Airbus Incident

[jackellis]

If you're afraid of flying, stop reading. I take no responsibility for making you even more fearful.

There's good news and bad news in this story. The good news is how tough large airplanes really are, which is a testament to the engineers who designed it. The bad news - corporate stupidity (RR, Quantas and Airbus in this particular case), and the perils of automation.

http://blogs.crikey.com.au/planetalk...near-disaster/

[LCHIEN]

the first reports I saw made it sound like just the engine failed altho there was uncontained failure. They landed the plane without incident.

The reports I read in the last couple of days indicated that there was major damage to control systems and things were a lot more dicey than initially reported. apaprently there were two extra captains in the cockpit for evaluations and between the three captains, and two other officers it took them 50 minutes just to read through the error messages and warnings received from the computers.

[gerti]

Between the first photos showing serious damage to the wing and Quantas grounding their 380s immediately, I figured this was likely much more serious than they let on at first.

Looks to me though as if the responsibility rests squarely with RR. Quantas was in the dark, and Airbus built a plane that did survive 3 high energy impacts, each of which damaged structural components and/or took out control systems. The plane stayed on autopilot until final approach.

The incident highlights the principal problem with large planes though: if something goes wrong, it'll affect a lot of people.

[leehljp]

I imagine that Quantas got wind of something REAL fast. The speed at which they placed the blame on RR was what amazed me. Usually with accidents, 24 to 48 hours at minimum go by before even a speculation of blame starts.

The article said that RR was aware of the problem and was moving at their own pace at fixing the problem. That is not good for RR. AND the fact that all maintenance is squarely on RR.

Those are scary picts.

[LCHIEN]

Here's how hairy the flight got to be:

http://www.nationalpost.com/opinion/...643/story.html

[jackellis]

There were two other problems that weren't mentioned in the National Post article. Each wing has two long beams inside wing called spars. Each wing support half the weight of the aircraft. Apparently the front spar on the left wing was damaged, though it isn't clear how badly. A few solid jolts of turbulence might have caused the spar to fail. The wings are very tough and they're designed with multiple load paths so that minor damage doesn't lead to a catastrophic failure, but in this case there's some speculation that damage caused by the engine failure was pretty severe.

In addition to being unable to calculate landing speed (it depends on weight and a number of other factors), flap damage on one side meant flaps could not be used at all, because having flaps deployed on one side and not the other makes the aircraft difficult to control. Flaps help reduce the required landing speed but since they weren't available and neither was the a reliable estimate from the airplane's computer system, the pilots probably used a final approach speed that was on the high side.

A number of professional pilots contribute to a general aviation forum I belong to, and almost without exception they do not like the level of automation Airbus engineers have built into their airplanes. The National Post article suggests why they feel the way they do.

[LCHIEN]

the fault trees in the computer can't possibly anticipate all combinations of faults when there are more than a few; it also can't anticipate failure of backup systems (it tends to assume they'll work - that the backup data busses that should have taken over).

There is no good answer when the system has too many problems and the computer suggestions go haywire - you should just shut down and figure out what you really have but for flight systems that isn't an option.

MAYBE WE SHOULD ALL BE FLYING in TWO-HUNDRED PIPER CUBS INSTEAD OF ONE BIG a380.

[gerti]

I read somewhere that the flaps did work and were used, it was the slats that were jammed in the retracted position. And the reason they stopped 100m from the end of the runway is because that was where the most fire trucks were waiting.

But it was certainly an extremely dire situation, and the pilots saved a lot of lives that day.

[lrogers]

My take on all this is that it was the "computer" located between the ears of the flight crew that brought about the happy ending to this mess.
Certainly not a good day for RR.