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Comment by azalemeth | Hacker News Reader

Not an embraer pilot, but I suspect because (like many larger aircraft) you can't physically see the ailerons from the cockpit – that is why the big jets measure the deflection and (should) show it to you.

Part of me wonders if also as long as you see the ailerons _move_ you assume they've moved in the right direction. There have been similarly tragic rigging accidents in GA aircraft as well – and 38 incidences of aileron mis-connection in gliders between 1974 and 2014 reported in the UK. [1]

[1] https://members.gliding.co.uk/wp-content/uploads/sites/3/201...

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as a pilot, I have to really force myself to 'see' that the aileron is moving the correct direction. Not because it's hard, but because my lizard brain wants so badly to skip over the thing that it has seen so many times that it's no longer interesting.

I have not seen a glider where it is physically possible to cross-connect the controls simply through the process of de-rigging and rigging (removing and replacing the wings and stabilizer, which is often done for transport or storage), though I imagine there were examples in the past. I have, however, seen ones where the controls can be left unconnected or even insecurely connected (though such designs now seem deprecated), in which case they may move in the correct direction on the ground, but fail to do so under load (and may flutter). On account of these possibilities, the visual inspection and pull/twist test of the connections, together with positive control checks (where someone holds the surface to provide resistance), as mentioned in the article you link to, should be SOP.

>I have not seen a glider where it is physically possible to cross-connect the controls simply through the process of de-rigging and rigging (removing and replacing the wings and stabilizer, which is often done for transport or storage), though I imagine there were examples in the past

The instances in the past probably caused the newer ones to make that impossible

Absolutely - in aviation generally, not just gliders, and also for electrical and hydraulic connections. That's why Embraer's design choice and justification for it provokes a 'WTF?'

I would think one of the pilots would stand behind the plane and verify control surfaces via radio, but I guess that's too time consuming or error prone?

Works fine for cars though. Drive through lube shops and states with safety inspections will perform indicator checks this way. If you push the left blinker and the right light starts flashing you've got a problem...

Hopefully by now the cockpit has access to external cameras to visualize what's happening behind them in real time

Watch the Mentour Pilot video; there was a display in the cockpit which showed the actual control surface movement. Why didn't they catch it? I'd guess it was because they were just a regular flight crew as opposed to acceptance test pilots, had never ever seen cross-connected controls before, and when they tested the controls they saw "yep, the surfaces moved" and it just didn't register that some of them were in the wrong direction.

The primary issue is that once the ailerons were fully deflected, the control display turned green - even if they were deflected in the wrong direction. It seems that despite this test having been performed multiple times, everyone involved was subconsciously looking for "It goes green" and not "It moves in the right direction".

> I would think one of the pilots would stand behind the plane and verify control surfaces via radio, but I guess that's too time consuming or error prone?

Pointless. Reversing of controls is not possible between flights.

After service it should've been on checklist to validate everything (really, if plane's computer have feedback on position it should immediately alert), but, well, I'd imagine after this it will be mandatory anyway

No, but hardware breaks and while it may not be cross-connected, you could have the issue where one aileron or the other doesn't move at all.

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