SAFE SKIES Fatigue, the enemy within
CAPTAIN A. RANGANATHAN
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Sufficient sleep and rest between long, multiple-sector flights is important to avoid the onset of fatigue in crew members. Are the stipulated rules being followed today?
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Two Sutras, I-30 and III-9, are very relevant to fatigue in aviation. Alertness and clarity of mind are very important in decision making.
Both accidents occurred at the end of a long duty period or at the end of a multiple sector flight and multiple duty days, when the crew were fatigued.
Photo: Department of Defence, USA
Heavy toll: The ill-fated Korean Air Flight 801.
Fatigue is the best pillow.
Benjamin Franklin
I am very tired. After this flight, I am going to take a week off”. These were the last few words of the captain of Indian Airlines flight from Bombay to Madras (As Mumbai and Chennai were called) on the night of October 12, 1976, just before he began the take off. A few minutes later the aircraft reached a fiery end, killing all on board. The captain had operated an early morning flight from Bombay to Delhi and back on a Boeing 737 aircraft. He was attending to the office work the whole day after arrival from Delhi. Late in the evening, he opted to operate the delayed Caravelle flight to Madras. He had been awake for more than 20 hours. Earlier in the week, he had been flying everyday and attending to office work. He was not tired. He was under extreme fatigue. His wrong actions to contain an on-board fire resulted in the crash.
Losing control
Twenty-one years later, on August 6, 1997, the Korean Air Flight 801 crashed on approach to Guam International airport, killing 228 and injuring 26 seriously. The cockpit voice recorder (CVR) evidence indicated that the captain was fatigued. At the beginning of the approach, the captain made unsolicited comments related to fatigue, stating “eh...really...sleepy.” The captain did not react to any inputs from the Ground Proximity Warning system or the calls from the co-pilot or the Flight Engineer. He flew the aircraft into the ground in what is called in accident parlance “A Controlled Flight into Terrain”.
Rafael Nadal was a tired man when he took to the court for the Australian Open finals against Roger Federer, on February 1. Thirty-six hours earlier, he had just completed a gruelling 5-hour-14-minute match against his semi-final opponent. When he won the finals after another gruelling match lasting more than four hours, he showed that an extremely fit human can be aroused to a very high level of performance even when he or she is tired.
The difference between tiredness and fatigue is detailed nicely by The Committee on Flight Time Limitations in the United Kingdom. “Tiredness resulting from physical or mental effort is a normal experience. Whilst tiredness may develop into fatigue, it differs from it in that a tired person can be quickly aroused to a high level of performance. We have come to consider fatigue as a markedly reduced ability to carry out a task. It is a condition of reduced performance from which there is no certainty that a person can be aroused in an emergency, even when considerable stimulus is present.”
Fatigue and its effect on the mind was known to ancient India through the teachings of the Maharishi Patanjali. The Yoga Sutras, written almost 2,500 years ago, have been explained in detail by my Yoga guru, Sri. T.K.V. Desikachar, the son of the great Yogacharya Sri.T. Krishnamacharya. Two Sutras, I-30 and III-9, are very relevant to fatigue in aviation. Alertness and clarity of mind are very important in decision making.
In their study of accidents involving domestic carriers between 1970 to 1998, the National Transportation Safety Board (NTSB), U.S., found decision making abilities suffered with long duration of time since awake (TSA) which was the dominant fatigue-related factor in these accidents. One conclusion was: “Half the captains for whom data were available had been awake for more than 12 hours prior to their accidents. Half the first officers had been awake more than 11 hours. Crews comprising captains and first officers whose time since awakening was above the median for their crew position made more errors overall, and significantly more procedural and tactical decision errors”. This finding suggests that fatigue may be an important factor in the airline accidents.
Affecting mental alertness
For high “time since awake” crews, the lower performance was a result of ineffective decision-making rather than deterioration of aircraft handling skills. These decrements were found on accidents involving short haul flights with a maximum of two time zones. There did appear to be two peaks in accidents: in the morning when time since awake is low and the crew has been on duty for about three to four hours, and when time-since-awake was high, above 13 hours.
A pilot’s level of alertness at any time depends upon a complex interaction between a number of variables. Four variables, in particular, need to be considered: time on task, time since awake, any existing sleep debt, and the pilot’s own circadian cycle. The sleep debt occurs over a period of time due to reduced sleep time from the normal 8 hours a day and effect due to the changes in sleep cycle due to changes in time zone etc. Even within the same time zone, when a series of flights are done with minimum rest period between flights, the sleep debt is likely to build up. A pilot is human and not a machine. One cannot switch off and on in a definite time frame.
Photo: Boeing
Benchmark case: The American Airlines Flight AA1420 that crashed in Arkansas.
Some symptoms of fatigue are similar to other physiological conditions, very similar to the effects of alcohol. Dr. Drew Dawson and Dr. Katherine Reid of Australia published a paper on fatigue, alcohol and performance impairment. They evaluated performance after 17 hours awake and found performance degraded to a level equal to that caused by a blood alcohol concentration (BAC) of 0.05 per cent. At 24 hours, performance decrements were equivalent to that of a 0.10 BAC. After 10 hours of sleeplessness, the decline in performance averaged 0.74 per cent per hour. In a recent study published by Lloyds TSB Insurance, they found that even a two-second sneeze resulted in a vehicle covering a distance of 62.6 metres while travelling at 112 kmph. During the critical phases of take-off and landing, aircraft speeds are around 250 kmph and any reaction time delay can result in a serious accident.
The age factor
Scientific studies have found that, with age, there is a significant decline in the duration of sleep at night due to increased night time awakenings. In older individuals, habitual night time sleep is accompanied by increased daytime fatigue, sleepiness, dosing, and napping. This increase in the number of sleep periods approximates normal sleep quantity and appears to indicate that sleep requirements remain the same over a person’s adult life time. These studies suggest that older crew members may have particular difficulties in achieving sufficient sleep as part of a normal duty schedule.
Other reasons for the low levels of actual rest achieved are due to the other activities that must be performed during the off-duty period. For pilots on layovers, these activities include getting to and from the hotel, meals, and personal hygiene. These activities clearly take away from the time available to sleep. Performance can also be affected by cumulative fatigue build-up across multiple days. Prof. Gundel in his study found that pilots flying two consecutive nights with 24 hours between flights slept about two-and-a-half hours less during their daytime layovers and experienced a significant decline in alertness on the second night flight. Alertness during the first six hours in both flights appeared to be the same. The latter part of the second flight showed lower levels of alertness. Spontaneous dozing indicated an increased susceptibility sleep. Subjectively, pilots felt greater fatigue on the second night. Therefore, with time since awake being the same, sleep quality and quantity during the daytime layover resulted in increased fatigue.
The incident involving Air India flight on the Dubai-Delhi-Jaipur-Mumbai route last June is a perfect example of this study. The crew had operated to Dubai via various airports, arriving at Dubai around 11.30 p.m. local time. The crew reached their hotel after clearing customs and immigration around 3.30 a.m. This equates to 6 a.m. in India. Their body clock, due to the circadian rhythm, would result in their sleep being curtailed. The crew had their call time around 9.30 p.m. to reach the airport to operate the flight. Both the pilots slept on the last leg, resulting in the aircraft overflying Mumbai by several miles. Fatigue overtook the crew. Did the airline, the pilot or the authorities learn from this? The answer is NO.
On January 8, 2009, the same captain had gone as an additional crew member to Dubai by the night flight from Delhi. He operated AI 690 from Dubai to Pune, departing at 1.35 a.m. and landing at Pune at 4.35 a.m. While landing, the aircraft fouled the arrester barrier at the landing end of the Pune runway. If was fortune, again, that saved another disaster. As it happens in Indian aviation, these are swept under the carpet. Lessons are not learnt or actions taken to prevent a recurrence. The effect of fatigue on aircrew is the least important aspect for our airline owners. This flight could have had a similar ending like the Korean Air 801.
During the last four years, violations of flight and duty time and rest period have been blatant. On March 8, 2006, a private airline flight on the Delhi-Mumbai-Bangalore-Chennai-Kolkata route, reached the destination at 9.30 p.m. The crew had been on duty for 11 hours and had flown for seven hours. The minimum rest that the crew required as per the rules was 16 hours. The pilots reached the hotel at 11.30 p.m. At 4 a.m., the co-pilot was woken up to operate the return flight, leaving Kolkata at 5.30 a.m. He had less than three hours rest as against the mandatory 16! The DGCA waived the rules to accommodate this serious breach of safety. What is shocking is the fact that there were several other instances when such waivers were issued to accommodate airline operators.
Benchmark cases
Aviation safety studies on fatigue had been in the forefront ever since the famous Korean Air flight 801 and the American Airlines flight AA 1420 which crashed in Little Rock, Arkansas. These two accident reports have become a benchmark for studies on accidents due to fatigue and wet runways. Both accidents occurred at the end of a long duty period or at the end of a multiple sector flight and multiple duty days, when the crew were fatigued.
Evan Byrne, head of the Human factors division of NTSB, identified three important factors in the AA 1420 accident: 1) Channelised thinking (concentrating on a single activity or thought); 2) Fixation and 3) Loss of initiative. In its investigation of the 1993 American International Airways accident at Guantanamo Bay, Cuba, NTSB noted that individuals often tend to underestimate their own level of fatigue. The commercial interests of airline owners and the greed of a small percentage of pilots lead to flights being operated by fatigued crew. Management pilots spending the day in office and carrying out a passenger flight with trainee co-pilots in the evening and night, endanger the lives of everyone on board. They should realise that the cost of an accident far exceeds the personal gains or corporate savings due to this breach of safety norm.
An aspect that is often ignored is the fatigue of maintenance crew and Air Traffic controllers. In India, we do not have any duty time limits or rest periods for any category other than pilots. Domestic operators do the maintenance of aircrafts between 11 p.m. and 4 a.m., when the circadian rhythm places the body at the lowest level of performance. Complacency is an off shoot of fatigue. Accidents have occurred because of a forgotten or incorrect maintenance action. A few seconds’ error by the ATC can result in a mid-air collision. These are issues that need to be addressed to make the sky safer.
Legal experts and airline owners in India are arguing that we have not had a fatal accident for several years and outdated regulations work well. Commercial interests are placed ahead of safety. Complacency is going to extract a heavy price. In the first week of March 2009, NTSB reiterated its commitment to rid fatigue in transportation industry, during the “Sleep awareness week”. While in India, for weeks, we are blissfully aware that we are sleeping over this important subject. Fatigue is a killer and the sooner we realise that, the safer will the skies be.
The author is an Airline Instructor Pilot on Boeing 737 with a flying experience of 20,000 hrs. He is also a Consultant for Wet Runway Operations Training and Accident Prevention.
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