New Ideas on AF 447 Stall Recognition & Stall Recovery Procedures

AF-447 Stall Recognition:

Were the Air France 447 Airbus 300-200 flight crew members trained in stall recognition by:

A) Angle of Attack (AoA) based stall warning alarm system or

B) Loss in altitude, as displayed on the altimeter, due to loss of lift?

C) Both A and B

D) Neither A nor B?

1. A stall of relative wind flow over the Airbus 330 wing occurred at Stall AoA, setting off the flight crew cockpit stall alarm system. The stall warning signaled that the AoA had increased above the Relative Wind Flow Stall AoA, and by aerodynamics, the wing was no longer producing enough lift for flight, and so the altimeter was unwinding rapidly, telling the flight crew that the aircraft was descending. But did the flight crew see the loss of altitude as a symptom of trouble, or the exacting cause of the trouble and their cue to enact stall recovery procedures? If they understood the loss of altitude as their cue that they were in a stall, why did they not immediately begin stall recovery procedures, such as lowering their nose attitude? I do not think that the other multiple alarms and warnings confounded the flight crew. I think that they did not see the unwinding altimeter as the stall recognition cue. If they did, they would have lowered the nose at 37,000 feet and resumed level flight. What was the confusion therefore, that confounded the AF 447 flight crew?

2. Is not the altimeter a very good and reliable indicator of a stall? Along with the AoA Stall Warning system, didn’t the flight crew have this very reliable and verifiable stall indicator, all the indication that they needed to solve their problem? Without a doubt, a rapidly decreasing altimeter is a very good stall indication, especially when the crew has nose up control inputs. Acting on that information alone, the crew would have been able to carry out published stall recovery procedures of lowing the nose to lower the AoA.

Altimeter in Stall Recognition

3. I would argue that, as the Air France Airbus descended from above 37,000 feet to the surface of the sea, loosing its altitude due to loss in lift,  the flight crew never recognized that the loss of altitude was their stall recognition cue. As a result, the crew never attempted standard operating procedure stall recovery by lowering the nose. Was the reason that the flight crew never realized that they were in a stall, due to the fact that they did not understand that the decreasing altitude as displayed on their altimeter, was the stall indication? Why was that the case for AF447? Is that still the case today at many commercial airlines around the globe?

4. From their stall recognition and stall recovery training at Air France Airbus training program, were the flight crew trained to recognize and recover from stall based only on the installed AoA-based stall warning system? Did AB and AF not require the altimeter as the next instrument to be checked for decreasing altitude, in the stall recognition and recovery procedure? How many other commercial pilots are their out flying the line, that do not understand stall recognition and stall recovery procedures?

5. Once a stall is recognized by observing the decreasing altitude on the altimeter, wouldn’t the next procedure in stall recovery be the same procedure of decreasing the nose attitude, just as in the case for stall recovery for AoA based stall warning? In the altimeter case, doesn’t the altimeter substitute for the AoA-based stall system for the stall recognition? Since the AF 447 flight crew never attempted stall recovery procedures, is it correct to conclude, that they never recognized that they were in a stall at all?

6. Should Air France, all airlines flying Airbus, and Airbus Training, and perhaps all commercial airlines, shift stall recognition and stall recovery procedures from focusing solely on AoA-based stall warning for recognition and reaction, and rewrite procedures and redirect training to include scanning the altimeter for loss of altitude, as part of the procedures for stall recognition and stall recovery? Is this a new idea that should be considered by all airlines and training facilities?

Perhaps you could pass this procedural good idea on to your airline’s training department and your pilot association’s training committee? By understanding aerodynamics, you can enjoy safe flying. Remember that $afety Pay$.

International Captain Paul Miller

B737 MAX MCAS: Maneuvering Characteristics or Stability Augmentation or Stall Recovery?

Aerodynamics for Naval Aviators was written by Harry Hurt in 1959 and published by the US Navy in 1960. It is still in print and is still in use as an authoritative handbook for pilots to learn the aerodynamics behind the safe operation of aircraft through all areas of the flight envelope. Whether going very fast, or very slow, whether going very high in the sky or flying low to land, the aerodynamic principles explained in this book have helped many aviators fly safely in all manner and variety of aircraft.

On stall recovery in Chapter One, Basic Aerodynamics, Hurt states, “Recovery from stall involves a very simple concept. Since stall is precipitated by an excessive angle of attack, the angle of attack must be decreased. This is a fundamental principle which is common to any airplane.” (See Aerodynamics for Naval Aviators, Ch 1, Effect of High Lift Devices, pg 29).

In my flying experience, there are two ways to reduce the angle of attack (AoA) and a third step in the stall recovery procedure. The first way to reduce AoA is to lower the nose of the aircraft with the elevator towards or even below the horizon. The second way is to add all the power you have and accelerate the aircraft. The third step is to roll wings level. While this does not directly influence the AoA, this step does re-direct the lift force vertical and opposite the weight of the aircraft.

In Chapter Four, Stability and Control, Hurt writes, “The initial tendency to continue in the displacement direction is evidence of static instability and increasing amplitude is proof of dynamic instability.” He writes further, “In most cases, the contribution of the fuselage and the nacelles is destabilizing.” Under the topic of Longitudinal Dynamic Stability, Hurt writes, “dynamic instability will exist when the amplitude of motion increases.”

(See Ch 4,, ibid, Dynamic Stability, pg 245, 256, 279).

According to public media reports of various B737 MAX mishap investigations, the Maneuvering Characteristics Augmentation System or MCAS moves the elevator trim relatively rapidly and to a large displacement angle, in much the same manner that a pilot, hand flying a stall recovery would move the elevator. (See: Interestingly enough however, the MCAS does not engage the auto throttle system to add full power. Not sure why?

So while the concept that the MCAS is improving the longitudinal stability of the B737 MAX, most likely due to engine nacelle longitudinal destabilization factors, this is the engineering argument offered for the MCAS system not being a pilot procedural controlled stability control, such as an elevator, in actuality the MCAS acts very similar to the control inputs of a pilot recovering from a high AoA induced stall, by moving the elevator due to input of a high AoA.

In that regard, it might be a very good idea to:

-first rely on several AoA probe inputs to validate the high AoA data input is in fact a high AoA

-second to display that reading in the cockpit for all to see

– and third let everyone in on what appears to be both a longitudinal stability augmentation system and stall recovery system, so that the owners and operators can maintain it well and operate it safely.

Is the B737MAX Angle of Attack Comparator Systems news story a Distraction from Two Critical Safety Issues?

Is the discussion about the optional equipment of B737MAX angle of attack AoA data comparator systems diverting the discussion from two of the most central safety issues, safety hazard reporting and rapid response, and the full extent of flight crew training?

Why ask that question?
First, the specific hazard of a malfunctioning AoA probe and/or data value input to the flight control system computers, ordering an erroneous massive nose down stab trim control input, was reportedly known to exist on the B737MAX acft before both the Lion Air mishap or the Ethiopian Air mishap.
Who knew and who reported it?
According to reports from pilot groups, 3-5 US based passenger carrier flight crews experienced a similar malfunction and reportedly entered same in the acft maintenance log book, and may have written an airline safety event report as well. Thus at least one or more US certificated airlines may have known of this hazard, meaning that their FAA (principal operating or operations inspector (POI) and their principal maintenance inspector (PMI) either knew or should have known of this hazard, and thus through their Boeing reps, the manufacturer knew or should have known of the hazard. This is to some degree speculation based on reports and the reported procedures for reporting and sharing flight safety hazards between flight crew members, the airlines, the regulators and the manufacturers.

This could mean that FAA and Boeing, if knowing of the hazard,  should have immediately and rapidly issued a safety of flight notice to all B737MAX certificated operators, informing of:
A. the flight hazard
B. the maintenance fix
C. the aircraft operators procedures, either standard, supplemental, non-normal or emergency, as appropriate to respond to this hazard if encountered in operations.

Did FAA or Boeing do this? It is not clear yet how far along this path the FAA and Boeing proceeded. News reports of the Boeing fix underway in January 2019 show that some action was underway prior to the Ethiopian mishap.

Second, and more specifically, a Lion Air flight crew reportedly experienced this hazardous malfunction, on the mishap acft, during the flight previous to the mishap flight. How did Lion Air respond to the reported hazard? Was the hazard reported?  Why did Lion Air maint management and flight ops management assign that acft to fly again, knowing it had experienced the hazardous malfunction on the previous flight? Had that hazard had been resolved? Was the event entered in the aircraft maint discrepancy log book? What possible justification was used to clear the maint discrepancy? Was the airline’s Boeing maint rep asked what to do in this case? Why or why not?

If an additional crew member (ACM), [ACM because he was on the flight deck vs in a passenger seat in the cabin, where he would have been a dead heading crew member DH], a qualified and certificated airman was on the flight deck, assisted the operating crew members by either moving the horizontal stab motor cutoff switches or recommending the same to the operating crew, was that event recorded by Lion Air Flight Safety Manager, investigated and this information promulgated immediately by Lion Air Safety to all Lion Air flight crew members and to their CAA regulators and the manufacturer Boeing? Why or why not?

Why did one flight crew member, the ACM, know how to turn off power to the trim motors with the horizontal trim cutoff switches, and know to turn off the power at that time as a response to the malfunction, but other crew members, and the operating crew members did not?
Boeing B737 Runaway Horizontal Stabilizer Trim Emergency Procedures are published in the Boeing Aircraft Operating Manual or AOM, and Quick Reference Handbook or QRH, and are very similar to the procedures on most or all Boeing passenger acft, such as the B757 and B767. Why did some certified and trained Lion Air crew members know that and others seemed to not know that? Why did the Ethiopian Air flight crew apparently not know that? How is that possible?

Would have having an AoA comparator and disagreement warning system have made a difference if the system did not automatically disengage the horizontal stab automatic trim system known now reportedly as the MCAS Maneuvering Control Augmentation System? If the flight crew was not trained on MCAS, how would a comparator system have helped them? Even without a comparator, merely knowing to flip the horizontal stab trim cutoff switches at the first instance of uncommanded horizontal stab trim movement, should have resolved the runaway stab trim issue enough to allow the flight crew to land the aircraft, in our opinion.

So, in our opinion, these mishaps reveal two massively glaring safety of flight issues:
First, why are known and reported equipment hazards and procedural short falls not resolved quickly, rapidly and universally by the airline, their CAA, EASA or FAA regulators and the equipment manufacturers such as Boeing or Airbus?  Why does the hazard reporting system seem to work most of the time but not all of the time? Is there a regulator difference in hazard reporting system and resolution? If so, why?
Second, why are some flight crew members trained, qualified and certified to operate with only a bare minimum FAA type rating training at some airlines in the global commercial scheduled airline community, and then little or nothing else further, while flight crew members at the three major US based airlines are given four to five times more training subject-wise, twice as deep training hands-on sim-wise, trained to competence and then regularly receive repetitive in the cockpit line oriented safety audits, line checks with immediate feedback, Advanced Qualification Program or AQP reviews, plus take home systems and procedural tests, exposures to safety forums, monthly or weekly ASAP Event Review Team reports and FOQA training reports?
Why is there such an enormous difference in flight crew procedural training?
Do you think that flight crew training and flight safety are closely related and perhaps that is an unaddressed global or international commercial scheduled airline safety issue?

In the opinion of SafetyForecast, two issues may be being ignored here, two issues which are literally the foundation elements for mishap -free commercial scheduled airline flight operations: [Yes we believe that mishap free commercial scheduled flight operations can be achieved by constantly reporting and resolving flight safety hazards and by training flight crew members on all procedures, equipment , limitations available and repeating and refreshing that training regularly.]

First, where is the flight hazard reporting and resolution safety program in non-US based airlines? Does it exist and how robust is it? Does it seek to both report safety of flight hazards and rapidly resolve these hazards? “All safety is local.” Citation: Paul Miller, Better Safe Inc.

Where is the hazard reporting and resolution interface joint safety program between the manufacturer, regulator, certificated commercial scheduled airline and the certified flight crwe member?

Remembering that “All Safety Is Joint”, (Citation Paul Miller, Better Safe Inc.) meaning that safety is really a joint effort between the certificated airmen, the certificated airline, the CAA regulator and the equipment manufacturer.

Second, where is the highly developed, broad based and in depth flight crew procedural based training program, above and way beyond type training,  globally, in many non-US based airlines? Why are some operating flight crew certified in type and then given little if any additional training?
“If you seek one level of safety in commercial airline operations, should you seek one level of training?” (Citation: Paul Miller and David Williams, SafetyForecast, Better Safe Inc and Safety Net Inc.)

There is a much bigger flight safety story here, in our opinion and it involves both safety hazard and resolution programs and flight crew training programs.

Paul Miller, int’l B757/767 captain, retired, 43 years of line and instructional flying
David Williams, US FAA designated airline check airman and airline captain, retired

B737 MAX: Issues of Boeing and the FAA

In my opinion, the issue is not that the flight crew received “aircraft differences training” (systems, limits and operating procedures differences between the B737-800 and B737-900, and the B737 MAX) on an iPad. Don’t shoot the messenger. The use of an iPad as a syllabus media is not invalid and may be likened to reading a book on a computer tablet.

From the point of safety management, the real first issue is that the Maneuver Control Augmentation System (MCAS) may not have been included in the aircraft differences training syllabus. The differences training syllabus may have been created by Boeing as an FAA certification requirement. The MCAS had been engineered, tested, installed and delivered on the new B737 MAX by Boeing, as a flight control system on the B737 MAX, a system different from the flight controls on B737 -800 and -900.

The second issue is that the FAA signed off on both the B737 MAX aircraft as certified safe for flight and signed off on Boeing’s B737 MAX “aircraft differneces training syllabus” as sufficient for flight crew training for passenger airline flight crew members certified to operate the B737-800 and B737-900 passenger aircraft.

The third issue is that neither Boeing nor the FAA informed passenger carrier airlines about this different, new and additional B737 MAX flight control system.

The fourth issue is that, after airline pilots reportedly submitted flight hazard incidents of apparent uncommanded pitch trim movements to their airlines, and the airlines reported these flight hazard incidents to Boeing and the FAA, that neither the manufacturer Boeing nor the regulator the FAA apparently took any actions to resolve the flight hazard or inform other airlines of the occurrence of the reported flight hazards.. This allowed a known flight hazard to exist unresolved amongst airline operators of the B737 MAX, which then apparently and eventually resulted in two fatal passenger airline disaster mishaps, when the hazard reoccurred.

As with many airline disasters, both the hazard and the failure to rapidly respond to the known and reported hazard has resulted in what could be considered two totally preventable fatal mishap disasters.

Effective commercial flight safety programs of Safety Forecasts and Plans should not only have both the ability to detect and report flight hazards, but also have the ability to rapidly respond with an immediate hazard procedural response, an interim hazard policy remediation and a long term hazard resolution.

Contact SafetyForecast Director of Safety Policy Captain Paul Miller today for further consult and assistance. Our goal is to save your operation from fatal mishaps, costly material losses and the diversion of time, talent and resources away from the main goals of safe and profitable flight operations.

Lining Up to Land on a Taxiway?

In low visibility, at night, as the sun dawns and as the sunsets, flight crew members mistaking ramps, taxiways, parking lots and other places for the approach to the landing runway, can pose an unexpected challenge to commercial flights.
One cloudy and shadowy late afternoon, I sat as PM with a great international captain as PF, who momentarily become mis-directed by several flashing yellow lights on ground support vehicles. Just at this moment of time, while the PF was transitioning his/her gaze from inside to outside, these three lights were lined up perfectly in a slight right arc. This arc just happened to be  very similar to the white right arcing lead in-lights to an old and famous Pac-rim coastal airport and a distraction occurred at the end of a 10 1/2 hour flight and a 12 hour duty day.

As the pilot-monitoring, I’d fortunately procedurally had the chance to be looking outside long enough to have already picked up the actual runway. The runway  was another 45 degrees to the right, in our right banked 90 degree turn to final. I saw the captains eys lock onto the point of the three flashing yellow lights and noted his/her confusion that there was no runway to be seen.

Without a word, I tapped him/her on the shoulder and pointed to the right. The captain quickly corrected and moments later, we completed an uneventful 10 1/2 hour flight, in the shadows of a summer sunset, with a smooth touchdown.

On another flight, while looking directly into the rising sun, the morning mist became almost impenetrable. So when the pilot flying lined up on the bold black asphalt taxiway, out of a right 180 approach circling turn and not the concrete runway, which, by lack of contrast with the surrounding runway environment, had literally become camouflaged by the mist, I was not surprised. “Go around,” seemed wise, as we were both fatigued. A salvage at that point would have been possible, I suppose, but unwise, so “Go around,” is what I said. The second approach and the landing by this great first officer PF was perfect. The explanation to tower was that we’d lost visual on the runway in the sun.

On another occasion, while breaking out of a stormy night overcast at the end of a seven hour international flight, the first few white lights we saw, just happened to be lined up in a row and had red flashing lights atop. This image looked like something near or around an airport, but in a moment I realized it wasn’t the runway environment at all. The lights those of a nearby athletic stadium parking lot.

Just a moments distraction can be very difficult to recover from when things are happening fast. Fortunately for us, in another moment we had the real runway environment in sight and we landed safely.

So how can a pilot avoid landing on the wrong runway during 43 years of flying?
I would champion communications. Yes, simply good and ongoing and free-from-restrictions communications between the PF and the PM.

1. Brief what to expect during the approach brief: various lights, configurations, markings and signage around the runway environment.
2. Always, always, always tune up the ILS, just to have good glide slope and the localizer support. This is free and invaluable. Never bypass this step.
3. Double check and brief magnetic headings. Many runway configurations at large aerodromes can be confusing especially if you are doing a circling approach.
4. Keep talking during the approach with the flight crew, give everyone a chance to say what they are thinking. You’ll be surprised what golden nuggets can save your bacon.
5. Use the electronic magic, but only as a tool, not as a crutch. Plan also wha to do in the event that you loose all electrics. Know what to do. It’ll save you once or twice in 40 years of flying.
6. Most of all remember to communicate with your crew, with ATC and your inner gut feelings. When everything is lined up right, you will know. If you are at all confused, say something, ask the PM or ask tower if you are lined up correct. It costs nothing to ask.
7. Trust your instruments, not because they are electronic, but because you’ve set them up right, you’ve cross checked them, you’ve gotten a good audio morse-code ID check, and the maps, both paper and electronic, all line up with what you are seeing outside.
8. Lastly, if you see something out of place, say something! You might be the only member of the crew, who at that point in time, has the correct picture, ensuring your flight does not line up to land on a taxiway.

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UAE 521, 3 August 16 at Dubai Int’l

100_3971Looking at the last few entries of the  flight aware track log for UAE 521, showing significant wind shear is of interest. The Dubai  Int’l weather reported in the Metar is also of interest.

Metar     OMDB 030900Z 11021KT 3000 BLDU NSC 49/07 Q0993 WS ALL RWY TEMPO 35015KT 1500

[Translated: wind from 110 degrees at 21 knots (observed a few feet above the ground), visibility 3000 meters with blowing dust, with no significant changes in the last reporting period, temperature of 49 degrees Celsius, dew point at 9 degrees Celsius,  lower than standard atmospheric pressure of 993, with wind shear observed and or reported on all runways, the a temporary wind out of 350 degrees at 15 knots with 1500 meters visibility.]

Some news reports say the gear problem occurred prior to landing. But if that is so, why didn’t the crew stay airborne, attempt to get the gear down green and then land?? If the right main was problematic, such as hung up or unsafe down, as reported, why wasn’t an airborne emergency declared by the crew, with the crew requesting tower to have fire crews standing by for an unsafe gear landing?? One report indicates that the gear had been raised because the crew was performing a Go-Around, but that doesn’t account for procedures that state in essence: Add Go-Around Thrust, set flaps to approach, Establish a positive rate of climb, then raise the gear. [Go Around Thrust, Flaps 20, Positive Rate, Gear UP are the memory items for a Boeing Go Around.]

So if they were not executing a Go Around Procedure, which I suspect that they were not, if the crew raised the gear,  in lieu of a gear collapse occurring, why had they not added the power to actually go around??  This could account for the landing without three gear down and locked. However, the left main and nose gear appear to be down and locked, so I would doubt that the gear was raised manually for a go around, because if they had raised the handle to raise the gear,  all of  the gear would have been unlocked and thus collapsed on touch down, which they were not.

If, as I suspect, the gear was down and locked with three green, I would then look to the Metar and flight aware flight log ( see above link) for clues.

Possibly the thrust levers were in auto-throttle mode and had moved back towards idle due to over performance head wind shear. The established rate of descent last recorded on the Flight Aware Log was at -800 fpm, but the airspeed had accelerated towards 180 knots.

So, without the crew clicking the auto pilot and auto thrust levers off, in order to hand fly the flight controls and the thrust levers, or at least, hand fly the power by the adjusting  the  thrust levers, and leaving the auto flight controls coupled to the flight director and ILS, the final descent onto the runway could have been close to -800 fpm. It could have  even been higher if a lower power induced higher sink rate had developed, as I suspect it had.  With a previously steady -800 fpm descent rate, high IAS above bug, the power would have been back, setting up an eventual higher sink rate in a few seconds. To keep the aircraft on glide slope, the auto pilot would start raising the nose attitude, until at or above the L/D max point on the lift curve, the drag increased so much that the aircraft speed slowed. This would lead to a higher sink rate.

Possibly the sink rate at the time was in excess of the radar altimeter cued auto pilot flare capability, with the possibility of a previous increased IAS and thus higher descent rate, as the IAS bled off as the power remained low. This could have resulted in a pretty hard landing, along with what looked like a slight left crab, adding stress to the gear, all of which could have collapsed the right main gear.

Additionally, upon the high descent rate touch down, the whip action of the wing and engine pod, could have led to an attachment point-pin failure, due to whip action aka “over-momenting” in engineering terms, resulting in the engine pod separation, with a subsequent fuel leak and fire.

This analysis is all totally speculation though at this time.100_3978

Just Culture Arguments

IMG_6033Advocating for a Just Culture, without referencing the logic of a larger safety, legal and administrative contextual framework can take on the appearance of advocating for an exemption to all the laws of all the nations that have developed over all time with respect to one party doing harm to another party.

For example, let’s consider the Air France 447 case. For which party in this mishap should a Just Culture exemption to all law on harm be advocated?

Consider the pitot equipment manufacturer, the air frame builder, the air line certificate holder and the certificate holder CAA regulator government.
Did or did not all four of these parties know, and fully know, ahead of time , ahead of the time of operation of AF447, of the pitot equipment’s failure to perform on previous occasions? Were these four parties or were these parties not completely familiar with the certain likelihood that flight operations in the inter tropical convergence zone involved instrument meteorological conditions in icing at cruising flight levels? Were not these four parties, less the pitot manufacturer, completely familiar with flight operational standard procedures and training of the flight crew?

Nevertheless, did not the certificate holder, with the approval of various CAA regulators, propose to operate and receive approval for an operation into an area of known and well known hazardous weather, all the while with known defective equipment?

See, there is one strange part of the whole Just Culture argument that needs to be looked at very much more closer than, in my opinion, it has been looked at before. Think about this:
Under all the laws of all the nations, are the flight crew considered separate parties, separate certificate holders, separate parties from the airline certificate holders all the time, or at least during the time that they are operating?

Or are they considered agents of the operating, certificate-holding airline?

If they are legally considered agents of the operating certificate-holding airline, how would any flight crew legal exemption from liability for harm done during an operation, the Just Culture argument,  have a follow-on exemption from liability for the airline certificate holder?

Is this not a grey area, a not well defined legal area, an area where an argument for Just Culture for airline flight crews begins to grow dialectic from all other laws governing agents of companies, for example the captain of a ship in admiralty law, the CEO of a corporation under corporate law and similar company-agent relationship laws that exist all over the world? Is this a very large and complicated problem that Just Culture has addressed to the satisfaction of at least some of the countries of the world? In my opinion, even the countries in ICAO, have not fully considered that there really are many more layers to this issue as it relates to global commercial aviation safety mishap investigations.
In the case of AF447, the flight crew training by all appearances and by any analysis that has been published, was, in my opinion, not adequate for the known hazards to be faced and subsequently for the hazards actually faced by the flight crew of AF447,  again in my opinion.
But, in IFALPA’s opinion and policy view, is or is not flight crew training the responsibility of the airline certificate holder and under direct supervision of the CAA regulator? So, where does the Just Culture argument take us in terms of crew training, as far as who is responsible for a crew that, as I stated in my opinion, was not adequately trained?  Is training, such an absolute essential part and basis of safe commercial flight operations, intrinsically tied to the airline, the CAA regulator and the equipment manufacturer? If this is so, how can the crew’s position be lifted out of the events of a commercial aviation mishap?

Or maybe is that just what the Just Culture advocates are saying, that the crew was trained according to the standards of parties other than themselves?  But doesn’t that appear to create a huge legal problem for any party harmed by a commercial flight operation? If the Just Culture argument contends that the crew is not an agent of the company and thus should not be held, as agents, individually culpable, then who should be? If the non-operating and potentially non-flight certified corporate officers are to be held culpable for harm caused by a commercial operation, what is the relationship accountability between the crew and the corporate officers?  This can devolve into an extremely complex set of arguments, in my opinion.

May arguments of exemptions from laws addressing harm have a severe uphill challenge, when the argument is solidly based on a footing that training costs are minimized by airlines solely for economic arguments? The challenge grows even more severely uphill, when and if crew training documentation has a large gap in the area of operations in known and well known hazards of severe weather with defective equipment, weak supervision communications links and poor enroute supervisory oversight, as was the case of AF447, in my opinion. The training gap itself raises the classic liability negligence questions of who knew about the hazards, equipment limitations and weather and when did they know it?
If IFALPA’s Just Culture policy is aimed at thawing the safety channel into insight of human error (also known as human factors), now very often frozen solid by centuries old laws addressing harm, liabilities and negligence, then the Just Culture policy should very clearly state so.
If however, IFALPA’s Just Culture directly or indirectly attempts or even appears to attempt, to advocate an exemption by any party to harm, including flight crew, from all the laws of all the countries, this advocacy is more likely to look like a dodge from responsibility,  than a safety policy to quickly get to the bottom of the cause of a mishap, in my opinion, and thus not likely to enjoy widespread acceptance.
In the US Supreme Court case of Weber vs US Government, the nine justices clearly differentiated the separate safety function of the mishap investigation team from the parallel legal liability functions of lawyers representing various harmed parties and the third parallel regulatory administrative function occurring simultaneously as the result of an aircraft mishap.

100_4230Since all ICAO commercial aircraft mishaps are investigated by state agencies, I find the arguments for a differentiated government safety investigation, asking solely the questions, “How did this mishap occur?” and “How can we prevent this mishap from recurring?” are clearly warranted. In their rare unanimous 9-0 Supreme Court decision, upholding the arguments for keeping thawed the channels of investigation of human factors associated with aircraft mishaps and direct testimony of persons with first hand knowledge, the court at no time granted, suggested nor established any prohibition to any party for exemption to liability for harm or any independent investigation to determine the legal purpose questions of “Who was harmed?” and “Who Pays?”
Instead the court prevented lawyers seeking legal liability claims evidence from having access to safety investigation evidence, and in particular, personal testimony given on the promise of confidentiality, and solely for the Safety Purpose, in order to quickly fix the safety hazard, thereby preventing further harm in a subsequent flight operation.
At no time, however,  did the court prevent any harmed party from conducting their own separate legal liability investigation to determine who was harmed and who should pay for the damages.

There was absolutely every reason for lawyers representing Weber for conducting their own investigation. However, they saw the safety investigation as the only one possible, erroneously so in my opinion. In my opinion this was a mistake. Instead of Weber seeking an exemption to have access to the safety investigation, they should have gotten busy conducting their own investigation to ask, “Who was at fault for the damages and who should pay?” They should have interviewed their own witnesses, found their own evidence and determined their own facts through testimony they collected. Instead, they made a raid on the Safety Purpose investigation and were soundly rebuffed and rightfully so, by the unanimous decision of the US Supreme Court.
Nor, do I believe, should Just Culture arguments seek such exemptions from liability damage claims and from administrative regulatory laws related to flight crew certification.
The questions “Who was harmed?” and “Who is going to pay for the damages?” are rightful and powerful questions that will long remain part of the laws that define the operational limits of any commercial company. Additionally, the question of certification continuance, suspension, revocation or further training should be expected and rightfully so in the event of a commercial airline mishap.
I believe it is The Safety Purpose, or what Europeans label as Just Culture on the other hand, to separately advocate for mishap prevention, all the while giving the crew and any other related party, the opportunity to provide safety testimony into the human factors related to commercial flight operations. Safety and Safety alone should ask, “How did this happen and how do we keep this from happening again?” If we safety advocates stick with these questions, the Safety Purpose, then our efforts, the efforts to achieve a Just Culture for example in Europe and other parts of the world, will succeed, in my opinion.

At the same time, we must look at the laws governing agents of companies and determine whether moving forward, how do commercial flight crew members currently fit into the framework of centuries old shipping company agent laws.101_0241

Making 2016 a Successful Year for Your Commercial Aviation Organization

Making 2016 a successful year for your commercial aviation organization depends on one word:  training. By emphasizing flight crew training, a commercial company equips their operating crew members with the tools to conduct flight operations smoothly and to confront any unexpected challenges successfully.  When fiscal year 2016 comes to an end, success could be measured by two matrices many organizations have in common.

First, you know that you have had a successful year if injuries to people are at a minimum. We are talking flight crews, ground crews, maintenance crews, passenger customers and all others with whom your company interacts. Deaths of course cast an irrevocable shadow over your operation. Training has been found in most if not all mishap investigations to have been lacking when injuries and death occur. Training is procedural based, so when people are involved in violation of procedures that lead to mishaps, somehow training failed to achieve a level of safe performance. Who needs a mishap investigation to tell us that? Hopefully no one. Instead of investing time in injury investigations, invest time in training, so that people are doing the job per procedures. The costs involved with injuries and death are monumental, beyond the imagination. Worse yet, after these costs have been paid, the injury and death remains, a haunting reminder of training failure.

Second to account for is damage and destruction of property, equipment, material assets, things that cost money. Nothing cuts into profits than replacing damaged and destroyed property. Worse yet is all the paperwork associated with the loss investigations. But in these investigations, it is very common to discover that people somehow did not know what they were doing when they damaged or destroyed the equipment. Why is that? Was training lacking or only minimally provided? Did the training have it’s origin in the company’s procedures? Want to enjoy a successful 2016? Make sure all people know what they are doing with the equipment that they use to do the job. If they are flight crew, do they know every switch, every light, every function of every system? Have they flown every procedure in the procedures manual in the simulator? Have they practiced the Go Around in the sim enough to do it well every time, smoothly every time, coordinated every time with their fellow crew member?

Training is training only when it is based on procedures. That is the definition of training: practicing the written standardized procedures associated with the company certification.  Think about that. Who knows the company’s certification operating specifications? Does everyone know them?  Are all pilots educated on the subject of operations specifications? Does everyone know that the SOP is based on these Ops Specs? Does every one know that training is based on the procedures? If not, seems like it would be worthwhile to connect these dots for all employees and managers.

By training all of the people in your organization to comply with the procedures that support the ops specs, your company could have a very successful 2016.

How Unusuality and Reality Intersect in Flight Safety: A Simple Metric for Determining Major Hazards to Commercial Flight Operations from the Unremarkable Accumulation of Minor Unfavorable Elements and a Recommended Operations Adjustment Procedure to Avoid Mishap Occurrence

poster safety forecast-3imageAbstract: The cascading collection of seemingly minor unfavorable elements during a particular commercial flight can often arouse little notice because there may be no collective safety measuring system or metric to assemble disparate elements. However, just as the story of “the straw that breaks the camel’s back[1]” informs us, flight crew members facing unusual accumulations of circumstances during flight operations from aircraft automation systems, the weather, airfield navigation equipment, human factors,  their passengers and payloads, and at times even local and international politics can at times be overwhelmed. Without a metric to determine how far from normal reality a particular flight has deviated, the flight crew, the dispatchers, air traffic control and supervisory personnel in regulatory positions and corporate administration may not have an effective tool to detrrmine when, where and how to establish additional procedures and limitations to address any level of  significant deviations from normal reality or as we have label this, the rise of Unusuality.

Captain David Williams and his writing partner Captain Paul Miller have developed a simple measuring tool, a comprehensive system and an easy to use metric to aid flight crew members, dispatchers and others involved in commercial flight operations to determine when the accumulation of seemingly unrelated elements begins to form a major hazard to safety. The metric is in the form of a checklist and addresses the flight crew, the aircraft, the natural environment and the automated flight environment. It provides guidance when to consider alternative procedures from an aggregate of unusual elements labeled “Unusuality.” When the deviation from normality is contrasted with the normal reality, or normality, the metric become a clear tool comprehensible by the layman and professional alike, this being an important tool for communications, to bring everyone onboard quickly. Why? Every airline and every situation of combined factors will be different and particular. That is why these combinations often are not noticed until after the mishap investigation begins, if in fact a mishap has occurred, as the safety record shows it often has.

The take away from this paper will be a detailed checklist to allow all involved in commercial flight operations to identify hazards of Unusuality, and take action to prevent a costly mishap.image


Question: Can we use what we already know to prevent commercial aviation mishaps?

National Transportation Safety Board member Robert Sumwalt recently stated “We want to get the facts before we start making judgments.”[2] He also stated that the NTSB looks at three major areas during a mishap investigation: the environment, the people and the machine.[3]

If the facts were in existence prior to a mishap, that is, that they were able to be discovered by the NTSB as facts, after the mishap and provide the NTSB with the factual cause(s) of the mishap, could these same facts, be knowable at the time of the mishap? Furthermore, since aviation mishaps are very fluid and seem to have a very fast moving time line of factual events[4], could the facts that were later determined to have been the cause(s) of the mishap, be known, both as they were occurring and, if in existence prior to a mishap, be known and recognizable prior to the mishap?100_2925

If the facts that cause a mishap can be known and recognized prior to the mishap, can we create a method, a metric of recognizing these facts as things-about-to-become-causes[5] for the mishap, prior to the mishap?

If the methodology that the NTSB uses to determine these causes after the mishap, is valid and continues to be validated by each mishap investigation, could we not adapt this methodology into some form of recognition procedure, a metric to identify these causes, as they factually exist, prior to the mishap? If we can adapt this methodology to create a procedure to recognize these facts as things-about-to-become-causes could we create a metric, that each airline could adapt, to serve as their own local mishap prevention flight safety management procedure tool, since each airline would and should know their own environment, people and equipment the best?[6]

If the various “things-about-to-become-causes” were relabeled to be “Negative Stressors”[7] could they be given a vector value, that is both a size value and a direction value, in a manner similar to false color imaging used by radio astronomical observers?[8]100_4153

If we could give these Negative Stressors vector values, could we quantitatively sum these vectors with other similarly derived vector values for such things as crew ability and normal operational demands and then plot them graphically?

If by plotting graphically the negative stressors along with normal operational demands and crew abilities, could we get a graphical understanding of rare circumstances where the vectors of negative stressors exceeds the crew ability and the normal operational demand curves? If we could get a graphical understanding of such areas of exceedance, could we relabel these areas as Unusuality, that is, areas on the graph where the collective level of negative stressor vectors far exceeds any level of expectation of normal operational demand, or normalcy for that aircrew?100_3978

If we can calculate and plot Unusuality by referencing the facts after a mishap, facts that were all known and in existence before the mishap, could we calculate and plot Unusuality prior to a mishap?

 If we could calculate and plot Unusuality prior to a mishap, could any airline then use this recognition of Unusuality to adjust that airline’s standard operating procedures as a method of intervening ahead of time to prevent a mishap from occurring in the first place?

Could commercial airline mishaps be prevented by better understanding, recognizing and acting locally on occurrences of Unusuality?

 As the various operational elements and flight crew dynamics combine and integrate during a flight’s duration, the cumulative effects can create significant hazard to the operational safety of that flight. By analyzing aircraft After Accident Reports (AAR) from various governmental organizations and identifying both the subjective and qualitative elements gleaned from the contemporary AAR’s data base, a demonstrated pattern of operational detriments can be determined as stressors against crew capability and thereby addressed and mitigated. With current flight crew training and checking programs, agency regulatory oversight and redundant aircraft systems, rarely does a single negative element encountered during a flight create an anomaly of sufficient proportion that it will result in an accident. Conversely, when several negative elements or stressors exist, are experienced or are encountered, the effects can be cumulative and translate into a cumulative flight hazard, that may exceed the individual threat of each negative stressor and exceed the crews’ ability to cope with, handle or to otherwise, using trained standard operating procedures, successfully complete the flight. As positive elements can interact and combine to create a positive synergy[9] with an improved and safer operating environment, the converse effect of negative elements, we postulate, could create a negative synergy[10] and is of an equal but negative dynamic. The cumulative negative stressors could overwhelm a flight crew, rendering them ineffective and unable to extricate themselves from the dangerous and deteriorating situation in a timely manner.100_2920

While the effect of each negative stressor may be considered of limited significance, the combined effects of such multiple elements becomes apparent in retrospect, as noted in After Accident Reports[11]. If flight crews and oversight agencies can recognize the compounding negative synergy of such stressors ahead of time by some form of a observatory measuring metric, an emerging threat can be recognized, anticipated, mitigated or avoided. The area that we are studying is the difference between a particular crews’ ability to handle hazards, unexpected events and failures and the level of accumulation of these hazards, unexpected events and failures. Thus, as a particular airline training and procedures program rises to be more comprehensive, the difference could be reduced. As the involvement of more of the management team, such as dispatch, meteorology, scheduling, maintenance and chief pilot’s office, increases, the difference could, once again decrease. As a crew is more mentally sharp due to rest[12] and diminishment of factors of mental distraction, their capability could increase substantially and thus the difference would be reduced. We define the difference between the accumulated level of negative stressors and the current crews ability to cope successfully with them in total, as the level of Unusuality. Again, it is not any single factor that we are addressing, but rather the difference between the sum total negative stressors and the sum total ability of that crew at that time to cope with all of them in a timely and successful manner. Unusuality may be important to understand since very often post accident reviews by boards and later airline procedure writers and training program writers may focus on one causal element at a time. For example, the ATSB (investigating mishap board) cited the crew’s delay to dump fuel to landing weight as a itemized factor, leading the reader to believe that if they only had not delayed their approach to landing , that this mishap might have been averted. But the crew of Swiss Air 111 was dealing simultaneously with an overwhelming number of factors, all at the same time. They were not startled, they were overwhelmed. They were dealing with night, over the water, severe and unknown electrical malfunction that was rapidly escalating, a design and engineering flaw within the aircraft’s post production modification, for which documentation and trained non-normal procedures were ineffective, and a heavy aircraft, soon after take off, fueled for a transatlantic crossing, at much heavier than normal landing weight. The crew was well trained and qualified; however, the sum total of negative stressors appears to have overwhelmed the crew’s ability to react timely and successfully. [13] The level of Unusuality was so great in this case that it prevented a successful outcome. Yet, the design and engineering flaw was detectible by mishap investigators after the mangled wreckage was lifted from the ocean floor months after the mishap. Could not a quality assurance inspection have discovered the same flaw prior to the mishap? Could the crew have dived as rapidly as possible to the end of a runway at nearby Nova Scotia, landed heavy and omitted the attempt at fuel dumping to standard landing weight? Comments invoking this procedure were made afterwards[14]. Could not similar conclusions have been reached by local procedures writers at the airline, the manufacturer or the regulator prior to a mishap occurring? We believe that there is something to be learned.101_0559

To support this hypothesis, the authors have reviewed data related to negative elements from multiple National Transportation Safety Board (NTSB) Aircraft Accident Reports (AAR) and ICAO AAR from 1990-2013 for documented accident research, both in the USA and Europe. These negative stressors are then evaluated for a numerical cumulative causal relationship. If these negative elements are cumulative, we postulate that there may exist more than just an anecdotal relationship.

This paper postulates that the safety of individual flights can be improved if flight crew members and the assigned flight dispatcher are knowledgeable of these negative stressor elements and the potential negative cumulative effect. They then can take locally generated procedural actions and other timely and appropriate timely mitigation measures to either eliminate or reduce those elements and prevent a mishap from occurring.

We postulate that if cumulative negative effects can contribute to an accident, then the corollary exists for the cumulative “positive element” synergy to exist that contributes to an improved safety effectiveness by the flight crew. Possible examples of this postulated “positive element synergy” might be an explanation for several remarkable accidents where flight crew interactions contributed to a more successful outcome than might have been expected. Two examples might be further evaluated for such positive synergistic effect; United Airlines Flight 232 Sioux Falls SD, July 1989 and USAir Flight 1549, January 15, 2009, the successful Airbus A320 ditching, the “Miracle on the Hudson”.

End of Introduction.



“The best-laid plans of mice and men / Often go awry”   from To a Mouse, by Robert Burns[15]


Board Determined Causal Factors:    The accidents investigated by the National Transportation Safety Board (NTSB) list the Probable Cause and Contributing causal factors.[16] Many of these principle Probable Cause factors have been cited in multiple accidents.[17] Significant efforts have been enacted by all major stakeholders in the aviation, safety industry and regulatory agencies to correct these causal factors with improved training, better equipment, and governing regulations.[18] Efforts to identify and correct potential causes of future accidents have met mixed results although the overall accident rate has significantly decreased during these past five decades.[19] Repetitive accidents with the same Probable Cause, however continue to occur. Today, the chances of being in a commercial airline accident are statistically very low, one in a million or less[20]. However, we have found that several major elements exhibit a recurring frequency and are particularly problematic despite significant and continual efforts to correct, mitigate and prevent such occurrences. Major programs and technical advances such as improved flight crew training standards, onboard flight weather radar, Traffic Collision Avoidance System (TCAS II/III), Enhanced Ground Proximity Warning System (EGPWS), improved navigation equipment, airport taxiway and runway markings and lighting have directly aided flight safety. Despite aircraft design improvements, industry, regulatory, employee efforts, improved flight crew training and advanced avionics, multiple causal factors, what we call negative stressors, continue to negatively impact safe operations. While these negative stressors are known, programs to mitigate these mishap causal elements, is not the total solution.101_0245

We define Unusuality as the difference between accumulated negative stressors and the crew’s ability to counter the cumulative effects of those negative stressors at any point in time. Other mishap prevention programs have met with mixed effectiveness, because they are often compared against an ideal, well rested crew, where most often, negative stressors are presented one at a time in typical FAR Part 121 training. [21]

But our study of multiple mishap board AARs has determined that virtually all mishaps result after an unusually high level and near-simultaneous or cascading presentation of negative stressors. In most cases, mishap board AARs did not list one singular negative stressor as the Probable and/or Contributing Cause. In stark contrast rather, virtually every mishap board listed an accumulative set of Probable and Contributing Causes. It is our argument that crews were in many, if not most cases overwhelmed by this accumulation of the negative stressors of all of Probable and Contributing Causes happening at that time, above and beyond their ability to react, cope and handle the accumulated causes. This overwhelming level of causes, as listed by the mishap investigation boards, that exceeds the crews’ ability is what we define as Unusuality. It is important to understand that Unusuality is not merely the accumulation of negative stressors as listed by mishap investigation boards as Probable and Contributing Causes. Rather, Unusuality is the difference between the overwhelming accumulation negative stressors and the crews’ ability to react successfully at that time. Part of the common confusion with this calculation is that not every crew performs at the same level. Due to teamwork, familiarity, a more developed skill set, a wider aeronautical education and training back ground, some people appear to be able to handle just about anything thrown at them. While they may use written SOP, the also may dip deep into a well of additional knowledge brought to work from off campus studies and training, personal ability and mental acuity possessed by few. The crew of United 232 that landed an DC-10 with no hydraulic power to operate flight controls used essentially their cooperative wits in place of SOP to bring the aircraft to the runway, saving 185 lives of the 296 persons onboard. [22]


If the Probable Cause is easily identified after the accident by investigative methods, why cannot methods be employed to identify Probable Causes before the accident occurs?

What is Unusuality as it applies to flight crews and the stressors that contribute to an aircraft accident? While the Probable Cause of an accident may be readily apparent, what other elements contributed to that accident and led that trained flight crew to a critical operational failure? Probable Causes and Contributing Causes leading to an accident we define as negative stressors. These negative stressors   have a cumulative effect, not a singular effect. The cumulative effect of the negative stressors, and not just the causes considered singularly, that overwhelm the crew ability, may be the issue that needs to be understood.   Again we define Unusuality as the difference between a particular crew’s ability to perform on a particular flight while influenced by the sum total of negative stressors encountered.

While it is beyond the scope of this paper to sufficiently quantify the stressors as they relate to Unusuality, it is an objective of the authors to have companies review and develop methods with their stakeholders (companies, pilot groups, safety officials, regulators, policy writers) to assess the stressors that impact their organization’s operations and to establish a working group to study the associated dynamics. When those specific stressors are identified and considered, a company specific metric can be designed and evaluated. While organizations may have similar stressors, one company may have reach the point of “Unusuality (cumulative stressors minus crew’s abilities at that time) while another company doing similar operations may NOT reach “Unusuality”. Different flight crews within the same company, because of individual abilities, use of SOP’s, refined CRM skills and previous training may NOT reach the point of “Unusuality”. Why do some crew members have higher skill levels than others? All crew members are required to pass the same check rides,

Consider USAir Flight 1549, the “Miracle on the Hudson” (bird strikes causing loss of both engines causing the subsequent ditching in the Hudson River[23]). Although most flight crews are hazarded by bird strikes, this aircraft’s flight crew effectively managed a double engine failure while at 2818 feet agl, performing multiple emergency QRH 2-crew “response, “confirm”, comply” procedures, multiple coordinated relight attempts, notifying the passengers to “brace for impact”, and configuring the aircraft for a successful dead-stick ditched landing, remarkably all within 3 minutes and 33 seconds.[24] For this crew to achieve this level of effective CRM and airmanship when confronted with multiple challenging stressors, yet not reach the point of “Unusuality” is most significant even to consider. Would other flight crews within that same company or any other airline, given the same circumstances, have been able to achieve this same level of performance?100_2930

What we are saying is that crew ability varies because of many factors. Some of these factors may be level of training as noted in our paper Training to Safety in Commercial Airline Operations. [25]

“Unusuality” metric is different for each operator. An airline operating under FAR part 121 with aircraft equipped with infrared runway detection heads up devices installed in the flight deck may be certified to operate down to a RVR of 600, while most similar carriers without that equipment may be limited to 1200 RVR.

Some airlines are so equipped and flight crews trained to permit full CAT IIIC operations with an RVR of 500. Sufficient equipping, maintenance and flight crew training is required for authorizing certification. The point of a concerning level of Unusualty where crew’s abilities to operate do not meet required operations levels would be different for each of these two air carriers although the stressors may be alike.101_0228

The Unusualty metric should prompt added attention by stake holders. Mitigation to provide for a safer operating margin would be postulated by those involved. Mitigations might include:

  1. Increased flight crew training in a specific recurring problematic stressor, such as fatigue (recognizing fatigue factors; possible flight schedules modifications; developing an improved company policy for calling in because of fatigue; increasing crew manning numbers; replacing a current crew with a reserve crew for the last flight of the sequence when marginal destination weather or airfield stressors exist (precision approach out of service, tailwind landing, icing conditions, severe weather en route or at airport, etc.).
  2. Specific flight and duty day limitations for captains when performing Initial Operating Experience (IOE).
  3. Replacing a low time flight crew member with a more experienced member for a demanding approach or a particularly demanding airport.

NASA Ames Research Center Counter Measures Fatigue Studies[26] (footnote) evaluated flight crew performance and documented degradations from the optimum effectiveness even for experienced and well trained flight crews. Fatigue, a frequently present stressor directly degrades crew coordination, communications skills, procedural accuracy, alternatives planning, and visual perceptions.   Because fatigue becomes consuming in the later stage of a crew’s duty time, the added demands placed on a flight crew, while not being necessarily obvious to the crew, becomes apparent in the post accident review. In this instance as the effects of fatigue accumulate, the level of Unusuality (the difference between the crew’s ability to sufficiently handle versus the unexpectancy of the cumulative stressors) actually grows increases during the flight, since Unusuality is the difference between the crew’s performed ability to against counter cumulative stressors.

Flight crews encountering severe weather at the final stage of their scheduled duty day require their optimum performance. But because performance levels have decreased with fatigue (poor decision making, slowed reaction time, reduced vigilance, poor communications, instrument scan fixation, apathy, lethargy, mood swings, uncontrolled nodding off), they may not be able to meet operations in demanding conditions at their destination airport. The “unusuality” gap between their collective abilities and the cumulative stressors encountered may be exceeded. As instrument approach minimums are being reached, a flight crew may have mere seconds to detect the runway environment, establish orientation to that runway, transition the aircraft to the landing and then complete the roll-out. There are few other maneuvers requiring such precision, timing, coordination and focus, while offering such stringent demands on flight crews and aircraft systems. Flight crews and airlines expect 100% success in such maneuvers while permitting neither tolerance for failure nor accident regardless of Probable Cause factors resulting from the gap in “Unusuality” factors.

Early morning sun rising through clouds.

Because of the increased use and reliance on automated flight control and navigation systems,[27] flight crews may possess a great ally in dealing with high stressors. Unusuality successfully most nights. But if the automation is not available due to an employment of a non-precision approach runway, lapse in their awareness of actual navigational positioning, or their positioning either laterally or vertically during an approach to instrument minimums, the level of Unusuality could exceed that crew’s abilities and prove hazardous and disastrous. An over reliance on systems that do the “flying for you” may result in degraded manual flight skills that may be needed to be maintained so as to detect the subtle changes in a/c tactile response because of accumulated icing on flight control systems or recover from unexpected windshear or wake turbulence.[28]

A pitot static system malfunctions may be incorrectly diagnosed when a well founded manual flying skill level might have reasonably detected the error and provided suitable systems knowledge and flying skills to correct the problem [29]. On 29 November 1963

Trans-Canada Air Lines Flight 831 a DC-8-54F, crashed at Sainte-Thérèse-de-Blainville, Canada. All 118 on board were killed; the cause was not determined, but pitot icing, vertical gyro failure, and pitch trim compensator problems were suspected. [30]

Negative stressors directly degrade the flight crew in the performance of their duties. With improved methods for identifying the potential of stressors overwhelming normal operations into a zone of Unusuality that may impact a flight, mitigation by the flight crew and dispatcher can be reasonably considered.100_4153

Stressors that combine to raise Unusuality include (partial list):

Fog/Low visibility          Convective weather/TRW             Compressed ATC vectoring

Non-precision approach     Ignoring SOP’s                           Unfamiliar airport                                    High terrain in A/P area      Language difficulties               Fatigue issues

Crew Coordination Errors    Inside-Outside Manuever      Performance MELs                      High intensity ops                 Low time experience                Line training Ops

Night Operations             Flight crew incompatibility           Crew-Dispatcher disconnect

High frequency IMC ops   Information “stovepipes”            Automation Inattentiveness

Environmentals               Vague limitations & guidelines     Runway contamination

De-icing/anti-icing           System complexity                      Uncontrolled Airports


Each of these stressors individually will not cause an aircraft accident, but the cumulative effect will result when two or more elements combine to surpass the crew’s abilities. This cumulative effect will have a “negative synergy” directly impacting and degrading the flight crew’s performance just when the operation may require crew precision and full operational optimization. Demanding operating requirements and diminished safety margins may limit alternative actions by the flight crew because of human or aircraft limitations.

While each “unusuality” stressor may not statistically cause an accident, if the flight crew is required to operate effectively while fatigued, execute a non-precision approach at night in marginal IMC conditions to an unfamiliar airfield, they may have a statistically reduced chance of success for completing the complicated maneuver. When optimal flight crew integration and performance is required for a successful completion, the stressors present may degrade the flight crew’s performance to the point failure .

For example, if given the same non-precision approach with slightly better weather, if the flight crew was experienced, well trained and rested, the chances of success would be greater, At what point in an operation is the safety margin impacted and degraded sufficiently resulting in an accident? Could awareness of causal factors be identified so as to better prepare a flight crew for the added hazard? Could flight crews and dispatchers be better trained at foreseeing such stressors?

100_2933Having just successfully completed Initial Operating Experience (IOE), that flight crew member must now operate optimally as a fully qualified and trained flight crew member. If that level of training proficiency cannot be achieved or maintained, the other crew member will be placed at a disadvantage that may not be fully recognized soon enough during the stressful and demanding final approach phase to an airport in marginal IMC conditions during a non-precision approach. Yet, all flight crews are trained and fully expected to successfully execute such an approach under any condition. There will be an imbalance in flight crew performance when the effects of the “unusuality” stressors combine to further degrade an already taxed flight crew.

Reviewing multiple aircraft accidents produces few unique Probable Causes. Can these Probable Causes be further reduced or eliminated with better training, more effective workforce integration, and improved knowledge sharing?


100_4230Consider the probable cause in a Controlled Flight Into Terrain accident such as Airbus A-300, UPS 1354 at Birmingham, AL, in August 2013.

 The Probable Cause as stated in the NTSB AAR:

“Continuation of an unstabilized approach; failure to monitor aircraft’s altitude”.

The Contributing Causes included;

Failure to configure and verify the Flight Management Computer (FMC), Captain’s failure to communicate with the first officer about the FMC’s failure to capture the FMS constructed glideslope; flight crew’s expectation with regards to airport weather (above minimums), first officer’s failure to make callouts “minimums”, captain’s performance deficiencies, fatigue and distraction; and first officer’s fatigue.

The following “Unusuality” stressors were identified:

Night IMC                     Non-precision approach                 Low hours FO (403 hrs)   Unstabilized approach       Failure of SOP’s                        Fatigue

Dispatch disconnected      Below minimums weather              FMS operation not verified

Authority gradient            Crew coordination                       Inside-Outside Maneuver               Equipment not utilized  Equipment complexity                 Inconsistent manuals

Marginal checkride performance

Underlying the Probable Cause of this crash, these individual “unusuality” stressors probably would not result in a crash in themselves, but it is the authors’ submission that their cumulative effects directly contributed to the Probable Cause(s) thereby resulting in this crash.

  • ) Night instrument conditions
    1. Only the non-precision LOC 18 instrument approach (ILS out of service for maintenance) was available. Less than Visual Meteriological Condition (VMC) existed. The reported visibility was less than 3 miles, broken or overcast ceilings less than 1,000 feet above ground level. Because the flight crew had received the airport report indicating that the ceiling and visibility were above the Localizer non-precision approach minimums, they believed that they would be able to successfully execute the approach and land. Either the company dispatcher or approach controller could have advised the crew that the most recent weather was now below non-precision minimums, but the crew was not aware of deteriorating weather conditions. If the Pilot Monitoring (PM), in this case the first officer had properly programed the FMC for the approach and then the Pilot Flying (PF) had executed the approach to minimums adhering to standard operating procedures, the crew would have then executed a missed approach when it did not acquire the runway at the approach minimums.100_2927
    2. The captain while flying the approach using the FMC observed the system NOT intercept the manually programmed glide path and had to insert his sink rate to catch up and capture the FMC glide path from above. He inserted a vertical sink rate of 1,500 feet per minute (FPM) which violated the SOP Stabilized Approach requirements of no more than 1,000 FPM when below 1,000’ agl.
  • ) The first officer had limited Airbus experience.100_4003_3
    1. The first officer’s did not catch the captain’s error programming the FMC. When the captain continued the approach below Minimum Decent Altitude (MDA), the FO had already failed to call out “1,000 above (MDA)” and then “minimums”. This indicates a loss of special awareness on both the captain and FO as both were now trying to establish the aircraft on the desired The FO was not assertive enough as the approach deteriorated further. The FO questioned the captain’s intentions “Do you want to go around”? Instead of aiding him to make the decision to go around, she had asked him a question while he was conducting the approach, thereby further distracting him in his already stressed state.
    2. With less than 500 hours in the aircraft, she was still acquiring normal flying and crew skills and SOP interaction patterns. The FO, now as the PM would normally not need to direct a more proficient and experienced captain to do something that he did ask for or want. At some point, the approach was becoming more unstable to the point of being unsalvagable with a high decent rate and diminishing airspeed. Well outside of SOP’s (no more than 1,000 ft sink rate below 1,000 ft AGL; airspeed no slower than Reference speed (Vref)). Both excessive decent rate and airspeed below Referenced Speed (Vref) are two distinct callouts required of the pilot monitoring, but were both missed. Because both calls were missed, the effective backup of the PM provided to the PF were missed.
    3. The first officer’s attention was now mainly outside in an attempt to acquire the expected runway approach lights and the PAPI. If the FO had observed the Captain’s excessive decent rate and slow airspeed and then assertively called the captain on it, the captain may have then recognized his deteriorating and precarious position and executed a missed approach. By missing both the captain’s decent rate and slow airspeed, both crew members allowed the aircraft to be placed in an even more unstabilized and precarious position.
  • ) Non-precision approaches are not overly demanding if practiced regularly. Due to the prevailing weather (wind) patterns, most airport approaches are constructed for the ILS, while in good weather conditions, many “visual” approaches are conducted.
    1. When well rehearsed and practiced, non-precision approaches demonstrate flight crew proficiency and coordination. When both crew members know and complete their SOP defined and required duties in this well rehearsed interaction, a demanding but not difficult approach while requiring attention, is not inherently dangerous. Both crew members need to have confidence in the other’s abilities and skill consistency, especially when conducting a non-precision approach.
    2. The Pilot Flying (PF) attention will be primarily inside on flight instruments, while the Pilot Monitoring (PM) will be backing up and verifying the PF’s actions. The PM’s attention will shift from mostly inside (backup of PF) to inside-outside to acquire the runway environment (approach lights, runway end identifier strobe lights, runway, etc.) while the aircraft descends towards minimums. Because this is mostly a PF controlled descent, the PF must integrate his actions and make considerably MORE flight management decisions (instrument course lineup, airspeed, descent rate, altitude until Minimum Decision Altitude (MDA) is reached; observing 1,000 feet and 100 feet above MDA (PM’s callout), approaching minimums, minimums, airspeed, decent rate, aircraft configurations, lineup to course (left or right of course) and checklist completion.100_0308
    3. Note, that when an aircraft is manually flown, for every PF corrective action to place the aircraft in the desired attitude (airspeed) and position (example: aircraft slightly slow, the PF would increase engine power and then when the desired speed is reached must now make a second correction so as to not get fast). If the autopilot is engaged, the auto-trim function will maintain aircraft stability (auto-trim pitch up or down). For every pilot flying correction, there is a required stabilizing second and third correction to maintain course lineup, airspeed and decent rate. PF must continually monitor-correct, monitor-correct, and monitor-correct to decrease aircraft displacements from the desired lineup, airspeed, and decent rate. When done correctly, this monitor-correct technique will result in decreasing oscillations positions. This aircraft-position monitoring is called “instrument scan” where information is visually processed, and then corrections and re-corrections are made.
    4. In an FMS enabled precision ILS coupled approach, the PF’s workload is significantly less and the aircraft’s stability is automatically maintained. Because of automation, immediate corrections to displacements are immediately corrected multiple times per second. Both pilots monitor and verify the FMS and autopilot systems.
    5. Cockpit workloads are significantly more demanding for a non-precision approach with increased workloads at lower altitudes closer to the ground where safety margins are more demanding and critical. The PM must carefully time-manage the duties (inside monitor-outside looking) and backup for the PF. This crew interaction, while executing and monitoring the progress of the approach is a well rehearsed choreography. If the PM spends too much time inside backing the PF, the runway environment will not be detected soon enough. If the PM spends a greater portion of time outside looking for the runway environment, PF deviations in course, altitude, airspeed, sink rate may go unobserved. Mutual confidence in the other’s flying skills and training is critical to execute this critical maneuvering successfully. Like playing the saxophone, it is easy to do poorly.
    6. As a Precision Approach Path Indicator (PAPI) system was available for an aid in landing on RW18 and if seen at approach MDA would have indicated the a/c transitioning from high glidepath, on glidepath, to below glidepath, why the PM detecting the runway environment and PAPI made no reference to the PF remains unclear.
  • ) Ignoring Standard Operating Procedures (SOP’s).101_0216
    1. As Standard Operation Procedures are developed and updated, they provide a source document for operational standardization, training, and checking. SOP’s should match the realities of operations where you would not do something unless it was authorized. But, like speed limit signs on highways, many flight crews will test the boundaries, some partially, others fragrantly. Occassionaly, a flight crew’s failure to comply with SOP’s can be evident in the AAR. Most SOP failures are caused by the flight crew trying to save or make up time on a flight. Some examples include: exceeding 250 kias below 10,000 feet; accepting a visual approach; maintaining higher speed during the approach; taking a closer but less suitable runway; continuing an approach when not stabilized below 1,000 ft AGL; accepting ATC’s direction to “(visually) follow traffic” for landing;
  • ) Unstabilized Approach continued.
    1. SOP’s specify the criteria for a stabilized approach. Flight crews must adhere to those SOP’s and vigorously support their criteria in both word and practice. When ATC attempts to place the aircraft in a position that would infringe on those SOP’s, the flight crew should state that infringement and ask ATC if it was “essential” for safe operations? Examples of infringement: “Slam dunk” approaches”; high and close to airport; following too close an interval on a visual approach; vectors into weather on arrival route; not allowing a delay in the holding pattern for weather to clear; etc.
    2. Flight crews should freely accept “supporting input” from the other FC member when SPO’s are infringed (sink rate too high, approach airspeed outside of desired gates, off centerline on approach, off glideslope, not meeting non-precision approach gates, new influencing weather (tail wind, crosswind component, ground speed change, convective weather). The senior flight crew member should brief the other FC member to point out any observed unintentional SOP’s irregularities and do so without fear of retribution.
  • ) Dispatch Disconnected.
    1. As the Dispatcher assumes equal responsibility for the flight (FAR xxx), the dispatcher should actively monitor that flight until its successful conclusion particularly if negative stressors exist and conditions warrant (weather changes, NOTAMs, weather near or below instrument approach minimums, potentially fatiqued FC’s, etc.).
    2. The dispatcher has access to the destination’s airport or approach controller so as to acquire the most current information to assist the FC. This information can be readily passed to the FC to assist them.100_2930
  • ) Flight Below Instrument Approach Minimums.
    1. Continued flight below the decision height or minimum decent altitude is counter to best practices, yet some FC’s continue such practice occasionally. Open or closed forums “Hangar talk” discussions among pilots concerning such practices should point out how precarious such maneuvers are and how such practices establish examples of negative learning patterns. The costs for such practices should diminish their occurrences.
    2. Some non-precision approaches require the FC to calculate a Visual Descent Point (VDP) after which a missed approach should be executed if the airport environment is clearly not established. F/C’s should freely discuss and clearly understand the importance and inherent dangers if the VDP is passed and a missed approach is not conducted in the misplaced hope of acquiring the airport at some later point.
  • ) Flight Management System (FMS).
    1. Flight crews should use Flight Management Systems, GPS, etc as a tool to assist them and to decrease their en route workloads. These tools aid the FC, and do not take the place of the flight crew. Flight crews should be hone their flying skills as workloads permit. Basic special awareness is important to be maintained so as to detect a mis-programming of the FMS. The impact of operations with MEL out of service or diminished service availability items should be discussed as it relates to the expected flight conditions.
  • ) Authority Gradient.
    1. Junior F/C members should consider how they will effectively interact with the senior FC member and the best practices for communicating. While deference to seniority might be appreciated, the junior member should be encouraged to actively participate in all duties expected from that position including assisting the senior FC member. Full communications and the free flowing of information to add to the safe completion of the flight should be emphasized and encouraged. The F/C should be sensitive to effective communication techniques in order to support full cockpit resource management.
    2. When new crew members first begin flying together, the Captain should discuss the effective communications, overall crew responsibilities and best practices for cooperation. It should be realized that some senor staff/check pilots may be at a disadvantage in trying to maintain required currency because of their staff jobs. All flight deck members should be encouraged to exchange information related to SOP irregularities. While the captain retains absolute authority for the flight, no one is served if an observed SOP error jeopardizes the safety of the flight. should be pointed out and discussed as needed, regardless of rank and seniority.
    3. Recent airline mergers from one-time competitors places added pressure on the effective flight deck communications of now merged flight crews. Company differences and union affiliations need to be minimized, and the preservation of professional safety standards need to be enforced. This will be difficult to achieve in the confines of the closed door flight deck but essential for safety.101_0247
  • ) Crew Coordination. Coordinating flight deck efforts while at altitude while the aircraft is on autopilot are of limited intensity and require only routine coordination. One member flies the aircraft while the other performs navigation and communications functions. Both members back each other up. Routinely, these duties are alternated on each leg of the flight. As the flight intensity and flight deck workload increase during the arrival, approach and landing phases, clear duties and responsibilities as defined in the SOP’s need to be completed with no ambiguities as to whom will be doing what functions and when. While SOP’s define the roles of each pilot, AAR’s indicate repeated errors in execution or lapses in performing those duties remain present.
  • ) Inside-outside duties on approach. Although flight deck duties during the terminal phase are sufficiently defined, the allowable safety margins are critical given the speed of the aircraft, energy-momentum levels (weight of a/c, speed, decent rate) progressing flight path, and closing proximity to the ground.
    1. Although flight deck duties during the terminal phase are sufficiently defined, the safety margins are critical given the speed of the aircraft, energy-momentum levels (weight of a/c, speed, decent rate) progressing flight path, and closing proximity to the ground.
    2. The duties of the pilot flying (PF) when completing a terminal phase of flight while in IMC conditions test the skills and the training of both FC members. The FC’s workload with the autopilot engaged significantly reduces monitoring and PF inputs (observe and verify with no real-time critical action requirement to “do” until either the airport environment is established or the a/c nears approach minimums). If a non-precision approach is being conducted, FC workloads increase significantly as the a/c is flown to a critical position in airspace in relation to the runway (altitude and lineup). The PM must monitor the a/c’s altitude as it approaches the MDA making the appropriate altitude callouts (1,000 above, 400/500 above, minimums) to the PF while the monitoring the a/c’s airspeed and decent rate.
    3. The PM may have only a few final seconds to monitor the PF’s aircraft positioning and a/c’s momentum, while also trying to sufficiently detect the runway environment. Once the runway environment is detected, suitably recognized (left or right of runway centerline and positioning on a visual glide slope (VASI/PAPI), this must be quickly and accurately conveyed to the PF. The PF must now leave the inside instrument scan to now acquire the runway environment, VASI/PAPI glideslope positioning, and then transition the a/c to land; ALL within the safe parameters of kinetic energy and a/c trajectory., When landing is accomplished, determine if the touchdown point is sufficient to allow the aircraft to safely stop within the remaining runway. The PF must manage the a/c’s trajectory and deceleration to a safe taxi speed is attained given the conditions of the runway (wet, standing water, braking action, packed snow, grooved/non-grooved, wind velocity and direction, and the a/c’s hydroplaning characteristics).
  • ) Equipment not utilized
  • ) Equipment Complexity, Inconsistent Manuals


From Wikipedia on line

  • “Airlines Flight 1354 was a scheduled cargo flight from Louisville International Airport to Birmingham–Shuttlesworth International Airport. On August 14, 2013, the aircraft flying this route, a UPS Airlines Airbus A300-600F, crashed and burst into flames short of the runway on approach to Birmingham–Shuttlesworth International Airport in the US state of Alabama. Both pilots were pronounced dead at the scene of the crash. They were the only people aboard the aircraft.
  • Aircraft: The aircraft involved in the accident was an Airbus A300F4-622R, registered as N155UP. It was built in 2003; UPS took delivery of it in February 2004. It was powered by Pratt & Whitney PW4000 At the time of the accident, it had accumulated approximately 11,000 flight hours in 6,800 flight cycles (takeoff-and-landing sets).100_3975

Crash: The aircraft crashed at about 04:47 local time (CDT, 09:47 UTC) on approach to runway 18 at Birmingham–Shuttlesworth International Airport. It clipped trees and struck ground three times uphill. The fuselage broke apart, with the nose coming to rest about 200 yards (180 m) away from the initial point of impact, and the rest of it about 80 yards (70 m) further down towards the runway and about 1 kilometer (0.6 mi) from its edge and catching fire.

Investigation: The National Transportation Safety Board (NTSB) launched an investigation and sent a 26-member “go team” to the crash site to “collect perishable evidence”. At a press conference held later on the same day, the NTSB said they had been unable to recover the cockpit voice recorder and the flight data recorder as the tail section (where the recorders are housed) was still on fire. Both recorders were recovered on the following day, and were sent for analysis.

On August 16, 2013, at their third media briefing, the NTSB reported that the crew received two GPWS alerts “sink rate!” (that they were descending too quickly) 16 seconds before the end of the recording. Three seconds later, one of the pilots commented that they had the runway in sight. Nine seconds before the end of the recording, impact sounds were audible. The crew had briefed the approach to runway 18 and were cleared to land by air traffic control two minutes prior to the end of the recording. The captain was the pilot flying, and the autopilot was engaged at the time of the accident.

To represent the country of manufacture, the French aviation accident investigation agency BEA, assisted by Airbus technical advisors, participated in the investigation. Members of the FBI Evidence Response Team also assisted the NTSB. The NTSB stated in late August that no mechanical anomalies had been uncovered to that point, but that the complete investigation would take several months.

On February 20, 2014, the NTSB held a public hearing in connection with its investigation. At that hearing, excerpts from the cockpit voice recorder were presented, in which both pilot and co-pilot discussed their lack of sufficient sleep prior to the flight.

In 2014, the Independent Pilots Association filed suit against the FAA to end the cargo airplane exemption from the flight crew minimum rest requirements.

101_1078On September 9, 2014 the National Transportation Safety Board announced that it had determined the probable cause of the accident was that the aircrew had continued an unstabilized approach into Birmingham-Shuttlesworth International Airport during which they failed to monitor their altitude and thus inadvertently descended below the minimum descent altitude when the runway was not yet in sight resulting in controlled flight into terrain (CFIT) approximately 3,300 feet short of the runway threshold. The NTSB also found contributing factors to the accident included: 1) the flight crew’s failure to properly configure and verify the flight management computer for the profile approach; 2) the captain’s failure to communicate his intentions to the first officer once it became apparent the vertical profile was not captured; 3) the flight crew’s expectation that they would break out of the clouds at 1,000 feet above ground level due to incomplete weather information; 4) the first officer’s failure to make the required minimums callouts; 5) the captain’s performance deficiencies likely due to factors including, but not limited to, fatigue, distraction, or confusion, consistent with performance deficiencies exhibited during training, and; 6) the first officer’s fatigue due to acute sleep loss resulting from her ineffective off-duty time management and circadian factor.” Note: Wikipedia footnotes omitted, but are in the referenced original text.

However, let’s take another look at the mishap of UPS 1354.101_0241

We will list the Negative Stressors, when the stressors were known and by whom they were known:

  1. Night flight ops; scheduled; all knew including tower ATC operators and airfield maint.
  2. High terrain in approach corridor; charted; all knew
  3. Crew fatigue due to night scheduling; scheduled; well known industry fatigue issue
  4. Additional fatigue vector-crew was not feeling rested enough to perform well; crew discussed in flight; crew knew
  5.  Weather reported above mins at 1000 feet, actually 200-300, below mins, misleading them to believe they were 1000′ agl when they broke out of overcast.
  6. Non precision approach. Published, but crew might have been expecting the ILS. The non precision approach was known by all well before the mishap, but as the name implies, it lacks the glide slope precision information that is critically important in the Category two and three ILS certification for which this plane and this crew were qualified. The Cat II/III runway was not available due to an electrician changing light bulbs on that runway. It was never determined if this was scheduled or non-scheduled maintenance, although a notice to airmen was published. It should be noted that the arrival times for UPS 1354 are also published at least two months in advance and therefore well known to the local ATC office and airfield engineering.
  7.  Ineffective CRM, PF was doing it on his own putting in high sink rate to get down to MDA after FMC didn’t engage. Known after from CVR
  8.  FC violated SOP for a stabilized approach, over 1,000 fpm decent under 1,000 ft agl. CVR
  9.  PM didn’t call out callouts CVR
  10. PM was outside (looking for lights) and inside (trying to backup PF and make callouts) CVR
  11.  Pilot-Dispatcher disconnect, dispatcher didn’t give help with weather. While the weather was called as 1000 feet above field elevation, in the RW 18 corridor, it was between 200 and 350 feet above the ground level.
  12. Airport did not do a decent threat analysis on light maintenance on ILS vs. crew coming in in bad weather for a non-precision from scheduling information known 2 months in advance.

Figure 1. Impact of Accumulated Known Stressors, UPS 1354, is a pictorial depiction of this idea, remembering that stressors may not individually be considered hazards to flight in and of themselves. However, in the accumulation of stressors, we may have found that the accumulation itself may be a new unrecognized hazard, the one ultimately overwhelming the crew. 














What do you think?

Could it be that by looking at the sum total of the negative stressors, we may find that real hazard that led to the UPS 1354 mishap? In so doing, could we find a pattern of crew overload, an overwhelming of the crew ability at any one point in time? Could this be the area that flight safety managers need to look at next to bring the commercial airline mishap rate closer towards zero?


Collectivity of Mishap Causes as a separate issue.

In our study of multiple commercial aviation mishaps[31], the mishap investigation boards publish what appears to be a listing of probably and contributing causes, each listed singularly. The purpose of listing the causes singularly is so that the authority, agency or organization accountable for making changes to equipment, procedures for interacting with the flight environment and standard operating procedures that humans use, can address each cause with an action to prevent the same mishap from occurring again.

However, we noticed that in each boards mishap investigation report, that there was also a collectivity of causes, a set of cascading facts, an accumulation of events, that could be derived by looking at reporting patterns of the investigators. Further, as commercial airline pilots we recognized that in many mishaps, the collectivity of mishap causes, in and of itself, in addition to singular and individual causes, seems to overwhelm the crew. If they did not make the right decision immediately in reaction to the events, subsequent events began to pile up, accumulate and eventually overwhelm the crews’ ability to react to successfully bring the aircraft to a safe landing.

In the USAir 1549 Airbus landing on the Hudson River, the crew was faced with a set of negative stressors, but through superior crew ability landed the aircraft in the water allowing the survival of every person on the flight.[32]

In the United 232 DC10 landing in Sioux City, Iowa,[33] and the Ethiopian Airlines 962 B767 mishap in Tanzania[34], the crew exhibited superior ability in the face of overwhelming negative stressors, allowing many onboard to survive what could have been totally fatal mishaps. The level of Unusuality reached a very small positive value in the final few seconds of each flight causing the landings to be high speed and resulting in airframe break up. However, the crews stayed ahead of the negative stressors right until the last moments and as a result, the level of Unusuality was very small.


In other mishaps, the crews were certified, fully trained and qualified according to the standards of the day, yet the accumulation of negative stressors in and of itself, and not just each individual cause, may have overwhelmed the crews’ ability to react to successfully bring the aircraft to a safe landing. One popular view is that when viewed individually, each negative stressor is manageable and therefore the crews could have saved many of these flights. However, this is not our argument, since the authors looked at the mishap reports from the viewpoint of collectivity of mishap causes. From this view, a straw can break a camel’s back. [35]

In Swiss Air 111[36] off Nova Scotia, in Singapore 006[37] at Taipei, in Southwest 1248[38] at Midway, Chicago, in Alaska Airlines 261[39] and in American Eagle 4184[40] the crews were faced with a set of accumulative negative stressors that occurred simultaneously or in very quick succession and appear to have overwhelmed the crews’ ability to react successfully.

In Swiss Air 111, incorrect design, engineering, documentation and procedures were occurring, as an electrical malfunction became a source for fire. Negative stressors exceeded the crew ability and created a positive level of Unusuality.

In Singapore 006, a swirling typhoon rainstorm blanked out visibility. This prohibited the ATC tower controller from observing that of the two sets of operating green taxiway lead-in lights were lit, one to the correct runway and one to a runway closed for construction and occupied by heavy equipment. The construction was also invisible from the cockpit due to rain. Singapore 006 crew had inadvertently followed the lights to the closed runway and begun takeoff. The negative stressors accumulated past the crew’s and ATC controller’s ability at that time and created a positive level of Unusuality.

In Southwest 1248, the crew was faced with a runway in snow with a tailwind and lacked familiarity with some aircraft systems. Stopping distance calculation procedures used available thrust reverse, which if unused or unavailable could prevent stopping in slippery conditions. In all, the tailwind, snow and questionable calculations, along with the misuse of thrust reversers accumulated negative stressors greater than the crew ability at the time to react and resulted in a positive level of Unusuality,

In Alaska 261, the crew, by attempting to discern a way to reestablish pitch control after the pitch control systems malfunctioned, and unaware that their actions added to the accumulating negative stressors, which included incorrect maintenance procedures, eventually became overwhelmed when the damaged pitch control system totally failed causing a subsequent unrecoverable aerodynamic longitudinal stability failure. So there was both a stability failure and a control failure occurring at the same time, as the failed jackscrew that adjusted pitch control, also held the horizontal stabilizer in position.

In American Eagle 4184, the crew was placed in an area of icing to hold. The airframe icing buildup that was investigated was downstream of deicing systems but upstream of aileron controls. The weather was IMC with icing, it was night time reducing visibility, no engineering or test data documentation was available for long term in-flight icing exposure, no limit-time existed in FAA ATC regulations for holding in icing conditions. Meteorological ability to discern levels of icing between light, moderate and heavy were dependent upon a calculative synthetic estimate of flight level precipitation and freezing temperatures and therefore only advisory in nature to ground stations such as ATC and dispatch. The negative factors, all known about ahead of time, accumulated during the flight of AE4184 and overwhelmed this crew’s ability to react in a manner to successfully control and land the aircraft. Unusuality in this case existed because the sum of the negative stressors exceeded the crew ability.

In Executive Airline (doing business as American Eagle) 5401 mishap[41] in San Juan, many crew-training issues came to light, but training is based on procedures. The board determined that bounced landing procedures and thus training was insufficient to address the circumstances when an ATR 72 landing bounce occurs. The crew ability was a vector of a lower magnitude than the vectors of the negative stressors on this flight. While the flight was not a training flight, the pilot flying has recently completed IOE training, but that training did not include bounced landing procedures. This is an example where the crew ability was low and the negative stressor vector exceeded the ability vector resulting in positive Unusuality.

The mishaps were the result of an accumulation of many negative stressors, negative factors whose vectors collectively far exceeded the crew ability at that time to successfully land the aircraft. The collectivity of the mishap causes and not just each cause individually may be an important unaddressed factor in commercial aviation mishaps.


Recognizing Known or Knowable Negative Stressors

Each of the negative stressors was either a known fact before the mishap or it was a knowable fact before the mishap. In each of the mishap board investigation reports, each probable cause and contributing cause listed for these mishaps was either known or knowable before the mishap.[42] [43] [44]

Some may argue against this known or knowable claim concerning the ice horn build up discovered in testing after the AE4184 mishap, [45] [46] citing the tests as the source of knowledge and the date of the testing subsequent to the mishap.

Quite to the contrary however is the fact that super-cooled particle physics is not a new subject and has been known thermodynamically for a very long time. [47] Noted physics writers Halliday and Resnick describe super cooled liquid physics in their text earlier published in 1962. Super cooled liquids changing phase into solids without an intervening loss of heat energy normally associated with phase change from liquid into solid is described. The danger of flight into rain, water that has cooled below the normal freezing temperature is that upon phase change, the volume of ice created by the freezing water in much higher than the build up of ice that has already formed in the atmosphere, since ice by volume is greater than water by volume at the same weight. [48]

While testing may have employed ATR 72 aircraft parts to determine the exact nature of the icing build up, the physics of massive ice build up due to impact with super cooled liquids was a known fact well before the mishap and thus was a knowable negative stressor in existence before the mishap occurred. Would the variation of different crew members on that flight changed the rapid build up of super cooled water into ice on the ATR 72 airframe the night of the mishap? The way to prevent the build up of super cooled water into ice would have been to avoid flight into that area of precipitation. Since the crew was directed into that area by ATC, should does ATC have a responsibility to know knowable facts, such as where in the control area are conditions for super cooled rain, known as freezing rain likely to exist. Could the airline dispatcher, who also had access to and knowledge of real-time meteorological data adjusted operating procedures such as flight plan to avoid freezing rain areas?

The freezing rain occurrence and consequence to flight safety was known and knowable before the mishap.

In Asiana 210 at San Francisco, in Korean Air 801 at Guam and in UPS 1354 at Birmingham, for a variety of reasons, the precision ILS equipment was withdrawn from service and unavailable to the crewmembers. Crew members were operating very large aircraft filled with passengers and had multiple human factors issues such as language spoken not being English as a first language, fatigue due to long operating periods, in two cases at night in areas of terrain above the field elevation. In all three cases, the aircraft and the airfield were capable of very precise and sophisticated automated landings. The automated landing technologies for plane and airfield had been developed to improve commercial flight safety. Locally at those airfields, a decision was made to withdraw that equipment from service. No longer would this technology for safe flight be used. Instead, the ATC manager substituted much older and less effective airfield avionic equipment, lacking electronic glideslope information critically required to allow the crew to couple the aircraft autopilot systems to the airfield equipment. This was initiated with just the minimum of notice to airmen. The airline choose to dispatch these flights knowing that the latest technology was out of service and the airfield ATC managers choose to continue commercial flight operations knowing that the latest technology had been withdrawn from service. Because these were long flights and conducted during circadian low cycle times, crew fatigue is a negative stressor, whether or not recognized by the investigating board. [49] [50] [51] [52]

Operating demands in these circumstances increased very significantly while the negative stressor vectors of fatigue and other factors affected the crew ability. In these three cases, the negative stressor vectors surpassed crew ability and the positive vector of Unusuality occurred.

In the KLM 4805 and PanAm 1736 twin B747 disaster at Tenerife, negative stressors once again began to add up.[53] Weather visibility prevented visual ATC confirmation of aircraft movement around the airfield and prevented aircrew in each aircraft from seeing other aircraft moving about the airfield. Earlier diversions of large aircraft had overburdened the parking and taxiway areas of the airport. Since many flights were long distance operations, crew duty day and fatigue issues added negative stressors. English spoken as a second language was a human factor negative stressor vector. In addition to the overburdened surface movement area, the radio frequencies available for usage were overburdened, resulting in more than one aircraft transmission occurring simultaneously, this causing some aircraft receivers to not process the multiple transmissions clearly, this resulting in miscommunications and missed communications. Once again, the mishap boards investigating this enormous disaster cite many probable causes and many contributing causes.[54]

Our study though looks at the cumulative effect of all of the negative stressors and compares that to the crew ability available at that time. For ATC and the crew of KLM 4805, the level of negative stressors surpassed their abilities and a positive value for Unusuality occurred. However, each investigation found factual evidence that was known or knowable at the time of the mishap. For example, the crew of KLM 4805 was able to hear the multiple radio transmissions between ATC tower and other aircraft moving on the airfield under tower control. Even though there is not direct procedural requirement for any crew to monitor communications with other flight crews, the communications between tower and Pan Am 1736 were received by KLM 4805 and were knowable. In addition, both tower and Pan Am 1736 transmitted information that contained location information on where Pan Am 1736 was, and the radio traffic clearly stated the location of Pan Am 1736 as being taxiing on the same runway that KLM 4805 was holding in position for departure[55]. The mishap investigations did not discover any fact that was not already known or knowable to the crew of KLM 4805. The tower radio transcript and the cockpit voice recorder transcript for Pan Am 1736 [56] clearly show that the crew of Pan Am 1736 knew that KLM 4805 was anxious to depart and may have already started take off roll without explicit tower authorization. The level of negative stressors in this case impacted the crew of Pan Am who were aware of ATC communication irregularities with KLM 4805 and despite their best efforts and abilities, were overcome by the compilation of negative stressor vectors and fell victim to a positive value of Unusuality.

At Buffalo, many negative stressor vectors added up to a value greater than Colgan Air 3407 crew’s ability. CRM and crew aircraft handling training were very weak vectors. Nighttime ops and crew fatigue were negative crew ability vectors. Unusuality became a positive value due to very low crew ability values. [57]

By contrast, the crew of American 1420 at Little Rock was well trained and experienced in procedures.[58] However, the demands on the crew grew well above normal ops when they arrived at the scheduled airfield in the midst of severe thunderstorms, during night operations, requested and were cleared to land on a rain contaminated runway with a very strong crosswind, no headwind and possibly a slight tailwind. While the crew delayed opening thrust reversers and did not deploy wing spoilers in either auto or manual mode, other negative stressors may have added vectors in the wrong direction.

For example, when the American Airlines dispatcher looked at the local radar remotely at the airline hub in DFW, was the dispatcher seeing calculated rain decibel return or wind field data? Again, in reviewing the NTSB AAR, the causes related to the aircraft loosing directional control and being unable to stop were related to the wind field on the runway at the time. While rain contaminated the crowned and grooved runway, reducing runway tire friction, was not the wind the actual physical force the moved the aircraft? From Newtonian physics,[59] forces can only be made by bodies and in this case, the body was the wind field of moving air. It was not the rain that moved the aircraft but the wind. Yet, the dispatcher was advising the flight crew based on data of the rain. The windfield data was loosely available to the dispatcher who could have calculated a wind field by comparing observed surface magnetic winds and 3000 foot true forecast winds, as well as charting observed surface wind changes being reported regularly. But instead, the dispatcher used reported radar rain data to advise the crew on a safe course of action. The crew could well have made the decision to hold or divert to a clear airport near by, citing negative stressor vectors as exceeding their abilities to land successfully at that time. However, they did not self diagnose the growing positive Unusuality.

Why? Did this airline or any airline have a self diagnosis procedure whereby flight crew could determine that the level of negative stressor vectors had exceeded their abilities at that time and they needed to pursue an alternate course of action, rather than allow Unusuality to affect their safety and the successful landing of their aircraft.


What would a Recognition Metric for Unusuality look like? If a recognition metric could be developed, could some procedural adjustment method be developed to intervene quickly to prevent a commercial aviation mishap?

 A recognition metric for Unusuality would have to take into account several elements that have been discussed above:

  1. Collectivity of Causes as a separate issue:

The cumulative affect of many multiple probable causes and contributory causes identified in so many of the commercial mishap in the Williams and Miller Study of Commercial Aviation Mishaps Causes informs us that the goal of a recognition metric is to look for things that affect the people involved, the equipment involved and the flight environment. A working metric has to be looking at all three areas for hazards that are occurring at the present time and thus have been occur, at least since the recent past. The metric must be able to measure all of these hazards in some quantitative fashion, even if that methodology estimates the values of the hazards or negative stressors.

  1. The metric must be able to recognize negative stressors as vectors, that is, a value with both size and direction. It must be able to recognize that which is working against the crew and by how much. It should be remembered that negative stressors were in existence at the time of the mishap, were either known or were knowable facts, according to the NTSB and other boards who were able to find them as existing facts at the time of the mishap, weeks and months after the mishap.
  1. The metric must be able to identify whether the crew ability is 100% normal according to the standards for that airline, or whether the crew ability is diminished by human factors such as normal fatigue, or whether the crew ability is affected by strong, normal or weak levels of training as defined by the standards of that airline. The metric must be able to assign a quantitative number to represent the level of crew ability, perhaps in terms of 100% or some other value that is consistently applied by metric to all crewmembers at that airline.
  1. The metric should be able to classify a particular operation as normal for that airline, easy or perhaps more difficult than normally encountered. Again, a value system using percent as determined by that airline would be most applicable and useful.
  1. The metric must next be able to quantitatively compare the level of negative stressors as they are known or should be known to be occurring and affecting a particular flight, with the crew ability at that time for that flight. As long as the crew ability remains greater than the accumulative vector level of negative stressors, then the operation can continue using normal SOP. If training is effective and applicable to line operations, this case should be the predominate condition day to day.

6, However, in the few and rare cases when the crew, the dispatcher, the chief pilot or other authority determines that the negative stressor vectors are at a value that begins to exceed the current crew ability value, then the metric must be able to identify that a positive level of Unusuality is occurring. This means that hazardous conditions are occurring during this flight operation. This method differs somewhat to other quality assurance and risk assessment systems because the values being compared normally fluctuate throughout the day due to diurnal and nocturnal fatigue and by so many other factors that could increase or decrease both the value for crew ability and for negative stressors. It is a value dependent on comparing a series of variables with each other and understanding that value as acceptably normal or unacceptably unusual, possessing Unusuality.

  1. The pay-off however for this Unusuality Recognition Metric comes when the local flight authority, the team of crew and dispatcher or even the crew individually determines that there is a reason to make an adjustment to operating procedures that will bring the level of Unusuality back to zero or a non-positive value and thus prevent a mishap from ever occurring.


Of course, everyone would expect a standard formulation at this point to take home and plug-in to their flight operation. However, since safety at each airline is the result of effective locally applied programs to identify hazards and take quick action to eliminate them, the actual metric will have to be locally developed in order for it to be effective at each airline. There is no standard formulation, but there is an example below of how to create a metric for your airline.


The most important thing to remember is that negative stressor vectors are cumulative in nature and therefore, in order for the metric to work, it must measure negative stressor vectors that affect people, equipment and the environment.


Example Recognition Metric for Unusuality.101_1079

Here is an example of how a Recognition Metric for Unusuality could be created and applied in the case of the Air France 447 mishap that occurred off Brasil in the Atlantic Ocean area known as the inter-tropical convergence zone.

  1. What were some of the collective causes listed in the mishap report?

1.1 The environment: The report listed that weather in the inter-tropical convergence zone often contained very large areas of convective activity, both in terms of heights of clouds reaching 50,000 to 60,000 feet and areas of clouds with diameters in excess of 50 miles and in some cases much longer. This is a known negative stressor because the manufacturer, the regulator and the airline procedurally recommend avoiding thunderstorm activity.

But at the airline dispatch office, where real-time satellite photos were regularly on display, and at this time an area of thunderstorms reaching heights in excess of 50.000 feet stretching over a diameter of 70 miles along the planned and known flown flight path of AF 447, no communications rerouting the flight around the area of severe weather were calculated, communicated to the flight or investigated by the dispatch office with the ATC agency controlling that airspace. Add the negative stressor of night operations, where in the crew could not visually pick their way through an area of storms or visually recognize that there was no viable path other than to circumnavigate the area of convective weather.

Flight path deviations in oceanic zones are procedurally acceptable as a normal procedure coordinated between the controlling agency, the crew and the dispatch office.

1.2 Equipment: The Airbus 330 was a very solidly built transport aircraft, capable of withstanding g-forces, icing, wind gusts, lightning strikes, small hail and other hazards associated with inadvertent flight through thunderstorms. However, intentional flight through an area of 50,000 foot tall thunderstorms 70 miles wide, a transit which would last about 15 minutes at a cruise speed of 450 knots is not recommended because hail can reach size and hardness significantly damage aircraft leading edges, antennae, wind screens and engine fan and compressor blades. In addition, there was a known problem with the pitot static system installed on the aircraft, a problem of it malfunctioning in frozen precipitation. AF 447 was filed to fly at flight levels where any precipitation would be frozen precipitation. Losses of the inputs from the pitot system were known to cause considerable disruption to the computer-based management of flight on the AB 330. This was a known problem as loss of the pitot system on any transport aircraft is a considerable in-flight equipment problem.

1.3 People: The crew was well trained by Air France standards. The dispatcher was well trained by Air France standards. However, the captain left his station to two qualified crewmembers before the flight entered the inter tropical convergence zone. Since the zone was known to possess the potential for massive thunderstorms, perhaps it would have been a good idea to remain on the flight deck while the flight transited the zone. The other crewmembers appeared to be trained to respond to various warning and caution systems that began to go off, however they did not appear to be well trained in the procedure for loss of flight instruments. They also kept the aircraft nose raised during the stalled condition, which indicates that their aircraft handling training for such things as aerodynamic stalls was very weak. Lastly, the dispatcher showed little concern nor initiative to improve the safety of the flight by taking some actions to advise the crew of the hazardous weather ahead nor actions on how to avoid it. Was the dispatcher thinking of the welfare of the hundreds of passengers and crewmembers onboard AF447? Even if the flight made a successful transit of the severe convective weather area, the ride would have been very rough, uncomfortable at best, but also very hazardous to people not buckled in firmly with seat belts at worst.


  1. The negative stressors as vectors: When taken collectively, the known negative stressors in the flight of AF 447 added to a very big quantitative number. In addition, every negative stressor was known or was knowable ahead of time. The BEA report identified causes that were all known or knowable at the time of the mishap, thus these were facts existing at the time of the mishap and thus existing before the mishap occurred.


  1. The crew metric could be considered 100% trained and ready by the Air France standards. Possibly fatigue was affecting the captain, who self diagnosed and chose to take a nap after the aircraft was established on its oceanic track. Since there was a question about the crews aircraft handling ability, it would be fair to set he crew ability at perhaps 90% instead of 100%.


  1. The airline operation challenge for AF 447 could be considered normal, yet any transoceanic long-range intercontinental flight through the intertropical convergence zone is a level above the challenge of an intercity continental flight. The qualifications for this flight require extra procedures training and three crewmembers were assigned because of the long duty day. If a normal intercity flight were to be at a 20% level challenge for Air France, this flight would easily be considered twice that at the 40% challenging level.


  1. The comparison between the negative stressors, the operational challenge and the crew ability. Since the crew was totally qualified to operate this flight successfully and other crews similarly qualified had successfully operated this flight many times, it can quantitatively be stated that the crew ability was in excess of 40% and appeared to be at about 90 % from number three above.

However, when the collective negative stressors are added together as vectors and compared with the crew ability, it appears that the collective negative stressor exceeded the crew’s ability to successfully complete the flight. Does this mean that negative stressor for which they were ill prepared to handle overwhelmed the crew? Perhaps the crew ability should be moved lower to 80% or 70 %?

Does it mean that the collective negative stressors were so great that they overwhelmed the crew whether they were at 70, 80 or 90%? Did Unusuality occur, in that the value of the comparison between negative stressors and crew ability was positive and sizable? Was the crew not sufficiently trained or was the crew overwhelmed by Unusuality?


  1. Did the pitot system malfunction, the entry into a massive area of thunderstorms, the failure of the dispatcher to assist the flight, the absence of the captain initially from the flight deck, the crew’s poor aircraft handling ability collectively combine to overwhelm the crew’s lowered ability to successfully complete the flight operation?


  1. If the Recognition Metric for Unusuality has been successfully developed in steps 1-6, it is clear that each fact discovered by BEA was a fact and thus discoverable before the mishap occurred.


If Unusuality is a recognizable and measurable comparison between known or knowable facts before a mishap occurs, an adjustment of operating procedures could be made to avoid mishap’s occurrence even before it occurred.

One example would be for the airline to require the dispatcher to adjust filed flight paths for flights transiting the intertropical convergence zone when convective weather blocks their filed route. Another example would be for the regulator to require more immediate responses to known equipment hazards such as pitot systems known to fail in icing conditions. Another example would be for the airline to tailor their minimum equipment list or MEL for equipment needed on a particular type of flight such as a transoceanic flight through the intertropical convergence zone.

Another example would be for the airline to adjust procedures to require the captain’s presence during transit of forecast or known severe weather areas. In addition, there appears to be a need to improve aircraft handling training at this airline to include stall training and flight with inoperative flight instruments.



IN CONCLUSION, there are three things to keep in mind.

1. This is one of our most innovative projects ever. Why? Here is why. Past mishap prevention procedures focused on hazard elimination. Hazard elimination works well and has helped us move forward up to this point. We continue to espouse hazard elimination as an important safety strategy.

But, we have found another “non-hazard” hazard lurking in plain sight. It is the overwhelming of flight crew members by negative stressors! Each negative stressor might not necessarily be classified as a hazard to flight by the current risk analysis methods used by most airlines.

However, when negative stressors are heaped together, they can build to the “tipping point.[1]” In remembering the book, “The Tipping Point: How Little Things Can Make a Big Difference (2000), by Malcolm Gladwell[2] negative stressors can combine to overwhelm crew members. It is very much like   the story about “the straw that broke the camel’s back.” It wasn’t one straw or another that was the problem. Straw isn’t a problem. Negative stressors might not necessarily be considered hazards. It was when too many straws were placed on a perfectly good camel, the camel was just overwhelmed his ability to carry it all and collapsed.

It is the same way with flight crew. One day everything is fine, the flight is a success and they perform well. The next day so many things happen at once, all needing an immediate or relatively rapid response and the crew is overwhelmed and fail. This is what happened for example to AF 447, UPS 1354, KLM in Teneriffe, Swiss 111.

All of these crew members were successful and capable. But one day too much was served on their plate and they choked on it all. If you listen to Captain Sullenberger’s voice from the ATC broadcast tapes[3] and cockpit voice recorder, you can hear a guy speeding up his talking to two or three times his normal word per minute rate. He is not excited in tone, but he certainly is using his increased word count to communicate, giving him and his copilot time to set up and talk over options. He does not allow Laguardia Departure ATC to draw him into a prolonged discussion of what are now becoming irrelevant options. He does not issue a mayday call nor does he squawk mayday with his transponder. He knows now that no one can help him, he needs to do what needs to be done. He becomes his own rescuer. Once he landed safely, he said, “then we all needed to be rescued.”[4]

What is also notable to me is that ATC is baffled and eventually drops out of the conversation almost dumbfounded. But another voice on the frequency states, “I think he said that he is landing in the Hudson.” I believe that the comments are from the flight crew of another flight airborne on the same frequency, who grasp immediately Sully’s game plan and attempt to translate it to Laguardia Departure. [5]

So that is the first important insight. The crew one day is operating fine and the next day crash. Same crew, same plane, same operation. If a tipping point of negative stressors is reached or exceeded, the phenomena of Unusuality appears and can hazard safe commercial flight.

2. Second, each of the NTSB reports we reviewed in our study had one very important and common element in them: they all list somewhere in the report, numerous probable causes and contributing causes. Some reports listed between ten and twenty things that went wrong. Yes, the mishap board reports cite probable and contributing causes numbering often in the double digits!

What does that mean to us? For one thing, the crews of the mishap planes were having to deal not with just one hazard, one thing wrong , one negative stressor. No indeed. They were having to deal with ten to twenty things wrong and deal with them all at the exact same time. Isn’t that really what each of these NTSB and other board investigations state, whether they do so knowingly or unknowingly, when they issue their lists of probable and contributing causes? Yes? No? If not, how else could the causes be related to the mishap?

Each of these reports, in some cases ten to twenty probable and contributory causes, if they are indeed valid as causes, as the mishap board have stated they believe them to be the case, then each of these causes represents a problem, a hazard or a negative stressor that the crew was facing and to which they had to respond at the time of the mishap occurrence.

If indeed these after accident report are correct, and we have no reason to argue that they are not correct, then what the boards are stating is this: numerous things, in some cases, ten to twenty things went wrong at about the same time, that is, the time of the mishap, that the crew had to confront. The CVR and the DFDR, and the tower tapes and all the other factual evidence in all the reports, document a strangely similar set of events in each mishap. It is this: the crew members were faced with an large simultaneous set of issues that wound up overwhelming their ability to cope. It is that simple. The level of negative stressors exceeded their ability at that time. So to understand this, you have to understand that there are two variables. One is the level of negative stressors and the second is the ability of the crew at any given point in time. This can and does vary up and down. In the case of UPS 1307, a DC8 with an onboard fire, the crew ability exceeded the negative stressors and they successfully landed the aircraft in 2006. Yet four years later the crew of UPS 6 with a similar fire was overwhelmed and failed.

“The overwhelming” became the new hazard and became the reason for the mishap. It is not the individual items, no matter how important each sounds individually, in and of and by themselves.

They were just overwhelmed by events, overcome by events or OBE. They just could not stay ahead because they were faced with too much all at the same time. In the case of UPS 1354, if the weather actually had been 1000 overcast, they would have been fine. If the runway was the main ILS, they would have been fine. If there was not high terrain out there in the approach corridor, they would have been fine. If they were not so fatigued, they would have picked up in the errors and been fine. But when all of this is added together, it just overwhelmed them. The things going awry were not all hazards even, just unusual set of facts that collectively combined to swamp the crew.

3. Here is the third thing. When we were flying international, we often had a standards pilot, company check airman, training guy ride with us, often as once or twice a month. Part of it was that it seems just about every gateway airport has a unique procedure set that they use that no one else uses and is not written down anywhere. Or they have written set of procedures again unique, that you plan for, but that they do not use. The line check guys ride along it seemed, more to point out these peculiarities and discuss them with you, not so much to check you on it.

Flying Europe, the Americas and Asia routes,  the check airmen’s insight was valuable and appreciated. The experience was always positive and two way, in our recollection. Okay, now here is the thing we have been leading up to. If the company could schedule all of these check airman flights and for good reason, why couldn’t they find a domestic flight with a heightened level of Unusuality, where the pilots are dead tired, the weather is down, the ILS is out, the terrain is rising, the copilot is new, the captain is doing his best, but so much is stacked up against the crew; why not just throw one of these check captains on the flight for the ride out early in the morning? Why not just add a third pilot, another set of eyes, someone to discuss with them a procedure that they seldom if ever use? What harm would it do?

If the company has enough check airmen, why not have them ready to ride when Unusuality is measured to be high on a particular flight? The company could have enough check captains to ride along with Unusuality indicated flight crew and point out the finer points of running the FMS through a discontinuity for a NP approach in the mountains, at night in the fog. Why not consider this? It would be good training and help overcome the huge clear case of Unusuality that could now be easy to see,

Some may say, “baby sittng.” But is it baby sitting in to have additional standardization flights or line observation flights? Which is cheaper, one check crewman or a crew, a plane and all lost in a mishap?



[3] Miracle on the Hudson;;_ylt=A0LEVvvCTG1VP3oARUUnnIlQ;_ylu=X3oDMTEwNzJpNmJwBGNvbG8DYmYxBHBvcwMxBHZ0aWQDBHNlYwNyZWwtYm90?ei=UTF-8&hsimp=yhs-001&hspart=mozilla&fr=yhs-mozilla-001&p=miracle+on+the+hudson+audio&fr2=14166



In Summary:

Unusuality can be known ahead of a mishap because it is a comparison of facts known or knowable before a mishap occurs. This observation is the result of studying dozens of commercial airline mishap reports from NTSB, BEA and other mishap investigation agencies. Unusuality exists because the probable and contributing causes for mishaps combine to overwhelm crewmembers ability at the time of the mishap. Crew ability is also variable value, with changes coming from fatigue, training, crew resource management, communications ability, managerial ability, the ability to recognize negative stressors both individually and collectively in comparison to the crew’s current level of ability.

If Unusuality can be recognized, it can be recognized ahead of a mishap occurring if the commercial airline is able to create a metric using the seven principles listed herein. Lastly, if the Metric for Recognition of Unusuality is successful, it can be used to adjust local operational procedures to avoid the impact of the negative stressors on flight operations and prevent a mishap from occurring due to the overwhelming of the flight crew.



Captain David Williams

Captain David Williams preparing a safety brief

CV: Captain David Williams served as an FAA designated check airman at a regional airline and as a line and training captain. He served as an aircraft mishap board member and as a pilot association safety representative. A US Navy career veteran from the maritime and antisubmarine patrol community, he served in numerous capacities in training, flight instruction and standards, including as a fleet pilot evaluator and check airman. Now retired from flight operations, Captain Williams remains active in safety and training issues. His goals have always been to train to the particular characteristics of each individual so that the pilot group as a whole is standardized and competent. He holds a degree in engineering and does consulting work in emergency response planning.

Captain Paul Miller is an international captain retired from a major global commercial airline. In pursuing the goal of flight operations with zero mishaps, he has served on the pilot association safety committee and on the joint safety forum of the association and the airline. He helped to compose the first rough draft of the FAA Advisory Circular on the joint FAA, airline and pilot association Aviation Safety Action Partnership (ASAP). He served as a safety program manager previously in the US Navy managing safety at two major air installations and a carrier based passenger and logistics squadron. He served on the European Advisory Committee, Flight Safety Foundation. He has presented papers on safety program management, safety forecasting, safety planning and response-based safety programs. He holds a degree in engineering from Rensselaer Polytechnic Institute, a minor degree in Humanities from Saint Leo University and has studied business administration at The College of William and Mary.






End Notes:


[2] KPLR 11 (TV), St Louis, aired, “Amtrak Train thought to be…”, posted May 15, 2015 by CNN Wires,

[3] ibid

[4] Williams, Miller Study of Commercial Mishaps, 2015, published online at

[5] Miller and Williams Predictive Mishap Recognition Using Unusuality Study, 2015, published online at

[6] ibid

[7] ibid

[8] False Color, April 2000, published online at



[11] Williams and Miller compilation of various AAR’s

[12] Fatigue Study showing mental alertness related to rest.,

[13] Swiss Air 111 AAR,


[15], poem by Robert Burns, 1785

[16] Crisis management: The Anatomy of an NTSB Investigation. A Guide for Parties to the Investigation and their Lawyers, April 2013, David Tochen, NTSB, Thomas Tobin, Wilson&Elser, New York.

[17] ibid

[18] FSF Proceedings, IASS 2014, Washington, DC.

[19] Statistical Summary of Commercial Jet Airplane Accidents 1959-2013, Seattle Washington, August 2014

[20] David Learmont, Flight International, Year in Review, EASS 2010, Lisbon,

[21] FAR Part 121 Flight Training Curriculum Segments:,Vol.3,Ch19,Sec6


[23] US Airways Flight 1549 NTSB/AAR-10/03 PB2010-910403 adopted May 4, 2010

[24] ibid, page 3

[25] “What is the Relationship Between Training and Safety in Commercial Air Operations?”, Miller and Williams, Flight Safety Foundation EASS Proceedings, Washington, DC, March 2010

[26] NASA Ames Research Center Fatigue Countermeasures Program,

[27] Wayne Rosenkranz, FSF, AeroSafetyWorld,

[28] NTSB Report: American Eagle Flight 4184

[29] AF447 AAR, BEA, July 2012


[31] Williams and Miller Study, 2015, published at

[32] NTSB Report, USAir 1549, published 2010.

[33] NTSB Report, United 232, 1998

[34] Ethiopian Airlines B767(ET-AIZ) Aircraft Accident in the Federal Islamic Republic of the Comoros, in the Indian Ocean on November 23, 1996″   Ethiopian Civil Aviation Authority. 4 May 1998.



[37] Aircraft Accident Report ASC-AAR-02-04-001: Crashed on a partially closed runway during takeoff Singapore Airlines Flight 006 Boeing 747-400, 9V-SPK CKS Airport, Taoyuan, Taiwan 31 October 2000,” Aviation Safety Council, Taiwan, Republic of China











[48] ibid







[55] ibid