Tag Archives: international operations

The Injury of Pilot Fatigue: Is Fatigue a Stress or a Strain ?

Early morning sun rising through clouds.

Early morning sun rising through clouds.

Fatigue: Is It a Stress or a Strain, that is, an injury? Is fatigue an injury to the human body from which we need time to recover? Or is fatigue just being tired or over tired, a stress for which a good night’s sleep is the common remedy?

That is the question: is fatigue just a stress on the body and mind and as such something from which the body and mind can bounce back without any damage? Or is fatigue rather something more insidious and injurious than just a stress? Is it possible that fatigue is actually a strain, that is to say,  an injury, damage to the body and mind? If fatigue is an injury to the body and mind, an overstress resulting in a strain, does the body and mind need time to heal back to health from this injury? Is the time of a “good night’s sleep enough time to heal from this injury?

Does repeated stress lead to more damaging strain? Can the road to recovery from the strain of fatigue to the body and mind be a lot longer than just one good night’s sleep? Is the body and mind being damaged beyond the ability to recover in a day or a weeken

Human beings who has spent many nights and days working multiple shift hours far in excess of any reasonable eight or ten hour schedule can be over tired, falling asleep at the switch as the saying goes from fatigue. Yet they are there trying to do a good job, a necessary job and trying to have a life outside of work at the same time. The one thing that has not been discussed is does recovery from fatigue take much more time than just one good night’s sleep. If so, why? Is a person somehow injured in my mind and body to the extent that they need to heal? If so, where was the injury, how can a person feel it and how can they measure it? How much time is needed for full physiological recovery of body and mind? Is sacrificing the health of body and mind for a job well understood? If so, are people being separately compensated for both the work done and the sacrificing of the health of body and mind?

There are two issues to working at night and working extended hours repeatedly, the issue of compensation for the work and compensation for the hours past any reasonable shift.

But there are often more questions about fatigue than answers.  What is the pineal gland anyway and how does it work? Does the brain need oxygen and sugar to function? Why does worry have the same affect as caffeine? Why is a hot shower so refreshing when tired? Why do kids fall asleep when tired wherever they sit down? Why do older folks struggle often with sleep?  Why do flight crew often feel so tired on weekends that they just want to relax and do nothing stressful, just recover and hope for restful sleep? How and why does fatigue knock your brain out like a light switch turning off, even when you are not lying down in bed? How does it know to do that? What else do we not know about fatigue?

So, in my curiosity I harkened back to my university days studying metallurgy. We studied the physical relationship between stress and strain on a metal sample and on samples of wood, plastic, ceramics and other material. Stress is the force that is applied to the metal sample and strain is the amount of deformation that occurred to the sample piece as a result of the stress.

As students we found was that for the most part, metals deform elastically under lower levels of stress and essentially return to their original shape, size and strength. This means that the stress is bourne by the material and it springs back into its original being.

In physiology terms, we might say that one all-nighter isn’t so bad; just get a good night’s sleep and you will bounce back, good as new and be ready to go just fine. Probably all true, especially so for lab studies of human being subjects.

Now back to the metal samples. As we continued to add stress to the metal samples, somewhere down the line we got strain that is no longer elastic. The sample no longer bounces back. The sample now begins to deform. It is still strong and has some of its original strength, but it has become bent, stretched and weakened.  The stress that was put on the sample past the elastic strain point damaged the sample. It is deformed plasticaly, that is, it will no longer spring back into it’s original size, shape and strength. It is deformed into a new shape. It is still one piece, but deformed. It will not now nor ever go back into its original shape. Moreover, if the stress is continually applied, not only does the strain result in a deformation in size, shape and strength, the sample will eventually break, fail and just come apart, often with a very loud bang.

Now, back to the human physiology story. Again does the human body and mind react in a similar manner, that is to say, that the body and mind can take some stress, some sleeplessness, and bounce back elastically with just a good night’s sleep. But what happens to the human body and mind when the stress of sleeplessness is applied continuously and applied over the ability to take this stress undamaged?

Can the stress eventually cause a strain, that is, damage to the body and mind, damage that one good night’s sleep is insufficient in time and regenerative power to cause or allow a recovery? Can we over stress the body and mind with fatigue? Can fatigue be damage that affects the body and mind such that it is injured and needs time to recover from the injury? Is fatigue more than a stress? Can fatigue cause a strain or injury?

The answers to all of these questions is neither clear nor well known. But these questions need to be asked. Is fatigue more of a strain at some point than just a stress? Can we do injury to our bodies and minds by stressing them with fatigue to the point that they are damaged in some manner and no longer function well? Can this damage be such that one good night’s sleep is insufficient time in which to recover? Have we broken something that needs mending? Have we injured something in ourselves which needs recovery?

Is fatigue more of a strain than a stress?




UPS 6 Sept 2010 Dubai Crash GCAA Final Report: What Is the Cost of the Mishap? What Recommended Corrective Actions Will Prevent this Mishap from Occurring all over again?

100_4203What is not written in the just released GCAA Final Report of the September 2010 crash of UPS Flight 6? Was the report written for legal purposes or safety purposes? What wasn’t learned from the reading of the report? Was anything learned from the report that would have prevented this mishap, that wasn ‘t already known before the mishap? How does the line pilot become more safe as a result of this three year long exercise in investigatory procedure?

Is it possible that many people may ask these questions and feel that the report did not answer these questions? Here are a set of questions that may be on the minds of many people:

1. How did the cargo get on the plane, who put it there?

2.  How did it catch fire?

3. Why was this situation allowed to occur?

4. Were not all of the elements of this mishap known well ahead of time; did this accident happen once before and didn’t an investigation look into all of the essential elements of this mishap once before? Were not all these questions asked once before?

5. Why is it that this mishap happened again?

Again, these may be questions on the minds of many people who have read the GCAA Report and did not find all the answers to questions related to this mishap.  To look deeper let’s unwrap a few layers of information about the events related to this mishap.

First, the business of UPS is the main concern. According to their own published and filed financial reports, UPS created approximately $3.5 billion in operating income based on revenues of about $50 billion in 2010.  That is a return of about 7% or seven cents on the dollar for 2010 and about eight cents for 2011. So, this is good business return in this industry and appears consistent year after year.

Let’s consider the costs associated with crashing a fully laden B747-400 freighter and killing two crew. The plane is about $200 million. The cargo onboard guestimate is variable, but a fair estimate is between $50 million to $600 million, so let’s round off to $100 million. The crew death costs together all told about $2 million. The costs of a thorough three year investigation is about $5-6 million. Add this all together and the number is somewhere in the neighborhood of $308 million, and again since these are only estimates, the numbers could vary by plus or minus 10%.

Okay, now let’s figure based on seven cents to the dollar, how much business UPS has to conduct in order to have $308 million created as an operating income. The number is about $4.4 billion. Worth repeating: in order for this company to have enough money to go out and buy a B747, load it up with cargo, crash it, kill the crew and pay for a three year investigation, about $4.4 billion worth of business has to be conducted that results in $308 million in operating profits.

So what is the costs of a crash? How many people do you have to have out there working, selling service, moving packages, maintaining the operation, making things happen, so that at the end of the year they have all created $4.4 billion in revenue?

Asked another way, what is the comparison between the $4.4 billion and the annual revenue created by the entire company working the entire year of 2010, the year of the mishap? Comparing $4.4 with 2010 revenue of $50 billion, gives a number of about 9%. What does this mean? It means the mishap squandered the work of about 9% of the company’s entire work for one year. Again this is worth repeating. The UPS 6 mishap squandered about 9% of all the work done by all the UPS employees for the entire year.  That is a pretty big number in scale to any management goal and certainly a number acceptable by few responsible managers.

Put in another way, a company with 330,000 employees, where the work of 9% is wasted in a mishap, that would calculate to the work of about 29,700 employees wasted for one year.

While this is what happened, that set of numbers is not to be found in the GCAA report of UPS 6, nor is there any similar accounting of the costs of the mishap.

What was learned from the GCAA report that was not already known? The report identifies batteries of the lithium group carried as cargo to have been the source of the fire on board UPS 6.  But it was already known that lithium group batteries may initiate fires in cargo. It is already known that few methods of extinguishing are available to crews operating cargo aircraft and since there are no additional fire fighting crew members on board, any fire extinguishing that is going to be done, has to be done by flight crew members only. This means that either the crew keeps flying and no one fights the fire, or someone fighting the fire is not flying the airplane. But again, this was already known.  I am not sure what is in the GCAA report of the UPS 6 mishap, that was not already known? The report delineates the progress of the fire, the inability of the crew to complete a return to land, wherein the fire either diminished the systems needed to complete the flight or disabled or even destroyed them. Humans need oxygen to breath, the fire both filled the cockpit with smoke and caused the oxygen system to fail, just when it was needed most.

What was new in the report of the UPS 6 mishap that we learned? I am not sure that I found any thing new, anything that was not already known before. A cargo fire may render the cables controlling flight controls inoperable and do so rather quickly. That was not known, but is now. This is interesting because this aircraft is used for long overwater crossings regularly, wherein there is no divert field available without a transit time of two or three hours, meaning an immediate ditching, a ditching within 20 minutes of fire indication would be needed to complete any overwater ditching under controlled flight.

How is the line pilot safer as a result of the GCAA report? That appears open to discussion and to be determined. More fire suppression is good. Smoke hoods are good. All this is good, but preventing the event from recurring is the actual goal of the GCAA three year investigation. Other than chronicling the event per se, what else did the report do for safety of the line pilot? It is not really that clear.

Will the actions recommended in the GCAA report, if taken, prevent another similar mishap? If so, how would they? Will the actions keep Li group batteries off of aircraft? If so, how so? How much time will the next crew to experience a fire airborne have before they are overcome? Does this GCAA serve the safety of the line flight crew member? Did the report serve the safety purpose of mishap prevention for the benefit of the line pilot and the company or did the report serve the legal purpose of collecting the evidence for lawyers, regulators and administrators?

You are invited to read the report one more time and determine these answers for yourself. What additional questions come to your mind? What recommended corrective actions do you think need to be enacted in order to keep this same mishap from happening all over again? How can this mishap be prevented?

Captain Paul Miller preparing for a coming storm.