Saturday, December 10, 2011

The Conversations of Doomed Men

I read this last night, and have found myself strangely moved and preoccupied with it ever since.

Popular Mechanics has a transcription of the black-box record aboard Air France Flight 447, the plane which crashed into the Atlantic Ocean on June 1st, 2009, killing everyone on board.

What's very interesting is that they recount the conversation between the two co-pilots who were flying at the time, and intersperse it with descriptions of what was actually going on with the plane as the discussion took place.

Let me quote the part of the article that is most puzzling:
The Airbus's stall alarm is designed to be impossible to ignore. Yet for the duration of the flight, none of the pilots will mention it, or acknowledge the possibility that the plane has indeed stalled—even though the word "Stall!" will blare through the cockpit 75 times. Throughout, Bonin will keep pulling back on the stick, the exact opposite of what he must do to recover from the stall.
I quote that much merely to encourage you to read it all- if I quote more, I am going to do injustice to just how strange it is to read the whole transcription. So you should definitely read the whole thing. And when you're done (and only then), come back and read the rest of my thoughts below the jump:

The central dynamic in this, as far as I can tell, was that the junior co-pilot had started to panic and did exactly the wrong thing, while the senior co-pilot knew what the problem with the plane was, but didn't know (or think to ask) that it was being caused by the junior co-pilot, and this stopped him from knowing how to fix it.

So why did they get misled? How did the senior co-pilot and the captain not look around and figure out what was happening?

My best guess comes from the following. When I read the dialogue, the part that was most strange to me was that even as the narrator describes the horrible decisions being made, the words of the co-pilots still seem vaguely reassuring. As a reader, they still sound highly trained and fairly calm in trying to figure out the situation (the transcription doesn't convey tone, so I might be wrong about how it would have sounded in real life, but the words themselves gave me this feeling). They sound like people I'd want to have in the cockpit. But in this situation, they weren't. They were fatally screwing it up and crashing the plane when there wasn't a major mechanical fault.

And this is part of the problem - when you're panicking yourself, it's very easy to be reassured by someone else's discussion of the problem. This holds true even when what they're doing is going to kill you in sixty seconds time. As a reader, I know with certainty how this ends, and I don't have the full-on pit-of-my-stomach monkey brain fear of being in the cockpit at the time. And yet I still had a sense of reassurance from reading their words. Imagine how much stronger this feeling would be as the other co-pilot, when you don't know what's going on, and you have even more reason to trust the judgment of the person next to you whom you know well.

Secondly, pay attention to just how many things go wrong in sequence, and how many times there were when either a change in some random event or a different decision by one of the pilots might have averted the crash.  A whole lot of things have to go wrong for one of these planes to drop out of the sky. I guess this is good news, but it doesn't make this scenario any more fun to read.

Thirdly, note how the plane's automatic systems for improving safety in normal times seem to make things significantly worse in abnormal times. The most pernicious of these seems to be the one where the plane stopped making the stall alarm because it thought the data inputs it was receiving were obviously junk. Am I crazy, or is this a horrible algorithm to have??? Normally, when instruments are giving junk readings, pilots have the task of trying to work out themselves if the readings make sense or not. But now, they've got an extra layer of complication - once things start going wrong, they have to also try to second guess whether the problem is fixed, or the problem has gotten so bad that the computer has decided that the readings are junk and it's no longer reporting a problem. Which led to the horrendous result that steering the plane down, which was improving the situation, triggered the stall alarm because it sent the readings from 'so bad we're ignoring them' to 'bad but realistic'. Yeesh. This is in addition to the switching to 'alternate law', i.e. it's now possible for you to crash the plane, even though most of your training is in a setup where it's not possible to crash the plane. It's not clear from the article how much this change was signalled to the pilots at the time, but it seems like something that you really want to blare out.

Update: Lots of interesting discussion at Hacker News, particularly emphasizing the apparent lunacy of averaging the two pilots inputs - hmm, one guy wants to go up, the other wants to go down, let's just take the average. Why on earth would you ever want to do that?
End Update.

But perhaps what is most haunting about the whole article is the eerie sense of foreboding, catharsis and voyeurism that comes from observing the discussion and actions of these men in the final minutes of their lives. Every word, every action, had incredibly high stakes, for them and the 225 other people on the plane. And they screwed it up. It's a morality play in a universe where your moral failings bear little proportion to the outcome, and there are no second chances. For about two minutes of your life, you panicked and didn't think clearly. Bam, you're dead.

And the hallmark sign that you're reading a real death scene, and not a Hollywood script, is the sheer confusion of the situation. Until the last 48 seconds of the flight (when the junior co-pilot said that he'd been pulling back on the stick), nobody on that plane knew what the hell was going on. The tragedy is compounded by the fact that the senior co-pilot and pilot found out, after it was too late, what the problem had been. And even then, confusion reigned.

The last words of co-pilot David Robert, 1.4 seconds before he died, were these:
Putain, on va taper... C'est pas vrai
(Damn it, we're going to crash... This can't be happening!)
But it can. And one day it will.
Quod per sortem
sternit fortem,
mecum omnes plangite!
(And since by fate,
The strong are overthrown
Weep Ye All, With Me!)
(Carmina Burana)

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