I had a smartphone that at some point started to randomly create touch events. Kind of like if you put it in your pocket while the screen is unlocked.

I don't remember any physical light switch that ever switch on or off by itself.

In an aircraft flying through turbulences I'd feel a lot more comfortable knowing that all switches are pyhsical. Try to use your smartphone while jogging...

Comparing a light switch to the switches and dials found in an aircraft is a it like comparing a light switch to a keyboard key.

Yeah they’re both switches, but size is incredibly important, and small mechanical devices are finicky and don’t produce nice clean digital output (that’s a lie that electronic engineers tell software engineers to keep things simple).

So yeah I’m sure you’ve never seen a light switch fail, but I bet you’ve seen a keyboard fail (especially if you’ve spent any time around a recent MacBook).

But I do agree with your point on using a touchscreen in turbulence. A counter point is that there are probably hundreds of controls or settings on a plane that you never touch during turbulence, possibly that you never touch in flight (like telling the flight computer how much cargo you’re carrying). Stuff like that is ideal for a touchscreen.

A mechanical switch is easy and cheap to fix or replace. A touch screen is the opposite. It cannot be repaired, only replaced. A switch can usually be cleaned easily, to restore its function. And proper quality switches can be actuated millions of times before failure.

> A mechanical switch is easy and cheap to fix or replace.

Not if it is in an airplane. Think of all the QC steps required to track the production, storage, shipping, installation, testing, etcetera for the replacement of a single switch. If a switch has failed it needs to be inspected to understand the reason for failure (no switch should fail; tracked to understand if it is a batch failure, plus other steps). I am only making an educated guess here.

> A switch can usually be cleaned easily, to restore its function.

Ummm, you think they put known failed parts back in planes? I think not. They do fix major parts, but the QC for that would be insane. You would make a switch to be hermetic and add anti-tampering - a manufacturer of any safety related device doesn’t want it to be “fixed”. Items are designed to be maintained (with proper schedules), or replaced.

> And proper quality switches can be actuated millions of times before failure.

On average? Or does it have a bathtub curve? Yes, quality switches are insanely reliable, but so are touchscreens.

If you have a variety of 50 switches and knobs, then the reliability is worse than 50x worse, because every item has it’s own reliability curve, and it only takes one failure to muck up your day.

>Not if it is in an airplane.

Even less so if it's on the space station. Or on a Mars rover. But we're talking about cars. Something a lot of people like to mend for themselves.

OP context of this thread is touch panels in aeroplanes, not cars.

I can say that an intermittent switch failure is hard to diagnose and potentially costly. The dash on a 2007 Ford I got cheaply had an intermittent fault where the whole dash would shutdown, and headlights would go off, while driving. Switching ignition off and on would fix it, so I presumed it just needed a reset. It was actually the barrel switch of the key - intermittent enough to cause a lot of dangerous trouble but hard to diagnose.

Point of fact; A touch interface digitizer and the LCD screen are two separate components just often glued and sold as a single unit. Replacing a digitizer, or a screen should be no more difficult than swapping out an analog component with a proper modular physical layout and connectors.

A cheap phone or tablet hardly represent best of breed for the technology as a whole.

Another factor is having to keep a larger variety of inventory for mechanical switches, vs a single touch screen SKU standardized across many models.

What happens if an object impacts a touchscreen and it breaks? I have my screens break (even behind a screen protector) and has failed to respond to touch. Imagine you are flying a plane and the touchscreen breaks due to impact. All your inputs are centralized behind that one touchscreen and you can no longer operate it. Wouldn't it be then better if there were multiple points of failure? You are decentralizing the impact a failure can have. Sometimes having multiple points of failure is a good thing. That way a failure in one component won't affect the other components.

Have a spare screen that you can just slot in and carry on.

The airplane cockpits I've read about have multiple screens, with knobs selecting the function of each screen (and which of the redundant flight computers control each screen), so a failed screen can be replaced by selecting its function on another screen. This makes more sense (and is simpler) than carrying a replacement screen (which would be dead weight most of the time) and designing a hot-swap mechanism (which would be yet another potential point of failure).

While your plane is falling from the sky?

Anecdotaly, my touch screen devices's screens are less durable than my mechanical keyboard, but I agree with your overall points, touch screens can be made incredibly durable.

Very interesting... I wonder what it would take for a touchscreen keyboard to be as reliable or live as long as a mechanical keyboard. Maybe it already does, but my mental picture and experience of phone screens getting flaky, and taking secondary+ swipes does not give me the confidence a mechanical keyboard does.

If they can make a durable touchscreen keyboard with a good click sound and feel and reasonable key travel and resistance, and that doesn't get crudded up with skin oils and food film, I'm willing to pay big bucks for it.

Multiple physical knows will never fail all at once like a single touchscreen can. As a small plane pilot I prefer to have as many independent systems as possible; I use an iPad for instruments and navigation, but every single function is duplicated by a separate instrument, so if I lose the iPad for any reason I have the instruments in the cockpit. I had several incidents where single components failed, but I was able to safely land the plane every time. Hardware failures are as much as a problem as software failures and dual-redundant critical systems are far better than multi-functional devices.

The iPad touchscreen is very reliable until you splash water on it. I don't think splashing a cup of water onto 1995 car dashboard would trigger any of the buttons.