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In most cockpits, you'll find the full gamut of switch types in use. Toggle, rocker, push-button and more. Each has their own "feel" and might be used for different situations.

Is there any convention for what type of switch is used in a cockpit, and where/for what?

Such as, is the Generator usually/always a toggle switch, and would it be "weird" or unexpected for it be a rocker switch instead? Everything could be a toggle switch, so why do manufacturers choose to use different types of switches for different things?

The 737's overhead panel uses toggle, rocker, push-button, and rotary dial all together:

These images are from a simulator, but the aircraft is modeled after the TBM 850. In it, you'll notice toggle, rocker and push-button switches:

Same thing up top in the same aircraft:

Here's a real image showing the same thing:

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  • $\begingroup$ Are you asking if there is a specific regulation or design standard for what type of switch needs to be used for a certain function? $\endgroup$ – Ron Beyer Jan 12 '17 at 21:35
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    $\begingroup$ Air Disasters tv show - 737 crashes in Panama due to ADI gyro failure. The pilots tried to "make the ADI look right" but the gyro was intermittently failing. The gyro source selector is different from the simulator the pilots train in: "switch" vs "selector knob" - but in both cases the switch is turned/thrown left. And the gyro source selected is different. So how does "similar but different" factor in especially during a high-stress situation? And clearly standardized switch(ology) can kill you if it helps you forget about what's going on behind the switch. $\endgroup$ – radarbob Jan 13 '17 at 14:32
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    $\begingroup$ In C-130B models there was a "killer switch" which caused many a check ride failure, especially for those used to newer models. Selecting a nav-aid exactly like other C130 models did not feed that info to your instruments. You had to throw "the killer switch" to select for instrument display. And of course the killer was on the center console out of the cross-check view of both pilots. $\endgroup$ – radarbob Jan 13 '17 at 14:38
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    $\begingroup$ A gambit is a tactic where you deceive your opponent with bait or misdirection and then attack from the sides or elsewhere. A gamut is the full range of something. It comes from an early musical scale where the lowest note was called gamma and the highest called ut. $\endgroup$ – Todd Wilcox Jan 13 '17 at 14:51
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    $\begingroup$ This is an excellent question! Some things are obvious - Window Heat is on or off, so a simple toggle makes sense; but then, so does a rocker; but wait, a 2-position rotary will do quite nicely as well, thank you; a push-button will work; as will a momentary contact. Wait, I know, we'll use a touch screen! Yeah, I can see where having a standard convention, especially in the GA world where pilots are more likely to switch planes, would make a lot of sense. $\endgroup$ – FreeMan Jan 13 '17 at 19:15
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I can't give you a 100% correct answer, but I'll try as best as I can, having some experience with much smaller aircraft (even than the TBM850):

As far as I know, there are no strict conventions for this and this is why you see most aircraft types equipped with their own panels and cockpit design.

You always have to keep in mind that aircraft manufacturers put most of their engineering efforts into designing aircraft concepts for a specific market and then casting their ideas into an actual airframe that fits all the systems that are needed to operate the aircraft.

Allmost everything else (engines, landing gear, avionics, A/C, lights, APU, steering, braking and anti-skid systems etc.) is developed and manufactured by external suppliers with the aircraft manufacturer responsible for adapting and orchestrating all the systems.

This might lead to the aircraft manufacturer simply using already available switch assemblies or only slightly modifying the suppliers' reference designs for panels in the actual aircraft.

IMHO, this is easily recognizable when looking at the cockpits of (especially older) aircraft where there was no concept of the cockpit as a whole. Whatever switch assembly was needed was just somehow installed into the panels.

As Boeing's 707 was a great success, its cockpit design (at least partly) found its way into the 707s successors/derivates/siblings 727 and 737. This lead to the 707 setting the cockpit design paradigms for following (Boeing) aircraft.

Also, from a pilot's point of view, there are some semantic aspects about choosing a switch that 'feels right'. For example:

  • push-buttons to start an automated process
  • korry-type switches for switching automatic systems on or off or for on-off switches that might be controlled automatically (And therefor show their status; Airbus uses these a lot due to their cockpit philosophy)
  • toggle switches for everything that needs an on-off type switch on low-level without other systems needing access to it (for critical switches with safety cap as seen in the 737 overhead panel)
  • rotary switches for mode selectors
  • potentiometers for everything that is finely controlled by the pilot
  • rockers maybe for mode selection between two modes where neither of both is just "off"

are very intuitive to me. This might be training or just experiences from everyday life, but I understand what they are doing even before having read the manuals thoroughly, which makes it easier to remember which switch does what.

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Is there a convention for type of switch used and where?

Not in any strictly followed cross-industry way.

enter image description here enter image description here
Brand X vs Brand Y airliner

Even if two aircraft both use a similar toggle switch for something, they can disagree about which direction is on or off

enter image description here enter image description here

Note also that brand Y has different toggle shapes for three-position switches but brand X doesn't.

As jxe's answer says, within a single cockpit there is a lot more consistency.

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  • $\begingroup$ Your bottom two images illustrate a problem I encountered while flying for 2 747-100/200 carriers using aircraft from other airlines. For purposes of illustration, let's say the left image came from the overhead panel of any carrier except TWA and that the right image came from the overhead panel of a TWA 747. The overhead panel was angled, but TWA chose to think of it as a vertical pane insofar as the switches while all other carriers chose to think of it as a horizontal panel. Thus, for the left image the beacon switch is 'forward' for on while on the right the beacon is 'up' for on. $\endgroup$ – Terry Oct 29 '17 at 23:38
  • $\begingroup$ As @Terry states, Boeing offered airlines the special option to flip the switches "upside down". Lufthansa came up with this idea allegedly, and TWA followed. The TWA birds got flipped back when AA bought them, but AFAIK LH still has them today. Otherwise the convention is consistently aft for on. $\endgroup$ – user71659 Oct 30 '17 at 3:42
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Check document CS-25 (and CS-23) for "certification specifications, including airworthiness codes and acceptable means of compliance, for large aeroplanes" .

It details all requirements for required indicators, switches and CRTs on large commercial aircraft (23 for not-so-large-aircraft), including the shape of the landing gear lever (must resemble a wheel) and flaps lever (must resemble a flaps),etc.

Goto 'Subpart F - Equipment' and 'Book 2 - Subpart F'. Also check 'Book 2 - General AMCs' for more detailed requirments on the EFISs

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