Fatigue

From SKYbrary Wiki

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• Withdrawn mood.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

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:

• GLF4, Teterboro NJ USA, 2010 (RE HF) (On 1 October 2010, a Gulfstream G-IV being operated by General Aviation Flying Service as ‘Meridian Air Charter’ on a corporate flight from Toronto International to Teterboro made a deep landing on 1833m-long runway 06 at destination in normal day visibility and overran the end of the runway at a speed of 40 to 50 knots before coming to a stop 30m into a 122m long EMAS installation.)
• AT43, Lubbock TX USA, 2009 (LOC HF AW FIRE) (On 27 January 2009, an ATR 42-300 being operated by Empire Airlines on a scheduled cargo flight from Fort Worth Alliance to Lubbock was making a night ILS approach in IMC to runway 17R at destination when it stalled and crashed short of the runway. The aircraft caught fire and was in any case effectively already destroyed by the impact. Both crew members were injured, one seriously.)
• B734, en-route, New South Wales Australia, 2007 (LOC HF) (On 11 August 2007, a Qantas Boeing 737-400 on a scheduled passenger service from Perth, WA to Sydney, NSW was about three quarters of the way there in day VMC when the master caution light illuminated associated with low output pressure of both main tank fuel pumps. The flight crew then observed that the centre tank fuel pump switches on the forward overhead panel were selected to the OFF position and he immediately selected them to the ON position. The flight was completed without further event.)
• DH8A, en-route, near Bristol UK, 2010 (AW LOC HF) (On 24 April 2010, a Bombardier DHC8-100 operated by Olympic Airways which had, some weeks earlier, been flown to the UK for heavy maintenance at Exeter was positioning from East Midlands to Exeter in day VMC with just the two flight crew on board when it experienced a significant oil loss from one engine en route and responded by shutting it down and declaring a ‘PAN’ to ATC for radar vectors direct to destination. The remaining engine was then found to be losing oil, and the declared status was upgraded to a MAYDAY and a successful diversion to the nearest suitable airfield, Bristol, was made.)
• FA20, vicinity Narsarsuaq Greenland, 2001 (CFIT HF) (On 5 August 2001, a Dassault Falcon 20, operated by Naske Air, on a non-scheduled international cargo flight, crashed on the final approach to runway 07 at Narsarsuaq, Greenland (BGBW), the aircraft impacting mountainous terrain 4.5 NM SW of the aerodrome.)
• … 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.