Archive for June, 2009

Some Stories are too Good to Check Out…

June 19, 2009

I wish I had a T-shirt like this (yes, that is a hint).

CAPE CANAVERAL, Fla. — WESH 2 News struck a nerve with an exclusive report as NASA actively works to prevent shuttle sabotage from within its ranks.

While there is no indication that sabotage has ever or will ever happen, officials said it is on the space agency’s radar as the shuttle program winds down.

While the deputy manager of the space shuttle program has said publicly that NASA has had many discussions about the possibility of intentional damage to the shuttle, officials emphasized on Thursday that there is no evidence it has happened.

via NASA: Sabotage Possibility Investigated For Years – Space News Story – WESH Orlando.

It’s getting pretty ugly out there, Space Cadet Nation.

We all know every reporter worth his notebook wants to score a scoop – a big “exclusive” that will make him a newsroom hero – but sometimes the pressure to produce will lead a good scribe down a dark alley.

This item from WESH-TV in Orlando is a good example of how a rumor mixed with a hunch leads to some pointed, loaded questions, which in turn prompts some unclear, easily-misconstrued answers.  Voila – an Action News Sensation! Too bad it is not “sweeps” month…

But sometimes the facts get in the way of a good story. I suppose the “exclusive” has a little truthiness to it: a program in its autumn years, thousands of jobs about to disappear…surely the workers are desperate to do anything to keep the paychecks coming. Surely.


Site of the Hydrogen Leak that has caused three shuttle scrubs.

But I am not talking about the workers who make the shuttle fly (men and women who proudly call themselves “Pad Rats”) – I am referring to the local TV reporters who are facing the imminent demise of their business. Might they be tempted to engage in a little sabotage of the truth to keep their jobs? Perhaps we should ask their managers about this?

Here is what I know to be a fact: The Pad Rats – and all the other shuttle workers at the Kennedy Space Center –  are the most committed, conscientious, diligent people on the planet. They take their risky business very personally – and are constantly focused on the safety of the men and women who strap themselves to the rockets they prepare for launch. It is inconceivable to me that they would do anything that would put them – or their fellow workers – in (greater) harm’s way.

And then there are a few practical things to consider:

First, the shuttle is set to retire at the end of 2010 – no matter how many flights are in the history books. Even if workers were adding delays by busting valves, crossing wires or siccing a woodpecker on the fuel tank foam, they would not be changing the date of that last paycheck one iota.

And no one does anything at or near a space shuttle alone. Ever. It takes a village to tighten a bolt on a booster. Every step is considered and approved by a safety guy. The work is watched by a quality control expert to insure it is done to spec. And the customer is present as well: a NASA civil servant is there to add his/her imprimatur and “buy the paper” documenting the work (remember, the wrench-turners who work on the shuttle are employed by the United Space Alliance and its subcontractors).


Astronaut Susan Still shaking some "Pad Rat" hands after landing in 1997.

And finally, there are the people actually doing the work. They also don’t do much of anything alone. So it is quite a gaggle at the site of every piece of important work aimed at getting a shuttle ready to fly. Might there be an unhappy camper in the bunch? No doubt. These days the mood is pretty sour in the Space Cadet Nation – especially in the Province of Shuttledom. It is never fun when the party is over. But any sabotage campaign would require a fairly large conspiracy by some people who are not wired to think that way at all.

Of course reporters are wired just the opposite way.

The Paradox of 'Simplicity'

June 10, 2009

Boeing 707

Air France Flight 447 went down in a giant, dangerous, violent storm that might not have been survivable under any circumstances. But as the Airbus A-330 penetrated that huge system of thunderstorms, sensors, systems and computers on the plane started failing in a rapid cascade that would make any pilot’s head spin – even if he was not in the middle of extreme turbulence flying blind in the night.

The failures likely sealed the fate of the 228 souls sealed inside that thin metal tube as it hurtled through the dark, stormy night – but were they contributing causes with their own roots – or simply the unavoidable outcomes of a decision to fly such a perilous course?

Airbus A-330

Airbus A-330

Remember, more often than not, an airliner goes down at the end of long chain of unrelated, seemingly innocuous decisions, malfunctions, mistakes and external factors. Remove any single link (or even change their sequence) and you have an on-time arrival at Charles de Gaulle. So how do those system failures fit in the chain of calamity?

Consider for as moment these two cockpits. On the left is the granddaddy of jet airliners – the Boeing 707 – which first flew paying passengers in 1958. On the right is the Airbus A-330 – which started flying the line 35 years later. Now quick: which is the more complex airplane? Looks can be deceiving.

Relatively speaking, the 707 is a much simpler airplane – which is different from saying it is simpler to fly. Mastering and monitoring all those steam gauges required an alert three-person crew. In the 707, the burden of the complexity – and the opportunity for error – is on the human side of the instrument panel. Because humans make mistakes and machines do not, airplane designers have steadily shifted that workload to the other side of the gauges over the years. The A-330 instrument panel is proof they have done a bang up job. It looks simple to fly doesn’t it? It is.

The joke is that in the not too distant future, flight crews will consist of one human pilot and an ill-tempered junkyard dog. The pilot is there to watch the computers fly the airplane – and the dog there to bite him if he tries to touch the controls.



Airbus has embraced the philosophy (if not the joke) with zeal. The company builds highly automated “Fly-By-Wire” airplanes. NASA developed the first fly by wire aircraft in 1972 – an F-8C Crusader. On FBW planes, the movable surfaces on the wings, the horizontal and vertical stabilizer are not connected to the controls on the flight deck with cables, pulleys pushrods and hydraulic actuators as they were on the 707.

Instead, electrical wires transmit the pilot’s commands to hydraulic actuators that move the aero surfaces. Between the pilot and those surfaces is a bank of computers that are actually flying the plane. The computers are programmed with some strict rules (in fact, Airbus calls them “Laws”) designed to assess the human commands from the flight deck – and veto them if they would put the plane in harm’s way. Point the nose too high or too low – or bank to steeply and the computer will correct your bad airmanship. Who’s in charge here?

Pilots like to call their autopilots “George” (old phonetic shorthand for “gyro”, which makes the AP work) – on an FBW airplane, “HAL” might be more apt.

HAL 9000

HAL 9000

Dave Bowman: Open the pod bay doors, HAL.

HAL: I’m sorry Dave, I’m afraid I can’t do that.

Dave Bowman: What’s the problem?

HAL: This mission is too important for me to allow you to jeopardize it.

-From 2001: A Space Odyssey

But what happens when the silicon co-pilot gives up the ghost? It gets very ugly – very quickly. Just before Air France 447 went down, it transmitted a four-minute spurt of text data reporting 5 failures and 19 warnings via its Aircraft Communications Addressing and Reporting System (ACARS). The data is cryptic and we will only know the full scenario if searchers find the black boxes, but we know the autopilot disengaged, the flight control computer failed, warning flags appeared over the primary flight data screens used by the captain and first officer and the rudder moved beyond its limits.

A-330 Pitot Tubes

A-330 Pitot Tubes

All of it is consistent with a flight control system that was getting some bad information about how fast the airplane was moving through the air. The device that performs this task is called a pitot tube. Pointed in the direction of flight, it measures the relative pressure of air as it flows in. For pilots this is a crucial device – (like an EKG for a heart surgeon, I suppose).

If you don’t know your airspeed, you can easily stall or overspeed the plane. That’s why the A-330 has three pitot tubes. They tend to be ice collectors on an airplane flying through precipitation. If they glaze over, or get clogged with crystals, they won’t work – so that is why they are heated. Even so, A-330 pitot tubes were icing up and failing in flight so Airbus issued a “service bulletin” recommending airlines replace them with a newer model that has a more powerful heater. It was not considered urgent – and so the pitot tubes on the doomed plane had not been removed and replaced. But I would not focus on this too much.

The epic thunderstorm system that Air France 447 flew into would have been a huge hail and af-447-storm-clouds1ice-generating machine that could have overwhelmed even the new and improved pitot tubes if they had been installed.

Regardless, the failure cascade chronicled in the ACARS text message hauntingly matches a 2008 event when an Air Caraibes A-330 flying the same route encountered some serious pitot tube icing. That plane was not in such severe circumstances so the crew was able to get things back under control – and lived to tell the tale.

Now here is a key point to remember: as systems fail in an Airbus, the laws that the computers live by change from “normal”, to “alternate”, to “abnormal alternate” to “direct”.  At each stage the computers surrender more authority to the humans – until finally silicon surrenders and the carbon pilots are on their own – with no help at all from HAL – at just the point they need him most.

They were in the dark, getting hammered by turbulence, flying blind, by hand, a plane that was designed and built to be controlled by machines – with human supervision.

Suddenly that deceptively simple cockpit was a riddle so complex it could not be solved.

The 'Coffin Corner' and a 'Mesoscale' Maw

June 8, 2009

The A330 that crashed a week ago - from

The Air France 447 mystery may never be solved beyond a shadow of doubt, but there are some telling, tragic clues to consider based on what we know about the airplane systems and the extreme weather and aerodynamic conditions it encountered before it went down a week ago.

First, a bit of aerodynamics: The doomed Airbus A-330-200 was flying ever so close to its maximum altitude – in a zone pilots call the “Coffin Corner”. It refers to the edge of so-called “flight envelope” of an aircraft. At this altitude, the air is much thinner and that significantly narrows the swath of speed at which the airplane can safely operate.

Because there are relatively few air molecules passing over the wings, they need to be moving faster to generate enough lift to keep the plane at altitude. They will stop flying (stall) at a much higher speed (true airspeed) than they would on approach to an airport at sea level.

At the other end of the safe speed spectrum is the sound barrier. The wings on an airliner like the A-330 are not designed to break the speed of sound. Venture toward Chuck Yeager country and an airliner will begin buffeting. And as altitude increases, the buffet speed (the sound barrier) decreases (once again the dearth of air molecules is to blame).

So you see the squeeze play as a plane flies toward the Coffin Corner: the margin between the between the high and low speed limits gets thinner and thinner (along with the air).
Matter of fact, given its estimated weight, altitude and the outside air temperature (which also affects air density), AF 447 was flying through the eye of a speed needle only about 25 knots (28 mph) wide.

And one more important point: as jet engines fly higher, they steadily lose their oomph (you know, thin air). Matter of fact, the maximum altitude a plane can safely fly is partially determined by the point where the engines can no longer maintain a minimum rate of climb. In other words, you are supposed to level off just before they go into “Scottie” mode (“No more power, Captain!”).

So while you are napping, eating or watching a movie on that flight to LAX, you should know the plane you are flying is cruising along at the ratty edge of its capabilities. Why? Money. The higher an airliner flies, the better gas mileage it gets.

But rest easy, white-knucklers; flying in the “Corner” is routine and safe – so long as the weather is benign, the air is smooth and the sensors, avionics, computers and autopilot are all doing their job.

But of course that was not the case for Air France 447.

The weather where and when the plane went down was horrible – the storms among the meanest weapons in Mother Nature’s arsenal. On their nose, the crew would no doubt have seen the outline of a towering wall of cumulonimbus clouds – illuminated in strobe-light fashion by lightning.

Seeing this would not have been a big surprise to them. Their pre-flight weather briefing would have included satellite imagery clearly depicting the “Cb’s” – as pilots call them. Besides, big storms are a common occurrence over the Atlantic along the equator – where the airflows of two hemispheres collide.


Satellite Image of MCS that Air France 447 flew into - From Tim Vasquez

Meteorologists call the storm AF 447 flew into a “Mesoscale Convective System” – a large complex of multiple thunderstorms where the sum total is greater than the individual parts. MCS storms are obviously much bigger than your garden-variety thunder-bumper – and they last a lot longer. [More about the weather at Tim Vasquez’ insightful, detailed blog.]

Precisely because big thunderstorms are common there, airliners are constantly threading their way through the nastiest cells – deviating at the pilot’s discretion. But no professional pilot would knowingly auger into the heart of a thunderstorm this potent. A pro knows no airliner is designed to survive those conditions – no matter how advanced it is technologically and structurally.

Hard to believe in this day and age, but when you are flying over the pond, you are pretty much on your own. You are not talking to air traffic controllers or being painted by their radar – and of course there are no weather reporting stations beneath you. By definition, thunderstorms are unstable, dynamic and fast-moving. So by the time they reached the storms – more than four hours into the flight – what they learned in the pre-flight briefing was yesterday’s news.


Weather Radar - from NASA

As a result, flight crews rely heavily on the weather radar bolted onto the nose of the airplane. It is a very useful safety device but interpreting its display is a bit of a black art. A lot of pilots, frankly, do not fully understand the intricacies of its capabilities and limitations. It is akin to a blind man with a cane; he can tell something is in his way, but he doesn’t see it.

For instance, the radar mostly detects rain and hail – and if that first layer of storm cells was particularly heavy, it might have acted like a curtain – hiding the reinforcements from radar beams. With the benefit of hindsight (and satellite imagery captured at the time of the crash), we know now there were at four more layers of strong storms behind the first line of cells. And radar cannot detect the strong updrafts of warm air that feed a thunderstorm.


Infrared image of storm - from Tim Vasquez

Did the Air France crew spot a gap in that first line of storms that turned out to be a “sucker hole” – sending them into a box canyon of violent storm cells? Maybe. If they could have seen the full depth and intensity of those storms, would they have changed course to avoid it? Hard to imagine they would say, “Steady as she goes…”

No matter how they made their decision to fly into the maw, it was likely not long before they would have known they made a big mistake.

The last message from the crew – a text – indicated they were flying through thunderstorms with “fortes turbulences” (strong turbulence). Hard to know exactly what he meant. In the US, we define turbulence as “Light”, “Moderate”, “Severe” or “Extreme”.  The FAA defines the latter as “turbulence in which the aircraft is violently tossed about and is practically impossible to control. It may cause structural damage.”

Extreme turbulence is precisely what an airplane would be apt to encounter inside an MCS.

Flight Profile created by Tim Vasquez

Flight Profile created by Tim Vasquez

So why wouldn’t they just make a speedy U-turn at that point? They might have, but attempting a maneuver like that in severe or extreme turbulence would likely have made things worse. Remember, the engines were close to maxed out and the speed margin was minuscule before the plane pierced the storm clouds. Simply banking the wings could be enough to trigger an aerodynamic stall.

And consider this: those updrafts bring warm moist air to higher altitudes – feeding the storm. That also might have increased the air temperature where the Airbus was flying. Warmer air is less dense – with fewer molecules – meaning the airliner might have suddenly been flying above its maximum safe altitude.

Bottom line: if all sensors and systems on the Airbus kept working the aircraft might have been hard pressed to stay aloft. But of course, the systems started crashing before the airplane did.

So were those failures contributing causes of the crash – or simply the upshot of an aircraft taking a beating it could not withstand? Maybe it is a little bit of both.

More on that tomorrow…

Long Odds Search for Black Boxes

June 3, 2009

They aren't "black". FDR - from NTSB

Now that searchers have found some floating remnants of Air France 447 in the Atlantic 430 miles (700 kilometers) north of the Fernando de Noronha islands, the hard work of trying to locate the Airbus’ “black boxes” – the Flight Data Recorder and Cockpit Voice Recorder – can begin. This is actually much worse than the proverbial needle in the haystack, because in that case, the assumption is the needle can be found after expending a lot of time and energy. These boxes might very well be truly lost to the abyss.

But of course they still must try to find them as well as any wreckage of the Airbus A-330.

CVR - from NTSB

CVR - from NTSB

To that end, a French research ship with a submersible capable of diving to a depth of 20,000 feet (6,000 meters) is steaming to the area.  The French transport Ministry says the ship carries equipment “able to explore more than 97% of the ocean bed area, specifically in the search area.” I some spots,  Atlantic is more than 20,000 feet deep in the area where searchers found the floating debris.

The submersible will be listening for the distinctive “pinging” noise that these boxes are designed to emit once they are submerged in water. They are supposed to “ping” for thirty days in water as deep as 20,000 feet. In ideal circumstances, the pings can be heard no farther than 5,000 feet away  – so it is essential to send some “ears” deep beneath the sea in order to find the boxes. These sonar devices can be towed by ships or ply the deep on their own power.

The technique has paid off in the past. In 2007, the USNS Mary Sears used a towed underwater sonar to to locate the black boxes that were on board an Indonesian airliner that crashed on a domestic flight on January 1, 2007. The boxes for Adam Air Flight 574 – a Boeing 737 – were found at depths greater than 6,000 feet (1,800 meters).

But where, precisely should they search for AF447? Simply looking where the floating debris was found is not wise – as ocean currents and wind have likely moved those items away from the wreckage that lies beneath.

Remember, this aircraft was beyond radar coverage at the time it crashed, so finding a place to begin a search requires a little bit of sleuthing. That is precisely what meteorologist and blogger Tim Vasquez has done brilliantly here. If he is right, the wreckage would lie somewhere between 10,000 and 13,000 feet beneath the surface. Maybe that is within reach. Maybe.

af447-weatherBeing a weather guy, Vasquez has taken his position hunch and mashed it up with the meteorological data at that time/place.  The results will make your blood run cold. AF447 flew into the maw of an extremely powerful line of embedded thunderstorms that rose to at least 51,000 feet.

“The aircraft was certainly within the bulk of an extensive cumulonimbus cloud field for a significant amount of time,” writes Vasquez.  “(The) storms could indeed have been a contributing factor to the crash.”

Remember, as I said in my previous post on this, it is seldom one single cause that brings down a modern airliner. But you have to wonder why the crew did not deviate from this extremely hazardous course.

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June 1, 2009

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A Dark, Stormy Night over the Atlantic

June 1, 2009

Photo of F-GZCP - the airliner that crashed - from JetPhotos.Net

So what happened to Air France Flight 447? It is early and speculation at this juncture is often wildly wrong. And remember, there are usually several factors that conspire to bring an airliner down. But here is what we do know for sure. Keep this in mind as you process the often inaccurate reporting on aviation that is so prevalent in the mainstream media.

The Timeline – The flight, carrying 216 passengers and 12 crewmembers, left Rio de Janeiro at 2203 GMT (7:03 PM local time). It flew beyond radar coverage 3 hours and 33 minutes later (at 0133 GMT). A half hour later (0200 GMT) – now four hours into the flight – the plane encountered heavy turbulence. Fifteen minutes later (0215 GMT), now a long way out to sea, it transmitted automated signals indicating the plane was in serious trouble.

“A succession of a dozen technical messages (showed that) several electrical systems had broken down,” according to Air France CEO Pierre-Henry Gourgeon. He described the failures, which included (most ominously) the pressurization system as “totally unprecedented situation in the plane.”


Weather over Atlantic during crash - From Naval Research Lab

It was a dark and stormy night – in a place that is home to the world’s worst thunderstorms. Just as it disappeared, the Airbus A330-203 was flying into a thick band of convective activity that rose to 41,000 feet. This equatorial region is known as the Intertropical Convergence Zone – it is where Northeast and Southeast Trade Winds meet – forcing a lot of warm, moist air upward – which condenses – an efficient thunderstorm producing machine.

The crew had “Sully-esque” seasoning – The Captain had 11,000 hours total time (1700 in the Airbus A330/A340). One Copilot had 3,000 hours total time (800 in the Airbus A330/340) and the other Copilot had 6,600 hours total time (2,600 in the Airbus A330/340).

The Airbus A330 has a good record – and this was the first crash of a twin-engine A330 in revenue service in its history. In 1994, seven employees of Airbus died when a 330 went down during a test flight. The accident report says it was a case of pilot error. The airplane that crashed last night – tail number F-GZCP – had no accidents or incidents in its history. It went into service on April 18, 2005 and had logged 18,870 hours. In 2006, it’s wing collided with the tail of an Airbus A321 on the ground at Charles de Gaulle Airport – the damage was classified as “minor”. It was last in the hangar on April 16, 2009l for routine maintenance. No serious squawks reported.

No reason to believe terrorism – While you cannot take the possibility of a bomb off the list just yet, no groups have claimed any responsibility for downing the plane. What good is a terrorist attack if the perpetrators don’t, well, terrorize us?

So consider this as a possible scenario: The crew is flying toward a line of storms in the dark, out of range of land-based radar. They are equipped with on board weather radar however – and can use it to thread their way through the bad cells if need be.

It is quite likely the airplane was struck by lightning – or it could have triggered lightning by the mere act of flying at Mach .8 through storm clouds. It is not impossible that could have sparked a fuel fire – but that is highly unlikely. In fact, it has been four decades  since lightning alone caused an airliner crash in the US. A lot of time and effort is spent protecting airplanes from this clear and present danger (interesting piece here). And airliners get hit by lightning all the time – you don’t hear about it because nothing bad happens. Remember, it is seldom just one thing that brings a modern airliner down.

Many of those airliners that get hit by lightning are so called fly-by-wire aircraft (meaning the controls in the cockpit are linked to the movable surfaces on the airplane by electrical wires and computers). Airbus pioneered FBW control systems in commercial airliners and the engineers in Toulouse have gone out of their way to demonstrate their products are safe in stormy weather. There are four fully redundant electrical systems on an Airbus – and if the worst happens, a manual flight control system that allows the crew to fly the plane (barely) using the rudder, differential thrust on the engines and horizontal stabilizer trim. [You may recall that is how the crew of United flight 232 managed to get a DC-10 on the ground in Sioux City, Iowa in 1989 after a complete hydraulics failure]

Ironically, one of the systems most vulnerable to lightning strikes is the on-board weather radar located in the nose cone. It cannot do its job if it is shielded from lightning like the rest of the airplane is – and so it is more likely to go down when bolt strikes (which is, of course, when you need it most). So it is possible this plane was hit by lightning, knocking out the radar.

You can imagine the crew was suddenly preoccupied with multiple electric failures that left them in the dark, over the ocean and without weather radar as they hurtled toward some epic cumulus nimbus thunderheads. This would have been a serious emergency that should prompt a pilot to do a 180 and head for the nearest suitable size slab of concrete.

The fact that the airplane sent automatic warnings that it had an electrical problem means, by definition, that it was not a total, instant failure. But did things cascade from there? They might have found themselves inside a huge storm only able to control the airplane manually – which means minimally – with the rudder primarily.

And then there is the Airbus rudder. You may recall the crash of American Airlines flight 587 on November 12, 2001 as it departed New York’s JFK airport. The plane encountered some wake turbulence and the copilot apparently stepped too hard on the rudder pedals – breaking off the graphite vertical stabilizer and rudder (the tail).

As long as we are talking about pilot inputs leading to broken airplanes, consider this important point: when the Airbus FBW system is up and running as it should, there are all kinds limits placed on the pilot’s ability to move the control surfaces of the airplane. It’s sort of like a governor on a car engine. If you move the controls too far, too fast in any direction, the computer, in essence, ignores the human being’s commands and keeps the plane inside the flight envelope. This is designed to stop a plane from stalling, spinning, gaining too much speed or pulling too many “G’s” because a pilot is over-correcting (which of course, is not correct at all).

But as the electrical systems start failing, the machines lose their authority to trump the humans fairly quickly. Depending on how many multiple failures of redundant systems there are, the so called flight control laws change to “Alternate”, “Abnormal Alternate” and finally “Direct Law”. At each level, the pilots get more authority to move the control surfaces without the machines intervening. So a combination of loosened fly-by-wire reins, cruise speed and extreme turbulence would increase the potential for an in-flight breakup.


AA 587 crash site in Queens - from NOAAEven today’s advanced - seemingly invincible - airliners are no match for Mother Nature on a bad night. If a big airplane ends up in the teeth of a powerful thunderstorm, it could be torn to pieces in an instant.

We do know whatever happened on that airplane in its last few minutes was nothing short of horrifying. It is hard to imagine the kind of turbulence that would break up an airliner. My heart goes out to the passengers and crew.

Will we ever know what happened? This one will be hard. The wreckage will be likely strewn over a wide area – and locating the Flight Data and Cockpit Voice Recorders won’t be easy since they are likely at the bottom of the sea – possibly 24,ooo feet below the surface. Even if they are transmitting their homing signals, you would need a lot of luck and a pretty stout submersible to retrieve them. But that may be moot – as simply knowing where to search will be difficult.

One thing which may help: those automatic messages indicating system failures – which are designed primarily to give mechanics a heads up about problems so they can turn a plane around on the ground faster – no doubt contained much more information than is now in the public realm.

Which brings me to this wild idea: why not send steady streams of telemetry from airliners to the ground all the time – ala the space shuttle? This effectively places the “black boxes”, safe and sound – on the ground. Imagine how invaluable that much data would be right now – given the the distinct possibility this could remain an unsolved mystery.

We all need to know what happened to Air France 447. Is there something that makes the A-330 fleet unsafe in certain conditions? In the absence of real facts, will conspiracy theorists spin a tale of terrorism and government cover ups? Did the flight crew make crucial errors in judgment? Or was this an unavoidable scenario – bad luck with odds so long that nothing or no one is really to blame?