Comments by "Keit Hammleter" (@keithammleter3824) on "What you Didn’t Know about the Amazing DC-3!" video.

@flagmichael : In any case, if current flowed when the switch was on, current in a return wire would cancel the magnetic field from the hot wire and you would still have no effect on the compass.
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Mentour now said the magneto switches are in the up-high position so they can be seen by crew outside on the ground, so they know an engine cannot fire while they are manually swinging the props. That seems a good idea. But - Other piston engine airliners had the mag switches in the same place (eg DC6) or in other places (eg Ford Trimotor), and the switches are not easily seen by ground crew (in DC6, cabin too high and switches are tiny, Trimotor has mag switches below windows). But this pattern always seems to hold: Engine controls normally used during flight (eg throttles, mixtures, prop pitch) are grouped in one place and easy to hand, and any engine controls normally used on the ground (eg mag switches, generator switches) are grouped in a place well away from in-flight controls - and thus necessarily in a less convenient to hand place. In flight engine controls have distinctive shapes and also move forward/back, but controls used on the ground move left/right or up/down. That all seems very sensible - makes for an easy to fly aircraft - and very unlikely a pilot would accidentally, say, turn off magnetos when he meant to alter mixtures - which would be rather a nuisance and upset the passengers.
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