What really happened aboard Air France 447 • Hacker News Board

Re: What really happened aboard Air France 447

#301

Post by assemble » Thu, Dec 08, 2011, 7:39 PM UTC

Nick_C wrote: post #136

teyc wrote: post #126

Earlier quoted context omitted.

There's actually a tendency to reduce the number of different alarms and use screen information to indicate the problem Yes, that'd be good UX. There should be only one actionable task presented at any time to correct errors. In any case, user testing is more important than guidelines. I wonder if grouped alarms make any sense. For instance you can group all alarms related to stalling together, and present the one th…

With the Qantas incident, they had something like 146 msgs appear on the screen spread over about 5 or 6 pages. So they were forcibly distracted from solving the problem from a top-down approach to having to investigate and cancel each of the 146 msgs, and that was why the two extra pilots were such a godsend, they were able to help out.

Messages are prioritized on the screens in the cockpit in any aircraft I've ever seen. Higher priority messages are near the top and are a different color.

There are lots of messages because lots of things can go wrong with an aircraft. They aren't all critical "land now" messages, but may be relevant.

Re: What really happened aboard Air France 447

#302

Post by joshAg » Thu, Dec 08, 2011, 7:41 PM UTC

crikli wrote: post #256

joshAg wrote: post #140

Earlier quoted context omitted.

when instruments were first introduced to planes, most people thought that something caused all instruments to malfunction like crazy as soon as they entered clouds due to the ghost spatial effects the pilots assumed were true ("I can't be turning, I feel like I'm going in a straight line!" or "I can't be going straight, I feel like I'm turning"). If I remember correctly, the average lifetime of a non-instrument trai…

There was a thread on here recently about this: http://news.ycombinator.com/item?id=3144099 I think my comment on the subject is near the top: to summarize, it's not as dramatic as all that. :)

that's the article i was thinking of! i still think 178 seconds is insanely short, though.

Re: What really happened aboard Air France 447

#303

Post by assemble » Thu, Dec 08, 2011, 7:42 PM UTC

jarek wrote: post #138

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…

The autopilot turning off altogether is the biggest equipment problem here (along with averaging/independent sticks). An alarm will surely be necessary but I don't see how killing off autopilot helps since the pilots probably won't have any better of an idea. Perhaps this specific incident caught an ugly edge case. There is actually a fair amount of ergonomics and interfaces design that goes into these systems - at l…

Try writing the code for an autopilot some time. It's hard. We spend a lot of time flight testing just the autopilot.

Making something go in a particular direction at a particular altitude at a particular speed is hard enough. Throw in a stall and the best the plane can do is try to nose down.

Re: What really happened aboard Air France 447

#304

Post by waqf » Thu, Dec 08, 2011, 7:58 PM UTC

deadmansshoes wrote: post #169

I hope the analysis of the flight was more accurate than some of the translations. 02:08:03 (Robert) Tu peux éventuellement le tirer un peu à gauche. You can eventually pull it a little to the left. Eventuellement is not the French equivalent of the English. It should be "You could pull a little to the left." Many sentences read like a straight copy and paste from Google Translate.

Yes. The translations, while basically accurate, don't do a good job of conveying the tone of remarks, which is important in analyzing the situation.

Re: What really happened aboard Air France 447

#305

Post by abstractbill » Thu, Dec 08, 2011, 8:13 PM UTC

krschultz wrote: post #243

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…

I find the fact that the control sticks do not move together the most troubling design flaw. Bonin's actions were not obvious to the other two pilots, if the other pilot saw his stick pulled all the way back when he knows they need to get the nose down and pick up airspeed, he'd instantly know what was wrong. Instead he is looking at instruments and talking to the other pilot and is completely unaware of how self-inf…

That, and the fact that the computer chooses to average inputs from the two sets of controls even when they're very different. One pilot pulling back, and the other pushing forward and the system just quietly averages them out rather than sounding another alarm?

Re: What really happened aboard Air France 447

#306

Post by jader201 » Thu, Dec 08, 2011, 8:38 PM UTC

For those interested and not already aware, PBS aired a documentary about this on Feb. 16, 2011.

http://www.pbs.org/wgbh/nova/space/crash-flight-447.html

Re: What really happened aboard Air France 447

#307

Post by crististm » Thu, Dec 08, 2011, 8:52 PM UTC

acabal wrote: post #48

That was one of the tensest things I've read in a while. My heart was pumping up until the end. The level of stress, confusion, and terror those pilots, not to mention the passengers, must have experienced must have been truly terrible.

My thoughts exactly. While reading this I could not think about the same counter-intuitive reaction that people have when they drive and the car slips. Most people steer in the direction of the road when the single action to regain control is to slightly steer in the direction of the slippage.

Re: What really happened aboard Air France 447

#308

Post by crististm » Thu, Dec 08, 2011, 8:58 PM UTC

maximusprime wrote: post #182

scary how incompetent they seem

They did not have enough training in such situations. The captain seemed more competent, but he was not on the controls to do the right thing. It's the same situation when untrained people drive cars to their limit. If the car slips then you should slightly steer in the direction of the slippage which is most of the time opposite to where the road turns. If you're not trained to do that you won't do it.

Re: What really happened aboard Air France 447

#309

Post by js2 » Thu, Dec 08, 2011, 8:59 PM UTC

js2 wrote: post #291

Priority logic on the dual-sticks. Each stick has a take-over button. From http://www.smartcockpit.com/data/pdfs/plane/airbus/A330/misc... • Normal operation: Captain and First Officer inputs are algebrically summed. • Autopilot disconnect pushbutton is used at take-over button. • Last pilot who depressed and holds take-over button has priority; other pilot’s inputs ignored. • Priority annunciation: - in front of eac…

This is wrong, but I can no longer delete the comment. It's based on an outdated source. Sorry for the noise.

Re: What really happened aboard Air France 447

#310

Post by chc » Thu, Dec 08, 2011, 9:02 PM UTC

lutorm wrote: post #231

onli wrote: post #202

Earlier quoted context omitted.

It's especially frustrating for me because i remember all the times i crashed in a simulator due to stall until i understood what was happening. I don't even remember the name of the simulator, i'm not even an amateur-pilot - but that makes that report almost unbelievable, that something like this happened in a real flight to a real pilot.

unbelievable, that something like this happened in a real flight to a real pilot Actually, most fatal crashes are "stall-spin accidents", where pilots stall the airplane near the ground without sufficient altitude to recover. But those are not cases where you keep the airplane in a deep stall for 90s. When you stall an airplane in VFR, it's obvious what happens. No one would persist in keeping the airplane at 20 degr…

Actually, only the less experienced copilot, Bonin, appeared to be in favor of climbing. The other repeatedly told him to level out or dive, and apparently thought Bonin had listened (which would explain why he was so baffled). As the OP points out, neither that copilot nor the captain seemed to realize that Bonin had been futilely trying to climb the whole time until that moment at the end when the captain ordered him to stop.