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Not all the pressure to fly is from the boss. Although management pressures can be significant- pilots’ personal drive to perform can be enough to push them beyond the point of smart decision-making and safe flight. After all- canceling a flight because you’re tired — especially one that is work-related— is a tough call to make.

Dave Higdon   |   1st July 2006
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Dave Higdon Dave Higdon

Dave Higdon writes about aviation from his base in Wichita Kansas. During three decades in...
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Minding the hours is the key to safe decision-making and flight.

Not all the pressure to fly is from the boss. Although management pressures can be significant- pilots’ personal drive to perform can be enough to push them beyond the point of smart decision-making and safe flight. After all- canceling a flight because you’re tired — especially one that is work-related— is a tough call to make.

Yet- no higher stakes exist in aviation- as pilots have unfortunately found too many times. Tired is tired; exhausted is dangerous. And perhaps the most preventable of all accidents continues to plague general aviation precisely because of our reluctance to just say no and- often- our inability to recognize our impairment – because we’re too tired to accurately judge.

To illustrate- let’s take a look at a fatigue-related tragedy in Kansas- Wichita. It was just over two years ago- February 17- 2004- when a Beechcraft King Air flew into the ground while making a visual approach to Dodge City Regional Airport.

The Part 91 positioning flight for a medical EMS company departed Wichita at about 2:15 am CST for the company’s home base in Dodge City. After departing Wichita- the King Air climbed to 12-000 feet and proceeded westbound direct to Dodge City. About 30 minutes out the pilot reported Dodge City in sight- cancelled IFR and ATC cleared the flight for the visual approach.

Radar data revealed that the King Air descended on course to the airport while airspeed increased in parallel with the descent. Instead of completing the normal approach to the airport – on the northeast edge of Dodge City – the King Air passed north of town westbound until radar contact was lost with the aircraft about 4.7 nautical miles west of town at 3-200 msl. The aircraft never deviated from its westbound heading and the King Air impacted the ground about a minute later seven nautical miles west of the airport. The crash killed the pilot his two passengers- a flight nurse and flight paramedic.

The pilot lacked nothing in the way of experience and qualification: he held a commercial certificate- single-engine and multiengine land airplane ratings plus the requisite instrument rating. Of the pilot’s nearly 3-100 hours of flight time- 2-166 hours were in multi-engine aircraft and 666 hours in the King Air… 24 of those in the prior 30 days.

But during the 24-hour period prior to the accident- the pilot spent 14.5 hours on duty- had flown four of those – and had been awake for 21 hours straight.

According to the operating company's chief pilot- it was up to the pilot to determine whether he was within the duty and rest-time requirements. Under a Part 91- it was also the pilot's responsibility to determine if he was fit for flight. But lacking any other indication of mechanical problems and no radio transmission to the contrary- the National Transportation Safety Board concluded that the probable cause of the accident was the pilot's failure to maintain clearance with terrain because of fatigue.

Knowing when not to go
Without dissent- safety authorities view accidents due to pilot fatigue as among the most preventable – but they continue to happen all too frequently. And it can be particularly vexing for a corporate pilot and his employer to establish parameters for rest- duty and flight time when Part 91 operations impose no specific rules.

According to Part 91- it’s up to those who fly the aircraft to self-determine physical and mental fitness for flight. In other words: We self-certify every time we climb into the cockpit. There are signs that should key us in to the possibility that we’re too rest challenged to fly. General sleepiness; longer reaction times; decreased hand-eye coordination and shortened attention span are all indications of fatigue.

Only too often- though- pilots rationalize these symptoms as products of outside factors – work- family- recreational activities – and convince themselves that they’ll be fine once on the job; that they’ll overcome the fatigue and safely complete their flying duties.

Common sense and the observations of others might sway the pilot to make the unhappy decision to scrub off a flight. But ignoring what your body is telling you can be costly- in lives and hardware. Ignoring the problem all but assures it will continue- as it did in our 2004 case study.

Going on habit
Let’s look at another fatal accident to occur recently:

It’d been a long day for the crew of a Learjet 35A operated as an air ambulance by an Albuquerque company. They’d just dropped off a patient in San Diego. The pilot was more than 17 hours into his day- the co-pilot more than 16 hours; their duty day was already pushing 12 hours. Still- they were in compliance with company policies and flight-time rules for 135 operations – a more-stringent standard than what Part 91 operators face.

But when they launched into the night from Brown Field for Albuquerque the flight crew was already about three hours past their routine bedtime. All of this information is courtesy of the National Transportation Safety Board- which issued its final report on the October 2004 accident in late May.

Like Albuquerque- San Diego has some terrain issues pilots must deal with using Brown Field. But between their fatigue and incomplete information from departure controllers- the crew failed to take into account the terrain issues.

About one minute into the flight- controllers lost contact with the Learjet. As the NTSB put it- the crew were thousands of feet below the altitude needed to clear Otay Mountain after departing from Brown Field- and that’s where search crews found the wreckage - below the summit of Otay Mountain only a few miles from the airport.

Both flight crewmembers- a nurse- her EMT husband and another EMT died in the crash.

In its finding- the safety board said the air traffic controller failed to provide the crew instructions about clearing the terrain and did not advise the pilots of the minimum safe altitude for the night flight.

Acknowledging the wealth of information available about the terrain- however – from charts to approach plates – the NTSB found that the pilots' fatigue contributed to the crash. For all practical purposes- both pilots were already past the end of what would be a 'double shift' for other workers in critical posts- at 17.5 hours awake time for the pilot and 16 hours awake time for the co-pilot.

And their day had already included other tough legs- including the outbound leg from Albuquerque to pick up the patient in Mexico and the leg to deliver the patient to San Diego. Nighttime; an unfamiliar airport; a lack of complete information from ATC and fatigue enough to keep the pilots from noticing they weren’t climbing at a rate that would clear high terrain nearby.

This reads like the perfect climate for fatigue to be the final compounding factor in the scenario – the last mistake in a series.

Fatigue is cumulative
For years investigators and researchers have focused on fatigue as a human-factor item in accidents and the lack of rest is often considered to be at least a contributing factor in many aircraft accidents.

According to a technical memorandum issued in May 1996 by the National Aeronautics and Space Administration- losing as little as two hours of sleep will result in acute sleep deficit- which- in time- induces fatigue and degrades subsequent waking performance and alertness. The memorandum also suggests that sleep loss accrues into a 'cumulative debt' – something pointed out during last fall’s Bombardier Safety Standdown.

Fatigue need not be a result of flying or flight-duty time- either. Other activities away from the flight line and cockpit contribute just as readily when those activities contribute to a lack of rest for a flight-crew member.

In another accident investigated by the NTSB- the captain of a turboprop twin worked a long day- flying a day before the fatal crash in the winter of 2003. With no rest- the pilot followed the long flight day with a four-hour shift working as a nurse at a hospital near his home. His workday finally ended at 10pm. And at 8am the next morning- he started another flying day – only- this one ended with him in severe weather- off heading- off altitude.

The twin turboprop crashed in what investigators found was an accident due to the pilot’s lack of sleep and overwork. Supporting the investigators’ belief was a statement from a passenger on the flight the day before the accident. 'He looked like he was wiped out-' the passenger told investigators. 'He looked white in the face. I was concerned about it…' The witness also said the pilot complained about 'not feeling so good.'

For flight crew- the quality of off-duty time is every bit as important as the quantity. When off-duty activities generate additional pressure and strain and reduce rest time- pilots should know that they’re below par – even if they’ve technically met the spirit of rest-time policies.

And their bosses need to exercise enough oversight to be aware when pilots work second jobs – even part time.

Avoiding the ‘lack-of-rest’ blues
For decades- pilots flying under various rules – 91- 135- 121 – have used the same tool to gauge their alertness level and decide when they’re too tired to perform to their expectations: their own sense of fatigue. Unfortunately- self-examination hasn’t always worked out to be the optimal tool.

Humans are good at fooling themselves – and often they don’t realize how handicapped they are until it’s too late. But a software tool developed for the military holds potential to make these judgments more objective.

The Fatigue Avoidance Scheduling Tool (FAST) serves as a proactive tool for fatigue monitoring- putting the needed answer out ahead of trouble. Basically- FAST is a Windows-based fatigue analysis and forecasting software developed by NTI and Science Applications International (SAIC) for the US Air Force and Army- with support from the DOT.

Building on a fatigue model invented by Dr. Steven Hursh of SAIC- this computer tool makes fatigue predictions from inputs about the person’s sleep- activity- fatigue and task effectiveness. Hursh serves as a professor of behavioral science at Johns Hopkins University School of Medicine.

The SAFTE model – Sleep- Activity- Fatigue and Task Effectiveness (SAFTE) – received a broad scientific review and the Department of Defense considers the model an accurate- practical fatigue model for aiding operator scheduling in many activities. The DOT is conducting a three-phase examination of the model in the hopes of proving and calibrating it for use in avoiding excessive fatigue in transportation operations.

Now available for commercial applications- the FAST scheduling tool employs the SAFTE model to compare schedules in terms of predicted performance effectiveness. FAST uses entry of proposed schedules and generates graphical predictions of performance- as well as tables of estimated effectiveness scores for objective comparison.

Models such as this and others offer operators a 'snap gauge' for weighing pilot fatigue and performance potential that also serves to provide a graphic look at the way the pilot spends time on and away from the job – useful for getting pilots more in tune with the impact on their performance of how they live their lives.

In England- the Centre for Human Sciences at British aerospace and defense research group Qinetiq previously developed software designed to assess and predict crew fatigue for any given set of flight operations. The system for aircrew fatigue evaluation (SAFE) was created with the support of the UK Civil Aviation Authority.

Regardless of the name and origin- the importance of fatigue in flight safety can get no better highlight than from the number of efforts under way to resolve the problem.

The judgment call
Perhaps the most insidious aspect of fatigue is not all that’s visible – until it’s too late. And that aspect isn’t readily apparent because it’s a cumulative effect. We’re talking about judgment – or- actually- the lack of it.

When fatigue begins to influence our judgment we’re already making mistakes. Now- no aviation accident in my memory occurred because of a single mistake or bad call. In almost every case the accident finally happened as the culmination of multiple mistakes or misjudgments… which is where the insidious nature hits home.

The pilot doesn’t realize that fatigue is influencing command decisions; a mistake is followed by another oblivious misjudgment- and then another. Even seasoned observers might not notice the problem until several small mistakes begin to snowball toward disaster.

So setting and adhering to rest and duty-time policies is an operator’s best insurance against a tragedy – a tragedy that needed only extra sleep to be avoided.

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