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

201–210 of 374 posts

Re: What really happened aboard Air France 447

#201

Post by teyc »

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.

Yes, a message flood is also a failure of UX. At my place of work, when a flood of errors occur, we throttle and batch the errors so that the admin doesn't get thousands of emails.

Given that user interfaces on airplanes are digital now, there are a lot of opportunities to innovate.

For instance, where there are multiple failures and alarms, it might be better for the panel to continuously replay the sequence in which the alarms were set off, more or less like how movies do it to help the viewer understand what is happening on the computer. By showing how a system is failing through time, it shows a causal relationship. In addition, you can provide drill down capabilities.

In the case of Air France, perhaps it could have illustrated the AoA through time, and the flight velocity. Perhaps that would have explained something to the pilot.

Re: What really happened aboard Air France 447

#202

Post by onli »

StavrosK wrote: post #154
gnaffle wrote: post #151

Earlier quoted context omitted.

From what I read from the preliminary report, it's established that the stall warning sounded. If it had not been audible on the CVR, they would probably have noted it. One problem was that the stall warning stopped due to high angle of attack even though the plane was stalled, and it started again when the nose was lowered and the AOA was in the "valid" region again. This might have confused the pilots in a situatio…

Ah, yes, I read that too. It was so frustrating that the pilot kept pulling up all the time, it makes no sense. You'd think that at some point he'd stop and reassess, but I guess he was too confused and shocked to do it...

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.

Re: What really happened aboard Air France 447

#203

Post by gnaffle »

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…

I agree it's difficult to understand. I think a combination of confusion, distrust in the instruments and and a belief that the airplane would not stall must have contributed.

The PNF acknowledges "alternate law", if he had only made the PF aware of the implications of that, maybe he would have "snapped out of it" and stopped pulling up.

At some point during your training or flying career you'll probably have situations where in hindsight you'll try to understand why you acted a certain way despite knowing better. I've certainly encountered situations like that.

I think most commercial pilots today in a way have to be enthusiasts, or at least start out as one. The job market is simply too uncertain and cost of education so high that you really have like flying to go through with it. But keeping the enthusiasm in a job with a busy schedule and demanding family life might not be so easy. That's one reason why I don't plan on flying for a living.

Re: What really happened aboard Air France 447

#205

Post by stef25 »

blinkingled wrote: post #18

The men are utterly failing to engage in an important process known as crew resource management, or CRM. They are failing, essentially, to cooperate. It is not clear to either one of them who is responsible for what, and who is doing what. I have read a few other transcripts from crashed planes and this seems to be the most common and significant contributor. I see variations of this problem almost daily in my day to…

In one of Malcolm Gladwell's books he talks about air crash scenarios, citing several cases where copilots were 'scared' of pointing out errors that they thought were being made by their captains. I think it was Korean airlines that lost a few planes this way, essentially through a lack of communication.

They brought in some guy to retrain the pilots and they never had the problem again.

Re: What really happened aboard Air France 447

#206

Post by al_james »

andrewmccall wrote: post #170
Simon_M wrote: post #158

Earlier quoted context omitted.

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 can only tell you how fast you're moving over the ground. It can't tell you how fast you're moving through an airmass that might be moving with or against you, this is far more important to keeping a plane in the air than how fast you're moving between point a and point b.

I wonder if GPS could be used to estimate the air speed by means of a permanently refining mathematical model? E.g. If I know I have heading X, ground speed Y, weight Z, thrust A, you should be able to work out your predicted ground speed. Any variation in real ground speed and estimated ground speed is got to me made up of wind direction and velocity right??? Just a thought.

(Disclaimer: I know nothing about aerodynamics so this may be nonsense)

Re: What really happened aboard Air France 447

#207

Post by eftpotrm »

aperiodic wrote: post #177
Simon_M wrote: post #158

Earlier quoted context omitted.

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 speed relative to the ground, not speed relative to the air, which is what's important for aerodynamics.

Yes, but when groundspeed with a slight lag is all that's available is it really that much worse than nothing, which seems to be the failure mode at present?

I stress I'm not a pilot and I'm sure you'd want to have a Big Flashing Warning Light telling you that ground speed air speed, but there'd seem to be some benefit over nothing at all.

Re: What really happened aboard Air France 447

#208

Post by gldalmaso »

brazzy wrote: post #165
bambax wrote: post #146

Earlier quoted context omitted.

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…

Bonin would have had to realize that the plane is in alternate mode in the first place in order to react correctly. It probably never crossed his mind since he never trained in it, and conversely if he had trained in it, he may have been more likely to at least check. But to me the bigger problem seems to be that such an important change in the plane's behaviour could happen without anyone noticing. I'd consider the…

What boggles my mind is that pilots are being trained in anything less than every mode an aircraft operates on.

Re: What really happened aboard Air France 447

#209

Post by tcarnell »

Presumably the stall warnings were ignored because in "normal law" even if you try to stall the plane, a). the plane will not allow itself to stall and b). the stall warning will still sound.

Hence the stall warning SHOULD NEVER SOUND in "normal law" mode.

Therefore, the only time a pilot should hear the stall warning is when they actually have to intervene.

Ultimately, if the plane was funcioning perfectly well and assuming the pilots weren't complete idiots, the problem was a 'usability' issue.

(think again everytime you see a bug logged as 'usability' and assume it is not important!)

Re: What really happened aboard Air France 447

#210

Post by tcarnell »

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…

yes, and I'm not sure under what situation a 'democratic' dual-input mode is a good idea!

Maybe everyone on the plane could have one!

Post reply on HN