No 1 Human Factors HSL Amended

8/10/2019 No 1 Human Factors HSL Amended

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Human Factors and Changing

perspectives

• “If this was March 22nd 2005 – the day

before the explosion – and I was

standing here addressing this audiencethe day before the explosion, my

remars to you would ha!e been much

different"#



Changing perspectives (2)

• “$my confidence in the %& 'roup(s safetyculture, safety standards, safety managementsystems and safety audit programmes would

ha!e been e!ident"#• “I(d ha!e pointed to some statistics – for

example, how in the pre!ious fi!e years thecompany had reduced its )*+ recordable

in-ury rate by almost .0 percent and its fatalityrate by .5 percent"#




• “I(d ha!e argued that this positi!e trend

reflected a concerted, systematic

approach to safety"#• “I(m sure I(d ha!e mentioned how

e!eryone woring in a %& facility is

empowered and expected to raisesafety concerns and to stop wor if they

thin conditions are unsafe"#




• “"" I would ha!e described our efforts to

continuously dri!e up safety standards

regardless of our impro!ing record"• $ on March 2/rd 2005 it became clear that

none of this was enough"#

John Mogford, 24 April 2006, Senior Group VicePresident, Safety & Operations, BP, CCPS Congress



Methods for Human Error Assessment

• he 1"" +ealth and *afety 3xecuti!e has

identified more than .0 methods

• /2 are rele!ant to Ma-or +a4ards• he next page lists some common ones and

then we mo!e into one of the simple

accepted methods



Common methods for Human Factor

(error) Assessment

• +uman 3rror ssessment and eduction

echni6ue 7+38

• echni6ue for +uman 3rror ate &rediction7+3&8

• *uccess 9ielihood Index Method 7*9IM8

•ecnica 3mpirica *tima 3rrori )peratori

73*3)8



HRA Assessment

• 1sing the +uman 3rror ssessment

and eduction echni6ue 7+38

• &re:processed + method

• ;irst published <=>5

• )ne of ?0 or so other + methods

• %ased on +uman ;actors literature



HRA accuracies achieved so far

• @0:>.A of all predictions within factor of <0 of

true !alue o!er range 0"0000< to <"0

• !erage .2A within factor of <0• !erage />A within factor of /

– irwan 7<==.8

– cf" for *ystems eliability ssessments, – @?A of predictions within factor of two,

=/A within factor of four 7*naith, <=><8



fter irwan, <==.



Understanding the method

• 'eneric as ypes 7'8

– +uman reliability is dependent on

the nature of the tas beingperformed

– 1nder perfect conditions the

associated le!el of reliability is fairlyconsistent

• 3rror &roducing Bonditions 73&B8

– May degrade reliability



eneric !as" !#pes (!!s)

;or example

• 78 otally unfamiliar tas, performed at speed

with no real idea of the liely conse6uences ofactions taen$ 70"558

• 738 outine, highly:practised, rapid tas

in!ol!ing relati!ely low le!el of sill$70"028

• 7M8 Miscellaneous tas for which no description

can be found$70"0/8



Error $roducing Conditions (E$Cs)

• /> 3&Bs described in +3

• 3xamples

– 1nfamiliarity 7x<.8

– ime shortage 7x<<8

– )perator inexperience 7x/8

– 1nreliable instrumentation 7x<"@8

• ssessment of how important each is



Human Fai%ure &cenario to Assess

&art of a procedure to establish the start

up of a piece of plantC

;ailure of )perator to establish rundown to

tanage 7set *plitter tower le!el control to

uto with 50A set point8 prior to addingheat to *plitter



Human Re%ia'i%it# Assessments

• 1nder “normal# conditions

• 1nder conditions that can degrade

human reliability



Fai%ure to esta'%ish rundon

(norma%* situation)

'eneric as ype

as ;C estore or shift a system to originalor new state following procedures, withsome checing – this tas is missionoriented and could include up to fi!e

discrete elements or actions, but wouldnormally only in!ol!e one basic acti!ity




(norma%* situation)

eneric !as" +omina% Human

Unre%ia'i%it#

!as" F ,-,,3




(Conditions affecting human re%ia'i%it#)

• Dot following procedures

• Do independent checing 7e"g" super!isor8

•1nreliable instrumentation

• Impo!erished 6uality of information 7e"g" shift hando!er8

• 1nclear allocation of function and responsibility

• Eisruption of normal sleep cycles

• )perator inexperience• 9ow worforce morale




Conditions affecting human re%ia'i%it#

eneric !as" +omina% Human Unre%ia'i%it#

as ; ,-,,3

Error $roducing Conditions

;actor otal +3 ssessed &roportion ssessed

ffect of ffect 7from 0:<8 ffect

&rocedures x2 0"> 72:<8 x 0"> F < G <">

Bhecing x/ 0"> 7/:<8 x 0"> F < G 2"@

Instrumentation x<"@ 0"? 7<"@:<8 x 0"? F < G <"2?

Impo!erished info" x/ 0"2 7/:<8 x 0"2 F < G <"?

Assessed nomina% %i"e%ihood of fai%ure

0"00/ x <"> x 2"@ x <"2? x <"? G ,-,24



Conditions affecting human re%ia'i%it#

Uncertaint# 'ounds

eneric !as" +omina% Human Unre%ia'i%it#

as ; 0"00/

Uncertaint# .ounds

0"000> – 0"00.

Assessed nomina% %i"e%ihood of fai%ure

0"00/ x <"> x 2"@ x <"2? x <"? G 0"02?

Uncertaint# .ounds

0"00@5 – 0"05.



A fundamenta% need

• as nalysis is a !ery important part ofunderstanding the potential for +1MD3)"

• ' opinion suggests that the potential formost error reduction can be achie!ed byactually understanding what the operatorneeds to do

• Mae the Hright way( the Heasy way( – reducingthe incenti!e to do it wrong, tae short cuts$



!e/as Cit#



Error Reduction

• Ban ' be changed

• elati!e importance of assessed proportionof affect of the 3&Bs

• Bost:effecti!e measures



Error Reduction

Bhecing

&rocedures

Impo!erishedinformation

Instrumentation

1nclear roles

*leep cycles

9ow morale

Inexperienced

operator



&ummar#

• 3xplained why +uman eliability ssessment 7+8 is important

• 3xplained how +uman 3rror ssessment and eduction echni6ue7+38 wors

•)utlined ey principles and e!idence

• Jored through some scenarios to aidunderstanding



HRA contri'ution from the H&0

Julie Bell and Jerry Williams

Hea%th and &afet# 0a'orator#

Harpur Hi%%

.u/ton1 &

5u%ie 'e%%6hs% gov u"

No 1 Human Factors HSL Amended

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