Comment by _Understated_ | Hacker News Reader

Comment by _Understated_ | Hacker News Reader

I felt compelled to comment on this as I am somewhat conflicted in my feelings towards the automation of the checking process.

I am all for progress and automation where possible but I also like to put my faith in a human (or multiple humans) then going over it again "just in case"... in this case it would be someone following behind with another torque wrench to make sure the first guy hadn't missed something or was maybe using a defective wrench.

I understand that in many industries, checking samples or batches is the norm. It can make sense. But we're talking about a plane here... the margin for error must be tiny.

If my car develops a fault, hell, even if a wheel fell off while driving, I have a good chance of recovering safely but with a plane, something as catastrophic as my car wheel scenario could be massive. Plus, you can't pull over to the side of the road.

Also, with my security head on, I am questioning the smart wrenches (I confess to knowing nothing about them!). If the torque is electronically programmed, whats to stop hackers tweaking it a bit. Kind of like in Die Hard 2 where the bad guys reset ground level to be -200ft. How would we know?. Could someone change 300nm to be actually 200nm? I assume the inspector will look at an output to verify these things since they won't be going round with their own torque wrench now.

Hackers could have a field day with this as it could be years before the plane develops a massive fault and then you'd never be able to track it.

I've read enough about aircraft computer systems to know that they aren't perfect as it is!

I dunno. This makes me feel a bit uneasy. I always like to think that planes are over-engineered and triple-inspected by many humans for a reason.

Maybe I am looking a bit too deep here!

> I also like to put my faith in a human (or multiple humans) then going over it again "just in case"... in this case it would be someone following behind with another torque wrench to make sure the first guy hadn't missed something or was maybe using a defective wrench.

A second pass with a torque wrench is probably not such a bad idea, but multiple _checks_ by humans is not necessarily beneficial.

A few years ago I worked for a company making small-batch pharmaceuticals (almost exclusively with ingredients drawn and mixed by hand, since the batches were so small), and the consensus (backed by research) there was that adding a second human check made quality worse rather than better - the second checker assumes that the first did the job correctly, and the person doing the work assumes that mistakes will be caught further down the line.

Very interesting, thanks for posting.

No sampling at all? No samples retained for analysis in the event of a problem later?

Depending on the criticality of the actual substances for the given use (both of which were always known), assay of samples may have been required as an in-process control rather than an out-of-band one, too.

By "small-batch" I often mean batches of one-offs, reducing the effectiveness of sampling for quality control!

"By "small-batch" I often mean batches of one-offs, reducing the effectiveness of sampling for quality control!"

But increasing the importance of a sample retained for later analysis I imagine.

The solution is for the checkers to be blind, in that they should have no knowledge of ordering or checks. Everything needs to be independent. It isn't that the second check made quality worse, it is that knowledge that the second check is run made the first or second check less rigorous.

1) inject faults to test the testers

2) test diversity, automated and manual

3) test order inversion

The often used alternative is to "be careful" which is not rigorous.

Indeed, that is the root cause, rather than a second check itself.

But we're talking about a plane here... the margin for error must be tiny.

They're actually surprisingly resilient, being purposefully designed that way. Look at avherald.com for all the things that happen to planes daily, yet don't make the mainstream news because no massive injury or death resulted.

Another thing about airplane faults is that the pilots almost always have time to troubleshoot and take corrective action.

As automation moves on I think we will all have to think these issues through. Do I trust the mass of my fellow humans a bit more than an algorithm and its sensors?

I'd expect them to have two different sets of strengths and weaknesses.

Reply on news.ycombinator.com