Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

What really happened aboard Air France 447

popularmechanics.com

Post reply on HN
Print view View original

141–150 of 374 posts

Re: What really happened aboard Air France 447

#141

Post by einhverfr »

joshAg wrote: post #133
teyc wrote: post #102

The state of UX design has advanced so much, perhaps we need more UX testing so that even pilots who are unfamiliar with a plane could figure out what to do. Amazon probably does more with figuring how to help users checkout their shopping cart than plane designers helping pilots get a plane out of a stall. Alternate law and normal law introduces two modes. This breaks one of the rules of user experience, especially…

pitot tubes just measure longitudinally forward airspeed (ie the direction the plane is going). altimeters measure asl (above sea level) altitude, and gyros measure angle of attack and accelerations. I believe there is a way to tell stall just from altimeter and gyro readings when combined with state information (flap position, gear up/down, &c.) about the plane. great points about the ui design, though. i think the…

AoA sensors are separate from pitot tubes and in every schematic I have seen located on the exterior of the aircraft, so I believe the measurement is direct.

Re: What really happened aboard Air France 447

#142

Post by StavrosK »

einhverfr wrote: post #128
bambax wrote: post #112

Earlier quoted context omitted.

What's missing from this article is the fact that the Captain chose to fly right into the storm, saying "on va pas se laisser emmerder par des cunimbs" (in essence: "fuck this storm") http://www.lexpress.fr/actualites/2/actualite/des-dialogues-... This is incredible hubris. Then, in the middle of the storm he leaves the two copilots alone, one of them quite inexperienced, and goes for a nap. He's obviously trying to…

IANA Pilot. I do make aerodynamically correct fixed-wing and lifting-body type paper airplanes, however, and I have had a LOT of fun playing with aerodynamics in this hobby. One thing to keep in mind regaring stall is that it's 100% dependent on angle of attack, not speed (something Popular Mechanics gets entirely wrong). What happens basically is that at a high angle of attack the air layer doesn't track the wing su…

Is it possible that the warning speaker was broken? It's odd that none of the pilots would even acknowledge it. Or does the recorder record the stall warning noise too?

Re: What really happened aboard Air France 447

#143

Post by StavrosK »

Klinky wrote: post #30

Co-pilot Robert, after finally getting full control back from Co-pilot Bonin: "Damn it, we're going to crash... This can't be happening!" Co-pilot Bonin, who had been pulling back & stalling the plane during the crisis: "But what's happening?" Pretty much sums it up. I am thinking that perhaps Bonin had shellshock & may not have even realized he was holding the stick back. Perhaps the more experienced Robert didn't t…

What I don't get is why THE HELL are the two sticks averaged? What's the reasoning behind this? "Hey, one pilot thinks we should descend, the other we should climb, better maintain altitude without telling either one about it". Why?

Re: What really happened aboard Air France 447

#144

Post by abk »

nikcub wrote: post #124
abk wrote: post #114

Earlier quoted context omitted.

Surely there must be more to it. Clearly all of us who've played a flight simulator know that going up too fast will cause you to lose speed and eventually stall and fall until you regain enough speed to stabilize. Sadly in this case it sounds like a mix of overconfidence (not avoiding the storm, trusting the plane more than the stall warnings, not waking up the captain until it was too late) and a lack of training f…

I was thinking about that after reading the report. From our perspective it might be obvious, but we can't put ourselves into that situation. I wonder if civillian pilots can be trained in the same way as military pilots to handle stresses in emergencies and to think clearly. Or to at least learn something from military techniques

Yeah I'm curious about that too.

It seems that in the very rare cases where a commercial plane goes down spectacularly, the ones that make it alive were flown by formerly non-commercial pilots (military or otherwise), who've flown planes that give them much less assistance and in much more stressful situations and so "doing the right thing" has almost become second nature to them.

The problem with people is that even if you know what you should be doing in theory, when you're put in an extremely stressful situation you're unlikely to be able to come up with a creative solution... and few situations are more stressful than the moment you realize that something completely unexpected is happening, at night, in a thunderstorm, over the ocean, with 200+ lives depending 100% on your actions.

Re: What really happened aboard Air France 447

#145

Post by ncw »

bambax wrote: post #115
jonah wrote: post #89

Earlier quoted context omitted.

That was the first thing I noted in reading this. Is there any discussion as to why they didn't seek an alternate plan and if not, is this something that needs to or has been remedied?

> Is there any discussion as to why they didn't seek an alternate plan The Captain chose not to, because he "wasn't afraid of clouds" (see my comment above). This was a huge mistake. But Captains are in charge of their route and it makes sense; it would be incredibly bureaucratic and dangerous if routes were decided from a central command somewhere at the airline headquarters... What we need are humble pilots; there…

Would the weather radar not being set up correctly have played a part in the reasoning of the captain?

Re: What really happened aboard Air France 447

#146

Post by bambax »

einhverfr wrote: post #128
bambax wrote: post #112

Earlier quoted context omitted.

What's missing from this article is the fact that the Captain chose to fly right into the storm, saying "on va pas se laisser emmerder par des cunimbs" (in essence: "fuck this storm") http://www.lexpress.fr/actualites/2/actualite/des-dialogues-... This is incredible hubris. Then, in the middle of the storm he leaves the two copilots alone, one of them quite inexperienced, and goes for a nap. He's obviously trying to…

IANA Pilot. I do make aerodynamically correct fixed-wing and lifting-body type paper airplanes, however, and I have had a LOT of fun playing with aerodynamics in this hobby. One thing to keep in mind regaring stall is that it's 100% dependent on angle of attack, not speed (something Popular Mechanics gets entirely wrong). What happens basically is that at a high angle of attack the air layer doesn't track the wing su…

A commenter below (cellularmitosis) makes a very interesting point: Bonin may not have realized he was in "alternate law" (let's call it "mode" instead of "law").

In "normal mode" the computer will not let pilots stall the plane, whatever they do; it will accept the commands up to what it considers dangerous. There's an "envelope" of acceptable plane movements; pilots can move inside this envelope but not outside of it.

In "alternate mode", the envelope is much wider and you can actually stall the plane.

If you're in normal mode, it makes sense to pull the stick all the way so that you're at the edge of the envelope: you climb as fast as you possibly can (as fast as the computer will let you).

And you can probably fool yourself when the stall alarm rings: the computer is telling me I'm near stalling -- I'm at the edge of the envelope, THIS IS WHAT I WANT!!

In fact you're not in normal mode anymore, and the computer is telling you that you're way past the envelope. But you can't register that, because for you that is simply impossible.

If that's what happened, the cause of the crash is insufficient training in alternate mode.

Re: What really happened aboard Air France 447

#147

Post by yardie »

sandee wrote: post #63
runningdogx wrote: post #29

I've followed the discussion of the AF447 investigation on several flight discussion forums. The PF (Bonin) apparently never became aware of his angle of attack (once the airplane fully stalled, AOA was absurdly high). He did not seem to be aware that his constant inputs had caused the Airbus's THS (trimmable horizontal stabilizer, horizontal flaps on the tail) to deflect to maximum in order to try to keep the nose u…

>at night, over an ocean, in a storm, with no visibility, in possibly significant turbulance Instead of finding out strategies on how to fly under these circumstances, why can't the plane change its course, if they anticipate the flying route to have these conditions. How about running some reconnaissance drones in the popular routes if they suspect a bad weather and want to check out. Or try out better weather monit…

1. This is a region that is quite regular with thunderstorms. The captain probably assumed this was like any other storm in this area any other day of the week.

2. This route is at the upperlimit this plane configuration can fly. If they had to reroute they would need to stop and refuel in another country, possibly Spain, Senegal or Morocco. I assume the captain didn't want to do this and soldiered ahead.

Re: What really happened aboard Air France 447

#148

Post by LaGrange »

nodesocket wrote: post #94
Klinky wrote: post #30

Co-pilot Robert, after finally getting full control back from Co-pilot Bonin: "Damn it, we're going to crash... This can't be happening!" Co-pilot Bonin, who had been pulling back & stalling the plane during the crisis: "But what's happening?" Pretty much sums it up. I am thinking that perhaps Bonin had shellshock & may not have even realized he was holding the stick back. Perhaps the more experienced Robert didn't t…

This one feature may have prevented the crash. A indicator light, saying the plan is in "alternate law" mode, and SHIT can go wrong, very quickly. Also an alarm in the pilot resting area that would relay when warnings are detected like stall or switching to alternate law.

Okay. This is how the cockpit apparently looks: http://www.pbase.com/image/47231836

Where are you going to stick the indicator light so that it's impossible to ignore it or mistake it for something else.

Re: What really happened aboard Air France 447

#149

Post by xiaomai »

StavrosK wrote: post #143
Klinky wrote: post #30

Co-pilot Robert, after finally getting full control back from Co-pilot Bonin: "Damn it, we're going to crash... This can't be happening!" Co-pilot Bonin, who had been pulling back & stalling the plane during the crisis: "But what's happening?" Pretty much sums it up. I am thinking that perhaps Bonin had shellshock & may not have even realized he was holding the stick back. Perhaps the more experienced Robert didn't t…

What I don't get is why THE HELL are the two sticks averaged? What's the reasoning behind this? "Hey, one pilot thinks we should descend, the other we should climb, better maintain altitude without telling either one about it". Why?

I found that really bizarre as well. It's also troubling to me that the sticks don't move in concert. That seems like an excellent mode of communicating what the other pilot is doing.

Re: What really happened aboard Air France 447

#150

Post by StavrosK »

xiaomai wrote: post #149
StavrosK wrote: post #143

Earlier quoted context omitted.

What I don't get is why THE HELL are the two sticks averaged? What's the reasoning behind this? "Hey, one pilot thinks we should descend, the other we should climb, better maintain altitude without telling either one about it". Why?

I found that really bizarre as well. It's also troubling to me that the sticks don't move in concert. That seems like an excellent mode of communicating what the other pilot is doing.

Exactly. I fail to see any benefit to removing feedback on how the plane is actually contolled at any given moment.
Post reply on HN