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Comment by tomglynch | Hacker News Reader

I posted this as a comment the other day in another Boeing and MCAS discussion.

In my research into the topic the saddest bit of information I've seen is the image of the black box data for the flight (the first crash): https://i.imgur.com/WJuhjlO.png You can see from the graph that in the final minutes and seconds, the pilot put insane amounts of force on the control column (aka the yoke) to try to pull the plane out of the dive - to save the 189 people on board. But no, MCAS was overpowering and lacked the documentation for the pilot to try anything else.

Also interesting to see is the amount of times the pilots bring the nose up, only for MCAS to kick in and force the nose back down. 26 times.

All data from this Seattle Times article, which was written before the second crash occurred: [1] https://www.seattletimes.com/business/boeing-aerospace/black...

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If the pilots were putting that much force on the yoke it is pretty apparent that the pilots really truly wanted the plan to do what they asked of it.

I am curious what scenarios the designers of the plan drove then to not trust that the human in the seat really has no idea what they are doing. Was the ignoring the wishes of the pilot and attempt to prevent a crazed irresponsible and unlicensed idiot from doing something? These are trained humans why does the computer totally ignore there efforts?

You make it sound like the plane has some kind of agency. Though a plane is very complicated, the treacherous MCAS system is actually very simple.

If it only were that simple. Airbus in particular has a lot of systems which PREVENT the human from doing things.

One plane actually crashed because the prevention system disabled itself and the pilots believed it was still there to protect them from bad actions on their part:

> caused the autopilot to disconnect, after which the crew reacted incorrectly and ultimately caused the aircraft to enter an aerodynamic stall, from which it did not recover

https://en.wikipedia.org/wiki/Air_France_Flight_447

It seems a bit rough that you're getting downvotes. [Edit: The parent was grey when I wrote this].

AF447 seems like a pretty important case study for figuring out where to put the balance of trust. Along with the very final stage of Aeroflot 593 (after the child had left the seat), also mentioned.

There's a few more: Colgan Air 3407, AirAsia 8501, Korean 501, etc, where flight crew ignored or overrode systems. Which is not to deny that in the majority of cases the flight crew are the best judge of what is needed, just that one surely has to look critically and honestly at counter examples.

There is of course also Germanwings 9525, though as the GP implies, systems protecting against malicious piloting will probably be counter-productive.

I liked the part where it would turn off the stall warning when the nose was too high, then turn them back on again when the nose dropped, which may have convinced the copilot that holding the stick back was helping.

AF447 is fascinating for other reasons as well - on Airbus it is possible for two pilots to provide directly opposite control inputs because there is no mechanical linkage between the sidesticks, unlike on yokes in most other airplanes. It does produce a warning (dual input) but it is not tactile - you cannot feel what the other crew member is doing.

https://en.wikipedia.org/wiki/Armavia_Flight_967 https://en.wikipedia.org/wiki/Indonesia_AirAsia_Flight_8501 https://www.youtube.com/watch?v=8F5bRxTIn24

A pretty extreme UX issue.

Perhaps related crash[0] where the autopilot was disabled because it was listening to user input, in this case a child.

[0] https://en.wikipedia.org/wiki/Aeroflot_Flight_593#Accident

That was interesting and horrific.

Oooof. Well the real lesson there is that unqualified people (especially children) shouldn't be in the cockpit of an airliner at all. Autopilot can't be made smart enough to determine if the person operating the controls actually knows what they're doing, and thus to follow/ignore them as appropriate.

I mean, pick your poison. Either the humans are more reliable or the computers are. Either way is subject to some level of fallibility.

The wikipedia article calls out that the compounding sequence of issues started when autopilot was silently disabled, so the human system was in control when the pilots did not intend it to be.

I think the critical issue in both cases is that the wrong system was in control against the pilots wishes.

So, the pilots can pick my poison based on their training and best judgement (and maybe not put their children in control?).

That was because the pilots were not aware that the autopilot had been disabled.

Pulling on the yoke 26 times, as hard as you possibly can, is a bit different.

Direct link to image bypassing imgur’s awful interface: https://i.imgur.com/WJuhjlO_d.jpg?maxwidth=1640&shape=thumb&...

Thank you, forcing everyone onto a landing and wasting loads of data just rendering the garbage page is the worst UX on the planet.

I disagree, It is a free image hosting platform for sharing images. There is nothing wrong with linking to it.

If you upload or want to share what is on the platform, they would prefer if you link it that way, as is their right.

It is a business after all. And If people want to hotlink directly to an image they should pay up and host it themselves.

I don’t disagree that if people want to be able to hot-link images they should pay for the hosting themselves (It’s something I do myself - instead of replying on imgur I just pay to host the files on S3).

I just find it amusing that imgur was born out of being a better image host then the competition as linking to images on reddit at the time sucked, and now (IMO) has turned to “the dark side” and are doing the things that made the competition so crappy to start with.

I’m not saying they shouldn’t show ads but I’ve seen and reported countless bad ads on the site (forced redirects away from the site, unannounced “would you like to open the App Store” dialogs. APKs just auto downloading. Seemed at the time they or their ad network would accept any old crap of an advert (this was a quite a while ago, hopefully they are more choosing about the ads they run).

Also their UI is a pain in the arse (IMO) on mobile Safari it’s a pain in the arse to pinch and zoom (not that it will do any good as the image on mobile UI has been resized) and getting to the full sized image is another pain in the arse. For images like above it makes it impossible to read. They said look at the force applied but the wording on the scale is just a blur making the graph hard to understand.

It’s their site and they can do what they like with it. I just find it amusing that (IMO) they have become what they hated. At least they managed to include reddit style communities/comments before reddit started hosting images themselves.

> they have become what they hated

I think that's the fate of all image hosts: current offerings have a lot of (crappy) ads to pay for hosting => competitors arrives, starts with less ads to incite onboarding => competitors gets a market share => competitors now has to turn a profit => add more ads (or ask money for hosting)

Thing is imgur was profitable (before reddit became its own image host, dunno what their status is these days, I just know there submission numbers dropped sharply after reddit did that, but maybe their own community was able to recover from that).

Back in the day you used to be able to pay to upgrade your imgur account to allow larger file uploads (which was great for gifs), disable the ads you saw site wide and disable the ads people saw coming to your submissions. I guess the Rev they were generating off ads back in 2015 was out stripping the Rev generated from Pro accounts (esp with the ability to prevent ads on your submissions. If you were a imgur pro user you were either trying to support that platform or was a power user and getting a fair few visits to your submissions) because that’s when they they dropped them and they were reporting as profitable back then. Which is odd (to me) because it’s been since then that the service (IMO) has gotten worse. To me they had a winning formula and the user base to make it work but fucked it up (or not, they are still around today. So maybe they did the right thing, I’m just an old grumpy user who doesn’t like change. Now get off my lawn, I have clouds to shout at...)

Interesting that there are two angle of attack sensor readings in the black box image when the major issue with MCAS seems to be that it was relying on only a single sensor?

MCAS use(s/d) one sensor at a time, rotating which one is used.

Apart from at the start (when the plane is on the ground), both sensors seem to report the same data?

So why did it crash?

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