RecommendationsRecommendationsfor the Work Hours offor the Work Hours of

UK Aircraft Maintenance PersonnelUK Aircraft Maintenance Personnel Simon Folkard D.Sc.

Chair: ICOH Shiftwork Committee

President: Working Time Society

Director: Body Rhythms and Shiftwork Centre

University of Wales Swansea

Remit from CAARemit from CAA

Assess the work hours of

Aircraft Maintenance Personnel

and produce recommendations

for “good practice”

4 4 Phases:Phases:

1. Survey Licensed Aircraft Maintenance Engineers.

2. Survey Employers & Contractors (mainly as check)

3. Review Literature on Safety and Fatigue.

4. Produce Recommendations for “Good Practice”.

Survey of A.M. Engineers.Survey of A.M. Engineers. Posted to all UK Licensed Engineers. 2210 returns (from c. 8000, i.e. 27.6%,

2093 analysed). Questions included:1. All aspects of Work Hours (Scheduled,

Normal, Minimum & Maximum).2. Sleep lengths3. “Risk” (sleepiness, mistakes, confidence)4. Physical health5. Interference/Advantages

Shift Systems in OperationShift Systems in Operation

>100 different shift systems.

5 main categories:Rotating shifts involving nights (32.5%)Rotating shifts without nights (30.2%)Permanent nights (9.1%)Permanent afternoons (1.4%)Permanent mornings/days (26.7%)

Hours Per WeekHours Per Week

Scheduled hours per week

Perce

nt

70

60

50

40

30

20

10

0

Normal hours per week

Perce

nt

40

30

20

10

0

Hours Per WeekHours Per Week

Maximum hours per week

Perce

nt

40

30

20

10

0

Length of Night ShiftLength of Night Shift

Maximum length of Night shift

Percen

t

80

70

60

50

40

30

20

10

0

Normal length of Night shift

Perce

nt

80

70

60

50

40

30

20

10

0

Hours before a BreakHours before a Break

Normal No hours before a break

Perce

nt

40

30

20

10

0

Maximum No hours before a break

Perce

nt

40

30

20

10

0

No. Successive Work DaysNo. Successive Work Days

Normal No successive work days

8 or more7654321

Perce

nt

50

40

30

20

10

0

Maximum No successive work days

8 or more7654321

Perce

nt

50

40

30

20

10

0

Sleep Duration on Different ShiftsSleep Duration on Different Shifts

Type of Shift/Day

RestNightAfternoonMorning/Day

No

rma

l Sle

ep

Du

ratio

n (

hrs

)

8.5

8.0

7.5

7.0

6.5

6.0

5.5

Sleep Before Morning ShiftsSleep Before Morning Shifts

Start time of Morning/Day shift

Sle

ep

Du

ratio

n (

ho

urs

)7.5

7.0

6.5

6.0

Review of Safety LiteratureReview of Safety Literature

Injuries and Accidents Can be “pin-pointed” in time.Can be related to specific features of

shift systems.

ButNeed large numbers, andOften the a priori risk is not constant!

Studies Across Three ShiftsStudies Across Three Shifts

Author(s) Industry Location Measure Number

Wanat (1962) Coal Mining Undergnd Injuries 3699

Wanat (1962) Coal Mining Surface Injuries 1328

Quaas & Tunsch (1972)

Metallurgic Plant

N/A Injuries 1577

Quaas & Tunsch (1972)

Metallurgic Plant

N/A Accidents 688

Levin et al. (1985) Manufacturing N/A Injuries 119

L. Smith et al (1994) Engineering Site 1 Injuries 2461

L. Smith et al (1994) Engineering Site 2 Injuries 2139

Wharf (1995) Coal Mining “Industrial” Injuries c.1970

Total c.13981

Risk Across Three ShiftsRisk Across Three Shifts

SHIFT

Night (22-06)Afternoon (14-22)Morning (06-14)

Me

an

RR

1.4

1.3

1.2

1.1

1.0

.9

Studies Over the Night ShiftStudies Over the Night Shift

Author(s) Industry Measure Number(8 hours)

Vernon (1923) Munitions Accidents 666

Adams et al (1981) Coal Mining Injuries 829

Ong et al (1987) Steel Mill Injuries 150

Wagner (1988) Iron Mining Accidents 775

L. Smith et al (1994) Engineering Injuries 902

Åkerstedt (1995) All Occupations Injuries c. 2500

Wharf (1995) Coal Mining Accidents 777

Macdonald et al (1997) Steel Manufacturing Injuries 774

L. Smith et al. (1997) Engineering Injuries 657

Tucker (2000) Engineering Accidents 274

  Total c. 8304

Risk Over the Night ShiftRisk Over the Night Shift

Time of Night

Me

an

RR

1.3

1.2

1.1

1.0

.9

.8

.7

.6

Studies Over Successive NightsStudies Over Successive Nights

Author(s) Industry Measure Number(4 Nights)

Quaas & Tunsch (1972) Metallurgic Plant Accidents 261

Vinogradova et al. (1975) Dockers Accidents 272

Wagner (1988) Iron Mining Accidents 442

L. Smith et al. (1994) Engineering Injuries 1686

L. Smith et al. (1997) Engineering Injuries 842

Tucker (2000) Engineering Accidents 286

Oginski et al (2000) Steel Mill Injuries 63

    Total 3852

Risk Over Successive NightsRisk Over Successive Nights

Successive Night Shifts

4321

Me

an

RR

1.5

1.4

1.3

1.2

1.1

1.0

.9

Studies Over Hours on DutyStudies Over Hours on DutyAuthor(s) Data Measure Total

Number

Akerstedt (1995) Sweden (1990/1) Lost time Injuries

(1+ days)

160,000

Haenecke et al (1998) Germany (1994) Lost time Injuries

(>3 days)

1,200,000+

Nachreiner et al (2000) Germany (1994-7) Fatal Injuries 2,000+

Folkard (1997)* Various Transport Operations

Accidents or SPADs

N/A

Total >1,362,000

* Based on several published studies

Risk over hours on dutyRisk over hours on duty

Hours on Shift

121110987654321

Me

an

RR

2.5

2.0

1.5

1.0

.5

0.0

How Can We MinimiseHow Can We MinimiseSafety Problems?Safety Problems?

1. Select and/or counsel individuals

2. Educate individuals regarding problems and coping strategies

3. Reset the clock (light/melatonin)

4. Improve shift systems

Recommendations forRecommendations for“Good Practice”“Good Practice”

Need to:1. Minimise the build up of fatigue over

periods of work. 2. Maximise the dissipation of fatigue

over periods of rest. 3. Minimise sleep problems and

circadian disruption

Daily LimitsDaily Limits

1. No scheduled shift should exceed 12 hours.

2. No shift should be extended beyond a total of 13 hours by overtime.

3. A minimum rest period of 11 hours should be allowed between the end of shift and the beginning of the next, and this should not be compromised by overtime.

Rest BreaksRest Breaks

4. A maximum of fours hours work before a break.

5. A minimum break period of ten minutes plus five minutes for each hour worked since the start of the work period or the last break.

N.B. “there is some evidence to suggest that frequent short breaks are more beneficial than less frequent longer ones”

Weekly LimitsWeekly Limits6. Scheduled work hours should not exceed 48

hours in any period of seven successive days.

7. Total work , including overtime, should not exceed 60 hours or seven successive work days before a period of rest days.

8. A period of rest days should include a minimum of two successive rest days continuous with the 11 hours off between shifts (i.e. a minimum of 59 hours off). This limit should not be compromised by overtime.

Annual LimitsAnnual Limits

9. Wherever possible, a total of 28 days annual leave should be aimed for and this should not be reduced to less than 21 days leave by overtime.

Limits on Night ShiftsLimits on Night Shifts10. A span of successive night shifts involving 12 or more hours of

work should be limited to 6 for shifts of up to 8 hours long, 4 for shifts of 8.1 to 10 hours long, and 2 for shifts of 10.1 hours or longer. These limits should not be exceeded by overtime.

11. A span of night shifts should be immediately followed by a minimum of two successive rest days continuous with the 11 hours off between shifts (i.e. a minimum of 59 hours off) and this should be increased to three successive rest days (i.e. 83 hours off) if the preceding span of night shifts exceeds three or 36 hours of work. These limits should not be compromised by overtime.

12. The finish time of the night shift should not be later than 08:00.

Limits on Morning/Day ShiftsLimits on Morning/Day Shifts

13. A morning or day shift should not be scheduled to start before 06:00, and wherever possible should be delayed to start between 07:00 and 08:00.

14. A span of successive morning or day shifts that start before 07:00 should be limited to four, immediately following which there should be a minimum of two successive rest days continuous with the 11 hours off between shifts (i.e. a minimum of 59 hours off). This limit should not be compromised by overtime.

Days notice of ScheduleDays notice of Schedule

15. Wherever possible aircraft maintenance engineers should be given at least 28 days notice of their work schedule.

Further Recommendations forFurther Recommendations for

“Good Practice”“Good Practice” (abbreviated)(abbreviated)

16. Employers of aircraft maintenance personnel should consider developing “risk management systems”.

17. Educational programmes should be developed to draw attention to the objective trends in risk.

18. Aircraft maintenance personnel should be required to report for duty adequately rested.

19. Aircraft maintenance personnel should be discouraged or prevented from working for other organisations on their rest days.

Conclusions:Conclusions:Shiftwork can result in reduced safety

(and increased fatigue).Shift systems should:

Minimise the build up of fatigueMaximise the dissipation of fatigueMinimise sleep & circadian disruption

Employers should develop “Risk Management Programmes”.