Fatigue

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Article Information
Category:	Aeromedical
Content source:	SKYbrary
Content control:	EUROCONTROL

Contents 1 Description 2 Hazards 3 Typical Scenarios 4 Contributory Factors 5 Solutions 6 Related Articles 7 Related OGHFA Material 8 Accidents & Incidents 9 Further Reading

Description

Fatigue is the general term used to describe physical and/or mental weariness which extends beyond normal tiredness.

Physical fatigue concerns the inability to exert force with ones muscles to the degree that would be expected. It may be an overall tiredness of the whole body, or be confined to particular muscle groups. Physical fatigue most commonly results from physical exercise or loss of sleep. Physical fatigue often leads to mental fatigue.

Mental fatigue, which may include sleepiness, concerns a general decrease of attention and ability to perform complex, or even quite simple tasks with customary efficiency. Mental fatigue often results from loss or interruption of the normal sleep pattern and is therefore of great concern to pilots and ATCOs, who are frequently required to work early in the morning or at night.

Sleep patterns are naturally associated with the body's circadian rhythms. Shift patterns and transit across time zones can interrupt circadian rhythms so that, for example, it may be difficult for flight crew or pilots on duty in the early hours of the morning or flight crew operating long-haul routes through multiple time zones to achieve satisfactory rest prior to commencing duty.

Hazards

Fatigue usually results in impaired standards of operation with increased likeliness of error. For example:

• Increased reaction time;

• Reduced attentiveness;

• Impaired memory; and,

• Withdrawn mood.

Typical Scenarios

In a pilot, fatigue may manifest itself by:

• Inaccurate flying;

• Missed radio calls;

• Symptoms of equipment malfunctions being missed;

• Routine tasks being performed inaccurately or even forgotten; and, in extreme cases,

• Falling asleep - either a short "micro-sleep" or for a longer period.

In an ATCO, fatigue may result in:

• Poor decision making;

• Slow reaction to changing situation;

• Failure to notice an impending confliction;

• Loss of situational awareness;

• Forgetfulness.

Contributory Factors

• Length of previous rest period;

• Time on duty;

• Physical conditions (temperature, airlessness, noise, comfort, etc.);

• Workload (high or low);

• Emotional stress (in family life or at work);

• Lifestyle (including sleeping, eating, drinking and smoking habits) and fitness; and,

• Health.

Solutions

Employers:

• Ensure that work schedules, including consecutive shift-working patterns, are constructed so as to have the least possible impact on off duty - and if applicable on duty) rest.

• Seek to provide optimum working conditions;

• Use Crew Resource Management or Team Resource Management training to promote awareness to fatigue and sleep issues.

Pilots and ATCOs

Adopt personal strategies which are likelt to decrease the effects of fatigue such as the following:

• Planning activities, meals, rest and sleep patterns during off-duty periods;

• Making the most of permitted rest breaks, including naps;

• Advising colleagues if one detects feeling drowsy;

• Alerting colleagues if they appear to be becoming drowsy.

Related Articles

• Pilot Workload
• Controller Workload
• Fatigue Management: Guidance for Air Traffic Controllers and Air Traffic Engineers

Related OGHFA Material

Briefing Notes

• Fatigue Manifestations (OGHFA BN)
• Sleep (OGHFA BN)
• Circadian Rhythms (OGHFA BN)
• Key Training Topics About Managing Jet Lag (OGHFA BN)

Visuals

• Fatigue and Alertness Management in Aviation
• Being Prepared for the Outbound Flight - Checklist
• Being Prepared for the Return Flight in Eastward Rotations - Checklist
• Being Prepared for the Return Flight in North and South Rotations - Checklist
• Being Prepared for the Return Flight in Westward Rotations - Checklist

Situational Examples

• Fuel Starvation, Stress, Fatigue and Nonstandard Phraseology (OGHFA SE)
• Impaired Judgment, Decision Making and Flying Skills due to Fatigue (OGHFA SE)
• Takeoff Weight Entry Error and Fatigue (OGHFA SE)

Accidents & Incidents

Events in the SKYbrary database which include fatigue as a contributory factor:

• MD82, Phuket Thailand, 2007 (LOC HF) (On 16 September 2007, an MD-82 being operated by One Two Go Airlines attempted a missed approach from close to the runway at Phuket but after the flight crew failed to ensure that the necessary engine thrust was applied, the aircraft failed to establish a climb and after control was lost, the aircraft impacted the ground within the airport perimeter and was destroyed by the impact and a subsequent fire. Ninety of the 130 occupants were killed, 26 suffered serious injuries and 14 suffered minor injuries.)
• E170, Cleveland OH USA, 2007 (RE HF) (On 18 February 2007, while landing at Cleveland Hopkins International Airport, USA, an Embraer ERJ170 overran the snow contaminated runway. The crew failed to execute a go-around at the minimum decision altitude (MDA) of the localizer approach when adequate visual reference was not available.)
• B738, Mangalore India, 2010 (RE HF FIRE) (On 22 May 2010, an Air India Express Boeing 737-800 overran the landing runway at Mangalore when attempting a go around after thrust reverser deployment following a fast and late touchdown off an unstable approach. Almost all of the 166 occupants were killed when control was lost and the aircraft crashed into a ravine off the end of the runway. It was noted a relevant factor in respect of the approach, landing and failed go around attempt was probably the effect of ‘sleep inertia’ on the Captain’s performance and judgement after a prolonged sleep en-route)
• AT43, vicinity Pristina Kosovo, 1999 (CFIT HF FIRE) (On 12 November 1999, a French-registered ATR 42-300 being operated by Italian airline Si Fly on a passenger charter flight from Rome to Pristina was positioning for approach at destination in day IMC when it hit terrain and was destroyed, killing all 24 occupants. A post crash fire broke out near the fuel tanks after the impact.)
• AT45, vicinity Sienajoki Finland, 2007 (LOC CFIT HF) (On 1 January 2007, the crew of a ATR 42-500 carried out successive night approaches into Seinajoki Finland including three with EGPWS warnings, one near stall, and one near loss of control, all attributed to poor flight crew performance including use of the wrong barometric sub scale setting.)
• … further results

Further Reading

EASA

• Moebus Aviation Final Report: Scientific and Medical Evaluation of Flight Time Limitations;

EUROCONTROL

• Fatigue and Sleep Management Brochure;
• Personal Strategies for Decreasing the Effects of Fatigue in Air Traffic Control;

UK CAA

• Aircrew Fatigue: A Review of Research Undertaken on Behalf of the UK Civil Aviation Authority.