submission - Independent Pilots Association

lndicatioru and Effects of Fatigue
The massire ltrerarure on fatigue has identifred a numbcr of symptons that indicate thc presence
of fatigue. including: increased anxiety. decrcascd short ærm rnemory. slowed reaction tirnc.
decreascd work cffrciency, rcduccd morivational drivc. dccre¿sed vigilancc, incrcased variabiliry
in work pcrformance, incrcascd crrors of omission which increasc to commission whcn tinre
prcssure is addcd ro rhc rask, and increascd lapsc with incrcasing fatigtæ i¡ both numbcr and
äuration (Mohler, 1966: Dingcs, 1995). Many of thcsc syrnPtoms aPPcer ooly aftcr substantial
lcvcls of slecp dcprivuion havc bccn imposcd. A rcview of thc litera¡¡¡e tb¿ involvcd fatigue
lcvels likely to be cxpcrie¡ccd by pilots suggests that a conunon fatigtE slrnPtom is r change in
tbc lcvel of æptablc risk a¡ individr¡al will tole¡aæ'
Brown et al. (l97O) bad subjccs d¡ovc for for¡¡ 3-hor¡r sc^ssions. Tbc prformancc ræesurc uscd
was a count of thc numbc¡ of æcasioos in which thc subþt cxecutcd wh¡ thc cxperirncnær
considered a risþ passing r¡a¡ìcuver. \I/ben driving pcrformance bc¡pccn tbc lst aDd 4th scssions
werc comparcd. a 50% increåsc in th€ occurrencc of risþ passing rnaDcuvcrs in laær sessions,
when subjecrs $'ere Prcsullìåbly morc fatigucd, was obtaincd'
This change in tlre levcl of acccpøblc risk was confi.rrrrcd by Bartb a d. (1976) and
Shingledecker and Holding (1914) who found that fariguc caused subþs to cngage in greatcr
risk taking activiry in an cfforr to avoid additional cffort. In the Shingledcckcr and Holding srudy'
subjects pe rfornrcd 36 choicc-of-probabifiry (COPE) tasþ, which i¡volved locating a fault in one
of th'er remo\able ban-ks of one-wan rcsistors, eacb r¡'ith "'arying degrecs of probabiUry- that tbe
banli had farled. Twenry