Posted on 06/27/2009 5:07:40 AM PDT by Erik Latranyi
A Northwest Airlines jet traveling from Hong Kong to Tokyo last Tuesday suffered a series of equipment and computer malfunctions strikingly similar to those encountered by Air France Flight 447 just before it crashed into the Atlantic Ocean on May 31.
The Northwest plane and its passengers, however, emerged unscathed. Details of the harrowing incident – described in a memo by one of the Northwest pilots and confirmed Friday by others familiar with the matter – highlight how cockpit crews can safely cope with something that is almost never supposed to happen: a system breakdown that prevented the crew from knowing how fast the plane was flying.
During the brief but dramatic event, the Northwest Airbus A330's crew was left without reliable speed measurements for three minutes. In addition, the computer safeguards designed to keep the aircraft from flying dangerously too fast or too slow were also impaired. Like the Air France A330 jetliner, the Northwest plane entered a storm and quickly started showing erroneous and unreliable airspeed readings.
(Excerpt) Read more at online.wsj.com ...
That's because, most of the time, GPS is nowhere near as accurate in the vertical. If the display was the same resolution, it's would change all the time, each update, even driving down a nice flat road, or sitting in the parking lot for that matter. This is due to something called "geometrical dilution of precision". It affects all the position components, but it take a really bad/unusual set of satellite geometries to make it bad in the horizontal, but it's not at all rare to have the visible satellites mostly out near the horizon, which means they are nearly in the same plane as your local horizontal plane. Which means the measurements are relatively bad normal to that plane, IOW in the up/down direction.
How about both, a minimum amount of good training. Sure there's always the temptation to just make the minimums, and do it in the easiest way possible. But surely training with good scenarios, focusing on the most important and/or hardest to master items shouldn't cost any more than poor training. You tie up the sims the same amount of time in either case. I'd guess maybe preparing the scenarios and "lesson plans", would take a bit more effort than just cranking out hours of lessons.
It just never occurred to me that TIME in the simulator wouldn't be put to the best possible use, FAA time mandates or not.
I thought it was because it would be tough to fly straight and level in an aircraft designed for maneuvering, and as such, highly responsive to control input. Please correct me if I am wrong.
Seems I recollect reading somewhere that early biplanes which were good at dogfighting were also not pilot-friendly because of inherent narrow windows of attitude stability which made them more maneuverable.
Now, that’s about as rational an explanation of the “Z-problem” as I’ve seen! Thank you!!
The results are the proof. Human-factors training and a dynamic ISD are more effective than time mandates, and airlines have the data to PROVE it. Every airline that has abandoned the time approach has actually improved their training, and in many cases increased the time, but not by mandate, but because THEIR data supported it. Some parts of the FAA actually think the airlines train only for the least expensive option. This laughable considering the ENORMOUS sums spent every year in training. The major airlines are more safety minded than many in the FAA.
You're welcome. Although I didn't think the explanation was all that good.
I'm an engineer, I need to be able to scribble on a white board (actually I'm old enough that I did much scribbling on chalk boards), or at least wave my hands around, to do a really decent job of explaining something. :)
It's actually not so much the ability to manuever, that is pull g's, but rather the ability to do so quickly. Most aircraft are dynamically stable. If you let go of the controls, they will settle into a steady attitude, perhaps climbing or diving, but not chaning attidue and direction of flight. Aircraft like the F-16 and F-22 are dynamicaly unstable, or marginally stable. It's takes an active control, a feedback loop, to keep them at a constant attitude. Unlike the stable aircraft, absent their computerized flight control system, they would diverge after any little disturbance. Further more, they would do so to fast for pilots to correct them, unlike those biplanes which were probably marginally stable, but with the "time constant" of the divergence/instability long enough that a pilot could easily provide the necessary feedback.
The first aircraft, the Wright Flier, was unstable, due to having it's elevator in front of the wings, rather than behind. You can actually see that in some old motion pictures of them. You can of see it in this video of a reproduction Wright B model. It's not as obvious as with the "A" model, but you can see it in the flapping elevator, especially right after takeoff.
From what I gathered on Airliners.net, there have been 35 previous incidents with the A330.
You seem to be knowledgeable and trustworthy.
Are you in "industry rep mode and citing the party line" -- or, do you really, deep down inside, believe that?
The aircraft was out of range of "man portable" anti-aircraft weapons. Only the US Navy was in position to shoot that aircraft down, and I don't believe that's possible for a second.
I wanted a straight answer from someone who flies them; that is why I asked safisoft.
I watched a television show, Discovery or something, that went though this in detail, temperature, combustion, ... and they argued/demonstrated it was possible.
The center tank had to be near empty (it was) and hot (it was, summer, and located above the air conditioning units) for the explosion to occur.
I didn't do the analysis and its not my area, so I can't say it was correct.
Since the CWT explanation was brought forward, I (a physical chemist) have wondered if that batch of fuel might have been contaminated with a more volatile fraction.
If one wished to be conspiracy-minded, one might wonder if only the contents of that specific CWT might have been so contaminated...
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I'm glad you have confidence in the official explanation.
Thank you again for a straight answer!
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