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

181–190 of 374 posts

Re: What really happened aboard Air France 447

#181

Post by mtts »

nikcub wrote: post #86

I simply don't undersand (or don't comprehend) how the pilots don't know these things. My knowledge of planes is 4 hours of pilot lessons and watching a few documentaries on the Discovery channel yet I know that pulling the nose up of a plane would stall, that when you get bad readings from instruments you cross-check, and that a frozen pitot tube giving bad airspeed readings is very likely in high-altitude storms. I…

At night, over an ocean, in a storm, with no visibility, in possibly significant turbulance and responsible for the lives of 300 people. I doubt knowledge acquired from an episode of "Air Crash Investigation" is very useful in such a case.

Watching documentaries or looking up stuff on the internet does not make anyone an expert. That Bonin guy, as inexperienced as he was, knows far, far more about piloting airplanes than you do.

Re: What really happened aboard Air France 447

#183

Post by andrewmccall »

Too wrote: post #153
greiskul wrote: post #14

Earlier quoted context omitted.

Which raises a very good question, when would you ever want that joystick behaviour?

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.

This is likely the reason, and probably not just as a cheap work around, in most day to day situations it's probably the desired effect since both sticks are independent and don't move in reaction to the other.

Re: What really happened aboard Air France 447

#184

Post by sek »

brazzy wrote: post #173
sek wrote: post #163

One question: Why are they not speaking English? I heard from fatal command mistakes with pilots an Asian country and now everyone has to speak English. Is this again some stupid patriotism thing (i am German, i know the French attitudes), but i seriously thought to prevent command errors everyone has to speak the international aviation language.

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 afraid to speak up to his tired captain that they died. Another change after that incident was to make a new flight team every time.

Re: What really happened aboard Air France 447

#185

Post by mtts »

ookblah wrote: post #61

Such a tragedy... Forgive my ignorance, maybe some pilots can shed some light on this. In the article it mentions that even though the plane was flying in "alternate" mode, my understanding is that it still has limits to what inputs can be given. That said, even if autopilot is off, why wouldn't the computer have emergency functions to negate strange situations like this? When would pulling completely back on the sti…

There is a famous incident with an A330 test flight where the auto pilot system happily flew into the ground precisely because, unlike Bonin, it did not panic and give in to the instinct to pull the nose back up.

I'm guessing this incident made the engineers who designed the plane a little more eager to provide for a true unhampered manual override.

Re: What really happened aboard Air France 447

#186

Post by xtracto »

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 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 stick controllers Summers et al (1987) found that under simulated ‘surprise’ hand overs pilots Cooper Harper rating of the schemes were (in descending order):

    Coupled sides sticks with algebraically summed inputs (1.4),
    Uncoupled side sticks with algebraically summed inputs and disconnect switch (final A320 implementation) (1.8),
    Uncoupled with algebraically summed inputs and priority logic (original A320 implementation) (3.3), and
    Uncoupled side sticks with with algebraically summed inputs (3.4).
So, Airbus chose to implement the "second best" option (using a disconnect switch). The same article speculates that even though several sound alerts might have been triggered - including a sound alerting of "Dual Input" -, the stress situation makes them insufficient:

    [...] in the circumstances identified as triggering instinctive responses the value of such alerts is degraded due to the inevitable attentional tunnelling that operators experience in high stress situations.

Re: What really happened aboard Air France 447

#187

Post by rwmj »

Simon_M wrote: post #158
nikcub wrote: post #110

Earlier quoted context omitted.

the other similar incidents are Birgenair Flight 301, where the pitot tubes were blocked because of insect nests, resulting in pilot confusion: http://en.wikipedia.org/wiki/Birgenair_Flight_301 and Aeroperu Flight 603, where the pitot tubes had been covered by maintenance workers and not removed prior to takeoff, also resulting in pilot confusion and lack of confidence in instrument readings: http://en.wikipedia.org/…

Considering how many incidents there seems to be due to the loss of these airspeed sensors it seems crazy not to have an additional, different method of calculating airspeed. Is there a reason GPS is not suitable here?

GPS gives you ground speed. Airspeed is a different thing -- imagine if you're flying into a strong headwind.

Re: What really happened aboard Air France 447

#188

Post by nikcub »

mtts wrote: post #181
nikcub wrote: post #86

I simply don't undersand (or don't comprehend) how the pilots don't know these things. My knowledge of planes is 4 hours of pilot lessons and watching a few documentaries on the Discovery channel yet I know that pulling the nose up of a plane would stall, that when you get bad readings from instruments you cross-check, and that a frozen pitot tube giving bad airspeed readings is very likely in high-altitude storms. I…

At night, over an ocean, in a storm, with no visibility, in possibly significant turbulance and responsible for the lives of 300 people. I doubt knowledge acquired from an episode of "Air Crash Investigation" is very useful in such a case. Watching documentaries or looking up stuff on the internet does not make anyone an expert. That Bonin guy, as inexperienced as he was, knows far, far more about piloting airplanes…

ye no shit, and I am thinking through how the situation gets to a point where he can forget all that and keep pulling the stick back up

Re: What really happened aboard Air France 447

#189

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…

I double checked, AOA sensors are weather-vane type systems.

Re: What really happened aboard Air France 447

#190

Post by Shivetya »

nikcub wrote: post #110
bhickey wrote: post #68

Earlier quoted context omitted.

The NTSB concluded that 990 was a homicide. A relief pilot assumed control after take-off and then deliberately crashed the aircraft. From what I hear, it wasn't a fun week at the RI Medical Examiner's office.

the other similar incidents are Birgenair Flight 301, where the pitot tubes were blocked because of insect nests, resulting in pilot confusion: http://en.wikipedia.org/wiki/Birgenair_Flight_301 and Aeroperu Flight 603, where the pitot tubes had been covered by maintenance workers and not removed prior to takeoff, also resulting in pilot confusion and lack of confidence in instrument readings: http://en.wikipedia.org/…

let alone we forget losing a B2 bomber during take off for similar reasons.

http://en.wikipedia.org/wiki/Andersen_Air_Force_Base_B-2_acc...

Post reply on HN