigation..........................................................................
2-6
2.2.1
Planning..................................................................................
.............................................2‐6
2.2.2 Collecting Initial Site Information
.......................................................................................2‐6
2.2.3 Determining Task Assignments
...........................................................................................2‐

6
2.2.4 Preparing a Schedule
...............................................................................................
...........2‐7
2.2.5 Acquiring Resources
...............................................................................................
.............2‐8
2.2.6 Addressing Potential Conflicts of
Interest...........................................................................2‐9
2.2.7 Establishing Information Access and Release Protocols
.....................................................2‐9
2.2.8 Controlling the Release of Information to the Public
.......................................................2‐10
2.3 Managing the Investigation
Process...........................................................................2 -11
2.3.1 Taking Control of the Accident Scene
...............................................................................2‐11
2.3.2 Initial Meeting of the Accident Investigation Board
.........................................................2‐12
2.3.3 Promoting Teamwork
...............................................................................................
........2‐13
2.3.4 Managing Evidence, Information Collection
.....................................................................2‐15

2.3.5 Coordinating Internal and External Communication
........................................................2‐15
2.3.6 Managing the Analysis
...............................................................................................
.......2‐17
2.3.7 Managing Report
Writing...................................................................................
...............2‐18
2.3.8 Managing Onsite Closeout Activities
................................................................................2‐19
2.3.8.1 Preparing Closeout
Briefings.................................................................................
...2‐19
2.3.8.2 Preparing Investigation Records for Permanent
Retention .....................................2‐19
2.3.9 Managing Post‐Investigation Activities
.............................................................................2‐21
2.3.9.1 Corrective Action Plans
............................................................................................2
‐21
2.3.9.2 Tracking and Verifying Corrective Actions
...............................................................2‐21
2.3.9.3 Establishing Lessons Learned
...................................................................................2‐22

2.4 Controlling the Investigation
.......................................................................................2 -23
2.4.1 Monitoring Performance and Providing Feedback
...........................................................2‐23
2.4.2 Controlling Cost and Schedule
..........................................................................................2‐2
3
vi
DOE‐HDBK‐1208‐2012
2.4.3 Assuring Quality
...............................................................................................
.................2‐24

2.5 Investigate the Accident to Determine “What” Happened
........................................2-24
2.5.1 Determining Facts
...............................................................................................
..............2‐24
2.5.2 Collect and Catalog Physical Evidence
..............................................................................2‐26
2.5.2.1 Document Physical Evidence
...................................................................................2‐28
2.5.2.2 Sketch and Map Physical Evidence
..........................................................................2‐28
2.5.2.3 Photograph and Video Physical Evidence
................................................................2‐29
2.5.2.4 Inspect Physical
Evidence.................................................................................
........2‐30
2.5.2.5 Remove Physical Evidence
.......................................................................................2‐30
2.5.3 Collect and Catalog Documentary Evidence
.....................................................................2‐31
2.5.4 Electronic Files to Organize Evidence and Facilitate the
Investigation.............................2‐32
2.5.5 Collecting Human
Evidence.................................................................................
..............2‐34

2.5.6 Locating
Witnesses................................................................................
............................2‐34
2.5.7 Conducting Interviews
...............................................................................................
.......2‐35
2.5.7.1 Preparing for Interviews
..........................................................................................2‐3
5
2.5.7.2 Advantages and Disadvantages of Individual vs. Group
Interviews ........................2‐36
2.5.7.3 Interviewing Skills
...............................................................................................
.....2‐37
2.5.7.4 Evaluating the Witness’s State of Mind
...................................................................2‐39
2.6 Analyze Accident to Determine “Why” It Happened
..................................................2-40
2.6.1 Fundamentals of Analysis
...............................................................................................
..2‐40
2.6.2 Core Analytical Tools ‐ Determining Cause of the
Accident or Event ...............................2‐41
2.6.3 The Backbone of the Investigation – Events and Causal
Factors Charting .......................2‐43

2.6.3.1 ECF Charting
Symbols..................................................................................
.............2‐47
2.6.3.2 Events and Causal Factors Charting Process Steps
..................................................2‐47
2.6.3.3 Events and Causal Factors Chart Example
...............................................................2‐58
2.6.4 Barrier
Analysis..................................................................................
................................ 2‐60
2.6.4.1 Analyzing Barriers
...............................................................................................
.....2‐60
2.6.4.2 Examining Organizational Concerns, Management
Systems, and Line
Management
Oversight................................................................................
...........2‐65
2.6.5 Human Performance, Safety Management Systems and
Culture Analysis ......................2‐69
2.6.6 Change
Analysis..................................................................................
...............................2‐69
2.6.7 The Importance of Causal

Factors....................................................................................
.2‐76
2.6.8 Causal Factors
...............................................................................................
....................2‐77
2.6.8.1 Direct Cause
...............................................................................................
..............2‐78
2.6.9 Contributing Causes
.................................................................................. .............
...........2‐79
2.6.10 Root Causes
...............................................................................................
........................2‐79
2.6.10.1 Root Cause Analysis
...............................................................................................
..2‐80
2.6.11 Compliance/Noncompliance
.............................................................................................2
‐83
2.6.12 Automated Techniques
...............................................................................................
......2‐86
2.7 Developing Conclusions and Judgments of Need to
“Prevent” Accidents in

the Future
...............................................................................................
....................... 2-87
2.7.1 Conclusions
...............................................................................................
........................2‐87
2.7.2 Judgments of Need
...............................................................................................
............2‐88
2.7.3 Minority Opinions
...............................................................................................
..............2‐91
2.8 Reporting the
Results....................................................................................
...............2-92
2.8.1 Writing the Report
...............................................................................................
.............2‐92
vii

…
U . S . C H E M I C A L S A F E T Y A N D H A Z A R D I
N V E S T I G A T I O N B O A R D
INVESTIGATION REPORT
REPORT NO. 2007-04-I-WV
SEPTEMBER 2008
LITTLE GENERAL STORE – PROPANE EXPLOSION
(Four Killed, Six Injured)
Photo courtesy of West Virginia State Fire Marshal
LITTLE GENERAL STORE, INC.
GHENT, WEST VIRGINIA
KEY ISSUES: JANUARY 30, 2007
• EMERGENCY EVACUATION
• HAZARDOUS MATERIALS INCIDENT TRAINING FOR
FIREFIGHTERS

• 911 CALL CENTER RESOURCES
• PROPANE COMPANY PROCEDURES
• PROPANE SERVICE TECHNICIAN TRAINING
Little General Store September 2008
ii
Contents
EXECUTIVE SUMMARY
...............................................................................................
........................... 1
KEY FINDINGS
...............................................................................................
........................................... 3
1.0 INTRODUCTION
...............................................................................................
............................ 4
1.1 Summary
...............................................................................................
.......................................... 4
1.2 Investigative Process
...............................................................................................
........................ 7

1.3 Little General Store, Inc.
...............................................................................................
.................. 8
1.4 Little General Store Propane Suppliers
........................................................................................... 8
1.5 West Virginia Emergency Service Organizations
........................................................................... 9
1.6 Professional and Industry Organizations
....................................................................................... 12
2.0 INCIDENT DESCRIPTION
...............................................................................................
.......... 13
2.1 Events Preceding January 30, 2007
Explosion..............................................................................
13
2.2 Day of the Incident
...............................................................................................
......................... 14
2.3 Response to the Propane Release
....................................................................................... ........
... 17
3.0 PROPANE INCIDENT FREQUENCY
........................................................................................ 20
3.1 United States Hazardous Materials Incidents 2001 – 2006
........................................................... 20
3.2 Recent Propane Incidents

...............................................................................................
............... 21
4.0 PROPANE SYSTEM FUNDAMENTALS
.................................................................................. 22
4.1 Propane
Properties................................................................................
......................................... 22
4.2 System
Features.................................................................... ..............
........................................... 22
4.3 Propane Standards
...............................................................................................
.......................... 24
4.4 Propane Emergency Guidance
...............................................................................................
....... 25
5.0 INCIDENT AND EMERGENCY RESPONSE ANALYSIS
....................................................... 27
iii
5.1 Liquid Withdrawal Valve
...............................................................................................
............... 27

5.2 Propane Tank Placement
............................................................................................ ...
................ 30
5.3 Propane Service Technician Training and Response
.................................................................... 36
5.4 Fire Department Response
...............................................................................................
............. 41
5.5 911 Emergency Call Center Response
.......................................................................................... 44
6.0 REGULATORY ANALYSIS
...............................................................................................
........ 46
6.1 Occupational Safety and Health Administration
........................................................................... 46
6.2 Environmental Protection Agency
...............................................................................................
. 46
6.3 West Virginia Fire Commission
...............................................................................................
..... 47
7.0 FINDINGS
...............................................................................................
..................................... 51
8.0
CAUSES.................................................................................
....................................................... 53

9.0 RECOMMENDATIONS
...............................................................................................
............... 54
Governor and Legislature of the State of West Virginia
............................................................................ 54
West Virginia Fire Commission
...............................................................................................
.................. 54
West Virginia Office of Emergency Medical Services
.............................................................................. 54
National Fire Protection
Association.............................................................................
............................. 55
Association of Public-Safety Communications Officials
........................................................................... 55
Propane Education and Research
Council...................................................................................
............... 55
National Propane Gas Association
...............................................................................................
.............. 56
West Virginia E911 Council
...............................................................................................
....................... 56
Ferrellgas
...............................................................................................

..................................................... 57
REFERENCES
.................................................................................... ...........
............................................ 58
APPENDIX A FERRELLGAS INSTALLATION REVIEWS OF
THE INCIDENT TANK.................. 60
APPENDIX B 911 CALL AND INITIAL FIRE DEPARTMENT
DISPATCH ...................................... 63
iv
APPENDIX C RECENT PROPANE INCIDENTS
.................................................................................. 66
RECENT PROPANE INCIDENTS
...............................................................................................
............ 67
1.0 PROPANE RELEASE INCIDENTS
............................................................................................
67
1.1 Aberdeen, Washington
...............................................................................................
................... 67
1.2 Lynchburg, Virginia
...............................................................................................

....................... 68
1.3 Bristow, Virginia
...............................................................................................
............................ 70
2.0 PROPANE RELEASE AND FIRE INCIDENTS
......................................................................... 72
2.1 Sallis, Mississippi
...............................................................................................
........................... 72
2.2 Danville, Alabama
...............................................................................................
.......................... 73
APPENDIX D TABLE OF STATE REQUIREMENTS FOR
PROPANE SERVICE TECHNICIANS . 75
APPENDIX E UNITED STATES EPA - 40 CFR 311
............................................................................. 77
v
List of Figures
Figure 1. Aerial photograph of Little General store and
surrounding plot. ................................................. 4
Figure 2. Site plan of Little General Store.
...............................................................................................

... 6
Figure 3. Liquid withdrawal valve.
...............................................................................................
............. 15
Figure 4. Timeline of initial events
...............................................................................................
............. 17
Figure 5. Timeline of incident
response..................................................................................
................... 19
Figure 6. Typical ASME propane tank.
...............................................................................................
...... 23
Figure 7. Incident valve plug (Telltale
circled)........................................................................... ........
........ 27
Figure 8. Crack in valve
seal.........................................................................................
.............................. 29
Figure 9. Pre-incident photograph of the Ferrellgas tank.
......................................................................... 30
List of Tables
Table 1. U.S. hazardous materials incidents 2001-2006
............................................................................ 20

vi
List of Acronyms and Abbreviations
ASME American Society of Mechanical Engineers
APCO Association of Public-Safety Communications Officials
CETP Certified Employee Training Program
CFR Code of Federal Regulations
CSB U.S. Chemical Safety and Hazard Investigation Board
DOT U.S. Department of Transportation
EMS Emergency Medical Services
EMT Emergency Medical Technician
EOC Emergency Operations Center
EPA U.S. Environmental Protection Agency
FIR Ferrellgas Installation Review
HAZWOPER Hazardous Waste Operations and Emergency
Response
HVAC Heating, Ventilation, and Air Conditioning

IC Incident Commander
LP Gas Liquefied Petroleum Gas
MSDS Material Safety Data Sheet
NENA National Emergency Number Association
NFIRS National Fire Incident Reporting System
NFPA National Fire Protection Association
NIMS National Incident Management System
NPGA National Propane Gas Association
OES Raleigh County Office of Emergency Services
OSHA U.S. Occupational Safety and Health Administration
PERC Propane Education and Research Council
RESA Regional Education Service Agency
SCGM Service Center General Manager
STARS Safety and Training Administrative Records System
WVC West Virginia Code
WVCSR West Virginia Code of State Rules

1
Executive Summary
On January 30, 2007, a propane explosion at the Little General
Store in Ghent, West Virginia, killed two
emergency responders and two propane service technicians, and
injured six others. The explosion leveled
the store, destroyed a responding ambulance, and damaged other
nearby vehicles.
On the day of the incident, a junior propane service technician
employed by Appalachian Heating was
preparing to transfer liquid propane from an existing tank,
owned by Ferrellgas, to a newly installed
replacement tank. The existing tank was installed in 1994
directly next to the store’s exterior back wall in
violation of West Virginia and U.S. Occupational Safety and
Health Administration regulations.
When the technician removed a plug from the existing tank’s
liquid withdrawal valve, liquid propane
unexpectedly released. For guidance, he called his supervisor, a
lead technician, who was offsite
delivering propane. During this time propane continued
releasing, forming a vapor cloud behind the
store. The tank’s placement next to the exterior wall and

beneath the open roof overhang provided a
direct path for the propane to enter the store.
About 15 minutes after the release began, the junior technician
called 911. A captain from the Ghent
Volunteer Fire Department subsequently arrived and ordered the
business to close. Little General
employees closed the store but remained inside. Additional
emergency responders and the lead
technician also arrived at the scene. Witnesses reported seeing
two responders and the two technicians in
the area of the tank, likely inside the propane vapor cloud,
minutes before the explosion.
Minutes after the emergency responders and lead technician
arrived, the propane inside the building
ignited. The resulting explosion killed the propane service
technicians and two emergency responders
who were near the tank. The blast also injured four store
employees inside the building as well as two
other emergency responders outside the store.
2

The CSB identified the following causes:
1. The Ferrellgas inspection and audit program did not identify
the tank location as a hazard.
Consequently, the tank remained against the building for more
than 10 years.
2. Appalachian Heating did not formally train the junior
technician, and on the day of incident he was
working alone.
3. Emergency responders were not trained to recognize the need
for immediate evacuation during liquid
propane releases.
The CSB makes recommendations to the governor and
legislature of the State of West Virginia, the West
Virginia Fire Commission, the West Virginia Office of
Emergency Medical Services, the National Fire
Protection Association, the Association of Public-Safety
Communications Officials, the Propane
Education and Research Council, the National Propane Gas
Association, the West Virginia E911 Council,
and Ferrellgas.

3
Key Findings
1. The propane service technicians, emergency responders, and
store employees did not evacuate the
area as recommended by nationally accepted guidance for
propane emergencies.
2. A defect in the existing tank’s liquid withdrawal valve caused
it to malfunction and remain in an open
position.
3. The junior propane service technician who was servicing the
tank on the day of the incident had no
formal training and did not recognize the defect in the
withdrawal valve. He was also working
unsupervised, even though he had been on the job for only one
and a half months.
4. The placement of the 500-gallon propane tank against the
building’s exterior back wall provided
releasing propane a direct path into the store’s interior.
5. The Occupational Safety and Health Administration’s and
National Fire Protection Association’s
propane standards require training but do not include curricula,
practical exercises, or knowledge

evaluation.
6. 911 operators in the United States lack propane emergency
guidance to help them collect important
information from callers, offer life-saving advice, and convey
relevant information to first responders.
7. Firefighters in West Virginia are required to attend a
minimum of four hours of hazardous materials
emergency response training as part of their initial training
sequence, but refresher training is not
required. The responding Ghent Volunteer Fire Department
captain last attended a hazardous
materials response course in 1998.
8. Propane safety and emergency training is voluntary for fire
department personnel in West Virginia.
None of the responders from the Ghent Volunteer Fire
Department had specific propane emergency
training.
4

1.0 Introduction
1.1 Summary
At 10:53 am on January 30, 2007, a propane explosion leveled
the Flat Top Little General Store (Little
General) in Ghent, Raleigh County, West Virginia (Figure 1).
The explosion killed four and injured six.
The dead included two emergency responders (a fire department
captain and an emergency medical
technician, both from the Ghent Volunteer Fire Department) and
two Appalachian Heating propane
service technicians. The injured included the four Little
General employees who remained inside the
store, and two other Ghent Volunteer Fire Department
emergency responders.
Figure 1. Aerial photograph of Little General store and
surrounding plot.
5
The morning of the explosion, a junior propane service
technician1 (junior technician) from Appalachian

Heating was preparing to transfer liquid propane from an
existing tank owned by Ferrellgas to a newly
installed tank2 owned by Thompson Gas and Electric Services
(Thompson). The Ferrellgas propane tank
was installed in 1994 directly against the store’s exterior back
wall (Figure 2). At about 10:25 am, the
junior technician, working alone, removed a threaded plug from
the liquid withdrawal valve3 on the
Ferrellgas tank and liquid propane began flowing
uncontrollably. Liquid propane sprayed upward,
against the roof overhang, and dense propane gas accumulated
at ground level around the tank and the
foundation of the building. Over the next 25 minutes, the
escaping propane entered the Little General
store through openings in the roof overhang.
Shortly after the release began, the junior technician called the
lead technician to report the release and
seek guidance. At 10:40 am, the junior technician called 911 to
report the emergency and summon help.
A captain and two emergency medical technicians from the
Ghent Volunteer Fire Department were the
first to arrive, followed by the lead technician and two other
emergency responders. Shortly after their

arrival, the propane in the store ignited, leveling it and killing
two emergency responders (the fire captain
and one of the emergency medical technicians) and the two
Appalachian Heating propane service
technicians.
1 The report discusses the activities of two propane service
technicians: a junior technician, who had been
performing propane duties for one and a half months, and a lead
technician, who had been performing propane
duties for one and a half years. “Junior” and “lead” are used in
this report to differentiate the technicians’ relative
experience in propane service.
2 While commonly referred to as tanks, both of these were 500-
gallon pressure vessels. The American Society of
Mechanical Engineers (ASME) publishes the Boiler and
Pressure Vessel code; generally, stationary propane tanks
are considered unfired pressure vessels and manufactured in
accordance with Section VIII of the code.
3 The liquid withdrawal valve was a RegO Chek-Lok valve
model number 7572FC, which is no longer
manufactured. Although the RegO name is still used on
propane equipment, the company that manufactured this
valve is no longer in business.

6
Fire departments from the neighboring communities of Beckley,
Beaver, and Princeton responded to the
explosion. Later that day a team from the West Virginia Office
of the State Fire Marshal arrived to
investigate, assisted by an agent from the U.S. Bureau of
Alcohol, Tobacco, Firearms, and Explosives
(ATF).
Figure 2. Site plan of Little General Store.
7
1.2 Investigative Process
The CSB investigation team arrived at the incident scene on
January 31. They joined the Incident
Command structure, in accordance with the National Incident
Management System (NIMS),4 and began
on-scene investigation activities. On February 2, 2007, Incident
Command demobilized after the State
Fire Marshal concluded that the incident was not a criminal act.
The CSB investigation team remained,

and with the help of Little General management, protected and
preserved evidence, moving it to a secure
storage locker.
The team interviewed employees of the companies involved,
emergency responders, and officials from
the West Virginia Office of the State Fire Marshal; The West
Virginia Division of Labor; the Raleigh
County Building Department; Regional Education Service
Agency (RESA)5 Region I; the United States
Fire Academy; the ATF; the Beckley and Beaver, West Virginia
Fire Departments; the Occupational
Safety and Health Administration (OSHA); the National Fire
Protection Association (NFPA); the
National Propane Gas Association (NPGA); and the Propane
Education and Research Council (PERC).
In addition, the CSB tested and examined the valve that released
the propane from the Ferrellgas tank.
The test protocol included in situ examination and flow testing;
removal of the liquid withdrawal valve
assembly (valve, tank nozzle, and dip tube); photography and
examination of the valve and dip tube,
including removal of the dip tube; and dismantling and
examination of the valve.

4 NIMS is a comprehensive approach to incident response
management that provides a consistent, nationwide
template to enable all response entities to work in concert
during incidents. Implementation of NIMS is required
by the US Department of Homeland Security in accordance with
its authority in Homeland Security Presidential
Directive 5 “Management of Domestic Incidents.” The State
Fire Marshal reestablished an incident command
system following the explosion.
5 Enacted by the West Virginia Legislature in 1972, RESA
provides educational services to schools, including
technical, professional, operational, and programmatic services.
In addition to school-based programs, RESA
coordinates much of West Virginia’s professional firefighter
training program.
8
1.3 Little General Store, Inc.
Little General Store, Inc. operates 48 convenience stores
throughout southern and central West Virginia
and western Virginia. The Ghent store was a combination
gasoline station and convenience market. At
the time of the incident, the Ghent store and three others
included pizzerias, which used propane for

cooking.
1.4 Little General Store Propane Suppliers
1.4.1 Southern Sun
Southern Sun supplied propane to Little General beginning in
late 1994. Southern Sun was a family-
owned propane, heating oil, and ice supplier located in south
central West Virginia. In 1996 Southern
Sun sold its propane operations to Ferrellgas, which became the
supplier to Little General.
1.4.2 Ferrellgas
Ferrellgas, headquartered in Overland Park, Kansas, is the
second-largest propane marketer in the United
States, with offices and customers in all 50 states. One of
Ferrellgas’ business strategies is to “expand
operations through disciplined acquisitions and internal
growth.” Since 1986 Ferrellgas has acquired 166
propane distributors throughout the United States.
Late in 2006, Little General initiated a change in propane
suppliers from Ferrellgas to ThompsonGas
Propane Partners.
1.4.3 Thompson Gas and Electric Service, Inc.

Thompson is a privately held company that installs commercial
and residential propane systems and
delivers propane in the eastern and southeastern United States.
9
1.4.4 Appalachian Heating
Appalachian Heating is a family-owned heating, ventilation, air
conditioning (HVAC), and plumbing
company. Appalachian installs appliances, installs and
maintains heating and cooling systems, and
installs and repairs plumbing. Appalachian entered into a
contract with Thompson in August 2005 to
extend its business to include propane supply.
1.4.5 ThompsonGas Propane Partners, LLC
ThompsonGas Propane Partners is the limited liability company
(LLC) formed between Thompson of
Hagerstown, Maryland, and Appalachian Heating of Bradley,
West Virginia. Under the agreement
forming ThompsonGas Propane Partners, LLC, Appalachian

Heating provides personnel to install
propane systems and deliver propane; Thompson provides
equipment, bulk propane, and technical
support. The LLC has no employees.
1.5 West Virginia Emergency Service Organizations
1.5.1 West Virginia State Fire Commission
The West Virginia Fire Prevention and Control Act6 of 1975
established the West Virginia State Fire
Commission and granted the commission authority to
promulgate and establish a state fire code.7 The
commission established the National Fire Codes8 as the
minimum fire prevention and protection
requirements for the state.
6 West Virginia Code Chapter 29, Article 3 “The Fire
Prevention and Control Act.”
7 West Virginia Legislative Rule Title 87, Series 1, “State Fire
Code.”
8 NFPA publishes the National Fire Codes annually. The
National Fire Codes are a collection of all NFPA’s
standards.

10
1.5.2 West Virginia State Fire Marshal
The West Virginia State Fire Marshal’s Office, overseen by the
State Fire Commission, has four divisions
providing fire protection and regulatory services: regulation and
licensing, public education, fire
investigation, and regional response. The Fire Marshal enforces
the rules of the State Fire Commission
throughout West Virginia. Currently, the Fire Marshal’s Office
employs 12 code inspectors and 11 fire
investigators.
1.5.3 Raleigh County Emergency Services
An executive group is responsible for emergency services
management in Raleigh County, West Virginia.
Group membership includes county commissioners; the district
attorney; mayors of municipalities; the
county sheriff; the Office of Emergency Services (OES); and
the county public information officer.
Raleigh County emergency services encompass mutual aid
management among municipal fire
departments (career and volunteer); police; emergency medical
transport services; and community-based

support agencies. Services are coordinated under a unified
command system at the Emergency
Operations Center (EOC) located in Beckley.
Local municipalities are responsible primarily for emergency
response activities within their areas.
County resources are available from the OES and coordinated
through the EOC when emergencies exceed
local response capabilities. The OES develops and maintains
the Raleigh County Emergency Plan and
manages the county’s 911 emergency call center.
1.5.4 Ghent Volunteer Fire Department
The Ghent Volunteer Fire Department was incorporated in 1973
and has 28 members providing fire
fighting, life protection, and ambulance service to residents in
the Ghent area. Salaried Emergency
11
Medical Technicians (EMTs) are on duty at the fire station 24
hours a day, seven days a week.9 All
Ghent area emergency 911 calls are routed to the Raleigh

County EOC where operators dispatch the
appropriate fire or emergency medical service.
1.5.5 West Virginia E911 Council
West Virginia established the E911 Council in 1986 to organize
and implement the universal 911
emergency telephone number system. The council promotes,
researches, plans, educates, develops
funding streams, and proposes state legislation to ensure
reliable 911 call service operations.
Representatives from West Virginia’s 55 counties serve on the
council, which meets monthly.
The council works closely with emergency response industry
organizations including the National
Emergency Number Association (NENA) and the Association of
Public-Safety Communicators Officials
(APCO). In addition, the council is involved in activities to
promote and fund 911 systems statewide.
1.5.6 West Virginia Office of Emergency Medical Services
The West Virginia Office of Emergency Medical Services
(EMS) is a division of the West Virginia State
Trauma and Emergency Care System, administered by the West
Virginia Department of Health and
Human Resources. The Office of EMS was legislatively

mandated in 1975 and tasked with operating a
comprehensive statewide EMS program. It oversees licensing
for EMS agencies and training and
certification for responders.
9 The Ghent fire department comprises trained volunteer
firefighters and paid emergency medical technicians.
Many of the emergency medical technicians, including those
who responded to the Little General propane release,
also serve as volunteer firefighters.
12
1.6 Professional and Industry Organizations
1.6.1 National Fire Protection Association
The NFPA publishes consensus standards applicable to specific
industries and activities, including the
propane industry and hazardous materials incident response.
These standards, while voluntary unless
incorporated into state laws or regulations, …

CHAPTER10
Tree Analysis
Fault Trees and Analytic Trees
In tree analysis, investigators use a graphic display of
information to deductively
analyze a human, equipment, or environmental system and
determine paths
to failure or success. Tree analysis identifies the
interrelationships that led
to the accident and helps to develop causal factors (Department
of Energy
1999). Trees have been used in industry and government for
many years
in many different capacities. Two basic types of trees are used
for accident
investigations-fault trees and anafytic (developed) trees. Fault
trees show the actual
events of the accident, and they grow as events leading up to the
accident
are discovered. Analytic trees are used to compare the accident
situation to a
tree developed before the accident happened-usually one based
on an ideal
situation. Examples of analytic trees include Management
Oversight and Risk
Tree (MORT), Project Evaluation Tree (PET), and system
flowcharts.
Trees can be used in a variety of ways-as planning tools, in
accident
investigation analysis, in causal analysis, in project evaluation,
and in quantitative
analysis. In all of these applications, trees use deductive
reasoning-they start

witb a general "top" event and continue down to specific causes.
(Stephenson
1991)-Exhibit 10.l illustrates the tree structure.
103
,
::;rut>£ 'i:fi CT - z
Part Ill: Anol;•tzral Tecb111q11es
104
Exhibit 10.1
TREE STRUCTURE
General
Specific
About Tree Analysis
Three categories of trees are used to analyze various types of
problems:
• fault (negative) trees
• positive trees
• analytic (developed) trees.
These categories are illustrated in Exhibit 10.2.
Fault (Negative) Trees

Fault tree analysis was developed for the U.S. Air Force in
1962. Faulr trees
' ' i•to
are used qualitatively to determine failures in a system and
quanutaave l
bl I t S)'Srems, for determine failure rates. They are generally
used to trou es 100
h d • . . • · · (St phenson 199!). azar (nsk) analysis, and for
accident mvest1gat10ns e
Positive Trees
I . formation to
Positive trees display a system graphically-from genera rn ,s
tern;
• , , I vay to map S) · specific information. Creating an positive
tree ts a use u ' ' . . . ccs cin
. I · Posrttve lf components or provide information with a quick
grap ,re.
i
I •
This is O classic fault tree.1d .1 manual alarm clock cou . a,
in three ways-the clock ,s
faulty. the owner forgot to
wind it or the owner forgot to
set it. II any one of thes1; faults
occurs, the clock w,11 far/.
IES OF ANALY11CAL TREES

POSITIVE TREE
Run a
marathon
This example of a positive tree shows
that in order for on overoge person to
run a marathon, he or she must troln
and be injury-free. Training means
running long and short runs each
week; staying Injury-free means
stretching and eating healthy food,
ANALYTIC TREE
(MORT)
Supervision
less than adequate
(LTA)
Did not
detect/correct
hazards
Performance
errors
This Is an example of a portion of a topic for
"supervision less than adequate• (LTA),
Questions are asked to determine whether
eoc/J circle or rectangle Is LTA. For each
rectangle, more ques tions are asked, --------------------

IO!i
P,,rt Ill: A na/yhral Ttchniq11es
106
be developed early in the planning and d •
es,gn Sta
an accident occurs, and then used as anal . ges of a S)•
yuc trees if Stelll
accident occurs later by comparing the fai!u . and Vhe • b,r0 r
e or acc1d n a fail r,
(Stephenson 1991). ent to the 1 lire 0, P •nn,d
Analytic (Developed) Trees
tr,,
MORT, PET, and systems flowcharts are ex 1 . amp es of ana] ti
MORT is a safety system approach devel d y c trees.
ope by Bil]
Department of Energy in the 1970s and used . J 0 hns0 ,
extensive! • n •or th
1980s. It was developed as a proactive system safe t Y 10 the
1970 ' 'd . . . wn..:i . . ty oolandw I 'and aca ent tnvesnganon. w
,we 1t 1s still a viabl .d as ater . e acc1 ent in . l!sed;
tool, there 1s a shortage of individuals who kn h Vest,gati0 n a
0' ow ow to use . naiys~
an excellent tool to use after o ther analysis te h . It Proper! , 1 .
. c ruques have b ). t IS
to venfy that all areas have been properly m · . een compJ

vesugated 0ohn " '<l
PET was developed in 1988 by the U.S. Air F son 1973).
orce as a
approach that was simpler to learn and use th MO structured tt
an RT (Stephenson ,,
Other types of structured trees such as !JSfe fl h 1991).
, - , ms owe arts, can be us
a syseem s structure graphically. For accident • . . ed to sho,,
mvesugauons an i .
uses the tree to trace back through the system d find '
nvesngaror
an faults .
The Fault Tree Approach
The fuse seep in constructing a fault tree is to determ· h
. . _ . 1ne t e top evem.
For acadent mvesnganons, the top event is the accident · · d ,
tnJury, or amage
that occurred (Hammer 1993) . Events that had to happen in
order for the
accident to happen are listed on the next tier of the tree. Causal
factors-
fixable siruations or correctable areas-are on the bottom tier of
the tree.
The corrective actions the accident investigator recommends
will be geared
to fixing these problems.
Symbols and gates are part of the fault-tree diagram. The mosr

common
tree symbols and gates are illustrated in Exhibit 10.3. Since the
purpose of
this chapter is to describe how trees can be used in accident
investigations co
Chapter 10: Tree A nalysis
fault tree analysis methodologies and symbols that
al factors, di d . e ,nos, _ - vestigation are not scusse .
t1ettf111u1 ' to ncCident 1Il . -
0, ,ppl) . ediate" events m fault-tree termmology. Failures Jo fl
re "1nterm . .
,vents a . all diagramed under tntermediate events. Under each
fop are logic, Y . . .
,,esses h e may be other intermediate events (intermediate J- .
~mt~ ...
11edcace . be discovered as the mvesngauon goes on), basic
iitrt'fl conunue to .
cs n1'Y that stop the chatn), undeveloped events (events that ,.-
en al factors . .
. 0cs (caus .al bout which not enough 1s known to conunue the
tree), ,,t enn or a
;0coosequ ( nts that are normally expected to occur). For
example aJt _ 1 events eve ,
,0,1er<1"' din a hole and broke his leg, the broken leg is the top
o 1 yee steppe ;rane01P0 ,
5
next tier of events includes the intermediate events "hole
'fhe rree . · "G · c __ L ereoc. " d "employee not paying

attenuon. omg a step uu mer leads
[10,guarded an the answers to questions like "Why was the
employee not
b ic " 'eots-- d d," Th · · co as • ;, Why was the hole not guar e .
e mvestrgator must
. attenuon.
p,png f the accident scenarios in order to structure an accurate,
fully
,oaly1e all 0
dereloped analytical tree. . ..
· a fault tree are logically directed through gates (see Exhibit
10.3). Alleveots 10
d" means that all outputs must occur. For example, if the top
event lee "an gate
'. ding an e-mail, then to make that top event occur, the
computer must be
': 00 AND it must be connected to a phone line. Other things
may have to
cum fth dfircil An"" th 1,,ppen as well, but both o ese must e te
y occur. or gate means at
if anv one of the events on the second tier happens, the top
event will happen.
Foe ~,ample, if the top event is making a million dollars, then
to make it occur
)1lU could be a professional athlete OR win the lottery.
Once you determine the top event, the next step is to start tree
construction.
The uee construction steps for an accident are:
I. Define the top event (accident, injury, or damage).

2 Investigate the accident. (Learn about the system, the
management
structure, the accident, etc.)
3. Construct the tree. (Work from the top down asking why the
top event
occurred.)
l. Develop causal factors. (The basic events-the boetom tier of
the tree-
are causal factors.)
Pa11 Ill: A•alJliral T«bRiqm
The Analytic Tree Process
(Using MORT for Validation)
It is probably better to use MORT as a method of valid .
. . . . th . . •ling •noth
im·esnganon techruque an to use It as your pnmary techni ue er
t}'Pe of
to ensure that you did not nuss an area that should have b! ·. It
can help
and that the proper causal factors were determined If yo n
1nvestiga1'1J . . u consult th ' chart and find that some areas
were nussed, the investigati e »!OR1 . . . . on can con . your
invesnganon has been thorough, It will not take you Ion t tlnue.
lf
the MORT chart. g o cornple,,
Example Scenario
Once again using the forklift-ladder accident, part of a tree that

al thi .d . ill d . could be used to an yze s aca. ent 1s . ustrate m
Exhibit 10.7. The top event
is the warehouse supervtsor falling off the ladder. The next
level is the
forklift hitting the ladder, and the next is three ways that a
forklift could hit
a Ladder. The investigator asks questions about these three
reasons to arri,..c
at the bonom tier-basic events or causal factors: "Why did the
warehouse
supenisor not communicate what he was about to do to the
supervisor of
the night shift? Was his failure to communicate a training issue,
or did he
just decide to disregard the procedures? Why was the forklift
traveling ,ith
an obstructed view?" If the accident investigator docs not know
the answers
to these questions, he or she must interview witnesses, obtain
documents, or
perform tests to find the answers.
14
Chapter 1 O: Tree Analysis
. 7 E PROCESS FOR SCENARIO EXAMPLE
Part l/l: A nalytical Ttchniq11es
Summary
Many techniques are used in tree analysis . Each techni que

works b
for some rypes of investigation than for others, and some tech .
etter
. r f . . . mques ar
inappropnate ,or some rypes o mvest1gat1ons. The ma1·or b fi e
ene u of us·
tree analysis is that trees are, for the most part, structured eas t
mg . , Y o create and
easy to understand. You will be able to use one or more of thes
h .' e tee mques
to investigate almost every accident you encounter. (Please see
th A . e ppenclix
for a sample Analyncal Tree Flowcharr.)
REVIEW QUESTIONS
1. Which type of gate requires that all outputs must occur?
2. What are the three categories of tree analysis? Briefly
describe each.
3. What Is MORT?
4. What are the steps of tree construction?
s. Continue the analytic tree process for the example scenario
(Exhibit 10.7),
116
1
Course Learning Outcomes for Unit VI

Upon completion of this unit, students should be able to:
3. Apply accident investigation techniques to realistic case
study scenarios.
3.1 Develop a cause and effect diagram for an accident
investigation.
4. Evaluate analytical processes commonly used in accident
investigations.
Reading Assignment
Chapter 10:
Tree Analysis
Chapter 11:
Cause and Effect Analysis
Chapter 12:
Specialized and Computerized Techniques
Access the U.S. Department of Energy resource below, and read
the following sections: Cause and Effect
Relationships (pp. 1-5 to 1-7) and Analyze Accident to
Determine “Why” It Happened (pp. 2-76 to 2-86).
U.S. Department of Energy. (2012). Accident and operational
safety analysis: Volume I: Accident analysis
techniques. Retrieved from
https://www.standards.doe.gov/standards-documents/1200/1208-
bhdbk-
2012-v1/@@images/file
Centers for Medicare & Medicaid Services. (n.d.). Five whys
tool for root cause analysis. Retrieved from

https://www.cms.gov/medicare/provider-enrollment-and-
certification/qapi/downloads/fivewhys.pdf
Centers for Medicare & Medicaid Services. (n.d.). How to use
the fishbone tool for root cause analysis
Retrieved from https://www.cms.gov/medicare/provider-
enrollment-and-
certification/qapi/downloads/fishbonerevised.pdf
Unit Lesson
In this unit, we continue with our examination of techniques
that can be used to analyze the accident
sequence and to help determine root causes. You may ask why
we need so many techniques. Each
technique provides a slightly different view, and each can
reveal previously unrecognized facts. Each
technique also helps us determine which facts are not likely to
be causal factors.
In Arthur Conan Doyle’s book, A Study in Scarlet, Sherlock
Holmes and Watson are on a camping trip—
taking a break from the detective business. They had gone to
bed and were lying down, while looking up at
the sky.
Holmes said, ‘Watson, look up. What do you see?’
‘Well, I see thousands of stars.’
‘And what does that mean to you?’
UNIT VI STUDY GUIDE
Analytical Techniques II

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UNIT x STUDY GUIDE
Title
‘Well, I suppose it means that of all the planets and suns and
moons in the universe, that we are truly
the one most blessed with the reason to deduce theorems to
make our way in this world of criminal
enterprises and blind greed. It means that we are truly small in
the eyes of God but struggle each day
to be worthy of the senses and spirit we have been blessed with.
And, I suppose, at the very least, in
the meteorological sense, it means that it is most likely that we
will have another nice day tomorrow.
What does it mean to you, Holmes?’
‘To me, it means someone has stolen our tent.’ (as cited in
Ewell, 2012, p. 194).
Like Holmes, an accident investigator needs to be able to
identify the facts that are relevant and be capable of

disregarding those that are interesting but not useful. A good
accident investigator also learns how to identify
causes that go beyond the most obvious (such as human error).
Finding the deeper, root causes will lead to
more effective corrective actions.
Fault tree analysis is a structured technique that acts as a filter
for causal factors. The undesired event is
listed at the top of the tree. Once the accident is thoroughly
investigated, we determine, typically through
brainstorming, the events necessary to produce the top event. As
we continue to ask why something
happened, the tree branches out, revealing additional paths that
could lead to the top event. When there are
no more events, we have reached a root cause level (Oakley,
2012). A fault tree is an example of deductive
reasoning, where we start with a specific event and work down
to find the facts that support it. Inductive
reasoning starts with the facts and works upward to find a
logical conclusion. We used an inductive approach
when we developed the events and causal factors chart in Unit
IV.
We often think of Sherlock Holmes as using deductive
reasoning to solve crimes, perhaps because of his
propensity to use the word deduce. Holmes actually used a
combination of inductive and deductive reasoning
(Kincaid, 2015). So, too, in accident investigation, a
combination of approaches should be used.
Recall the accident scenario for Units IV and V where Bob
slipped and fell in a pool of water from a leaking
pipe. Click here to view a fault tree diagram developed from the
information in the scenario.
While much of the information is the same as contained in our

earlier change analysis and barrier analysis,
the fault tree does reveal some new factors that may require
further investigation and action. For example, on
the linked fault tree, one of the possibilities that could have
caused Sam not to place a warning sign was that
there were no warning signs available. A new branch of the tree
could be developed from this information,
and corrective actions could be identified.
The cause and effect process is another useful tool that, in
addition to identifying causal factors, ties the
factors to relevant categories, which will help in the
identification of corrective actions. When conducting a
cause and effect analysis, it is important to remember that
accidents have multiple causes, some more
evident than others. There is rarely a straight line cause and
effect relationship. Just because event B
happens after event A does not mean that event A caused event
B, even if it happens frequently. It is actually
easier to determine that there is no causal relationship (remove
event A, and see if event B still happens with
the same frequency).
The “Five Whys” technique and the fishbone (Ishikawa)
diagram both use the cause and effect process
(Oakley, 2012). In the Five Whys, we start with an event and
keep asking why until we reach an actionable
root cause. Returning again to our scenario involving Bob, it
might resemble the following:
on the floor.
leaking.

CHAPTER11 p.; Cause and Effect Analysis The cause an.docx

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