What really happened aboard Air France 447 • Hacker News Board

Re: What really happened aboard Air France 447

#361

Post by omegant » Sat, Dec 10, 2011, 3:37 PM UTC

bdonlan wrote: post #42

jarcoal wrote: post #40

Earlier quoted context omitted.

Supposedly they do de-ice themselves, but that obv didn't work properly here.

According to the article, the pitots did, in fact, de-ice and return to normal functioning. However, apparently the alternate law needs to be manually reset, since the plane remained in direct input mode, and thus the pilots managed to stall the plane even though its instruments had all recovered.

Pitot tubes are always under strong heating during flight( so strong that the steel may blue). The problem with the 330 pitots brand in particular( there are several ) is that they cant evacuate water fast enought and sometimes they could become unserviceable ( as it happened to the af ) as they don't sense air preasure anymore.

Re: What really happened aboard Air France 447

#362

Post by omegant » Sat, Dec 10, 2011, 3:59 PM UTC

assemble wrote: post #303

jarek wrote: post #138

Earlier quoted context omitted.

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.

Well not at 400' and 130knots... That is way they were performing a windshear maneuver ( incorrectly) at FL 340.

Re: What really happened aboard Air France 447

#363

Post by omegant » Sat, Dec 10, 2011, 4:04 PM UTC

tcarnell wrote: post #214

Too wrote: post #153

Earlier quoted context omitted.

I guess it could be a cheap workaround to always get smooth transitions when changing pilot. Imagine if one pilot holds full left and the other full right and you press a "switch now!"-button. You would need some kind of transition-period of maybe a second to avoid jerk which could be confusing for the pilot to not know when he has full control and when he is in transition.

good point - but I think a 'dual input' mode is the wrong solution to that problem.

Simply is the cheapest when you want to go all digital.

Re: What really happened aboard Air France 447

#364

Post by omegant » Sat, Dec 10, 2011, 4:06 PM UTC

tcarnell wrote: post #214

Too wrote: post #153

Earlier quoted context omitted.

I guess it could be a cheap workaround to always get smooth transitions when changing pilot. Imagine if one pilot holds full left and the other full right and you press a "switch now!"-button. You would need some kind of transition-period of maybe a second to avoid jerk which could be confusing for the pilot to not know when he has full control and when he is in transition.

good point - but I think a 'dual input' mode is the wrong solution to that problem.

Simply is the cheapest when you want to go all digital.

Re: What really happened aboard Air France 447

#365

Post by bond » Sat, Dec 10, 2011, 9:27 PM UTC

I just can't believe a pilot would keep putting pressure after stalling the plane. What the hell was he thinking that stall warning was?...

Re: What really happened aboard Air France 447

#366

Post by minitrollster » Sun, Dec 11, 2011, 2:43 AM UTC

sek wrote: post #184

brazzy wrote: post #173

Earlier quoted context omitted.

You seriously believe that command errors are less likely when two people communicate in a foreign language, compared to a shared native one?

This sounds funny first, but i have read about this in a book i can't recall right now. Especially asian countries have a extreme passive and submissive language. The receiver is responsible to interpret the language. In this fatal example, the lower ranked pilot said something like "our altimeter was very fortunate in the past" and what he tried to communicate was "look at the altimeter, we are to low". He was so af…

I know this is a bit late, but I just wanted to mention that you most likely read that in Malcom Gladwell's Outliers. There's a whole chapter about aviation.

Re: What really happened aboard Air France 447

#367

Post by reddit_clone » Sun, Dec 11, 2011, 5:38 AM UTC

I am pretty ignorant about avionics.

First off, I find it surprising that there are two people controlling an air plane. I always thought that one guy had the reins and other guys helped him out.

Now I learn that there are computers in between the two guys averaging them out!

Re: What really happened aboard Air France 447

#368

Post by reddit_clone » Sun, Dec 11, 2011, 5:49 AM UTC

snowwrestler wrote: post #273

LaGrange wrote: post #148

Earlier quoted context omitted.

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.

Some ideas: Illuminate the pilot's footwells with a bright red light. There is normally no illumination there at all, plus it takes up a fairly large percentage of their viewable area when looking at their screens. Or, change the background colors of all the screens from black to red. That might harm usability too much though. Maybe change all the other switch backlighting over to red. Or change the cabin overhead li…

> Illuminate the pilot's footwells with a bright red light

Might interfere with normal/night vision.

Re: What really happened aboard Air France 447

#369

Post by benohear » Sun, Dec 11, 2011, 11:39 AM UTC

DasIch wrote: post #348

brc wrote: post #82

Earlier quoted context omitted.

This is an important point as cars nowadays have more and more electronic overrides - everything from traction control to stability control to anti-lock brakes to lane departure warnings (and recovery) to emergency braking and speed control. Most of the later ones (emergency braking, speed control, lane departure) are only on expensvie cars, but within 10 years will be standard equipment on all cars. If not by legisl…

Getting a drivers licence in Germany costs roughly 2000€ (2673$), assuming you pass theoretical and practical exams on first try. You need to take 14 theoretical lessons at 90 minutes, 2 of them on technical stuff, you need at least 12 practical lessons, 5 outside of a town, 4 on the autobahn, 3 at night and you will need a couple regular lessons just to get started so most people end up with 20 practical lessons or…

I was recently thinking that they should introduce driving simulators as part of the training, in order to expose drivers to dangerous situations like they do with pilots.

Incidentally go-karting is a pretty good way to get some "on the edge" experience. I pretty much passed my (Swiss) driving license on the quality of my braking, which I picked up on a couple of go-kart outings.

Re: What really happened aboard Air France 447

#370

Post by delackner » Mon, Dec 12, 2011, 5:36 AM UTC

xtracto wrote: post #186

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 was also really surprised about this after reading the article. I look around to know a bit more about the Airbus design and arrived at this [article]( http://msquair.wordpress.com/2011/09/16/pilots-in-the-loop-a... ). The problem is not that they are averaged, but it seems to be that they are not coupled. It seems that it has been known since 1987 that pilots prefer coupled sticks: In a 1987 evaluation of side sti…

Fascinating and crushingly disheartening. It is obvious that a coupled force feedback mechanism is the simplest human interface solution to showing what is happening between both sticks, and pilots prefer it. I would really LOVE to hear the thinking behind the fool that chose to produce an interface that allows for me to press "up" and you to press "down" and we each get fed the bogus result "up" or "down" while actually it has decided to process it as "asdfasdf".