Miles O'Brien

Reporting on space, science, aviation & tech.

Tag Archive: Paris-Charles de Gaulle Airport

  1. A Dark, Stormy Night over the Atlantic

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    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.”

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    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.

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    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?