Why are switches upside down ?

[Three Blades]

A Friday lunchtime question here...

Why do the majority of switches in (light) aircraft operate in reverse to most other switches you find in life ?
Most toggle upwards to switch on whereas all domestic and automotive switches are down for on.

[rustle]

I think you might find the light switches in American homes also go up for on... (There's a clue there somewhere ;))

[Kyprianos Biris]

A Friday lunchtime question here...
Why do the majority of switches in (light) aircraft operate in reverse to most other switches you find in life ?
Most toggle upwards to switch on whereas all domestic and automotive switches are down for on.

In case of an emergency it's slightly easier to switch off downwards I guess.

[shortstripper]

I think it dates back to early hand swinging days where "thumbs up" for "contact" led to switches being up to signify the same.

SS

[TheOddOne]

Nope, Rustle's right, I'm afraid...

PA28 switches make more sense, though - they're the rocker type, and much better laid out than Mr Cessna's offering.

TOO

[Three Blades]

Rustle, thanks, I had a nasty feeling that could be the answer !
At least all manufacturers follow the same route (unlike helicopter rotor direction).

[collectivefriction]

I would say it's old UK light switches which are upside down.

Along with UK power switches, oh and the power switches on the psu's of computers, external tape and disk drives (mostly US made) and pretty much any other rocker switch that isn't in a US house...

[Gertrude the Wombat]

In the 1970s lab equipment mains switches in the UK were changing from up being off to up being on ... so in yer average lab half of them were one way and half the other.

At the time we had the theory that for potentially "interesting" pieces of equipment the safe position was "off" and if you flail your hand towards the control panel in a panic it's easier to sweep your hand downwards and turn the mains off than carefully find the right switch and pull it up. We didn't actually know though (and aren't all mains switches now software controlled pushbuttons anyway?).

[Mike Cross]

Rustle has it.

Since powered flight was invented by the two bicycle makers from Dayton they got to choose.

It's also why the markings on taxiways are yellow and the taxiway edge lighting is blue, why we're left hand drive, why the rule is keep right when approaching head-on and why the ICAO date format is YYMMDD. (perhaps)

[bcfc]

I thought the date format YYMMDD is so that its easy to sort. I always use this format for date sensitive files so that when I sort, they're in chronological order. The US uses MMDDYY

[Final 3 Greens]

why we're left hand drive, why the rule is keep right when approaching head-on

So why were ships using these conventions? Some prosaic premonition?

[Mike Cross]

That's why I added the (perhaps)

You're quite right about the keep right rule.

However the left hand side is the natural side for the pilot's seat to be put in a nation that drives on the right, US roads have yellow markings and any edge reflectors are blue, and of course all of their household switches are up for on.

Interestingly the convention in UK newspapers is to use the date format MMDDYY (this morning's says Saturday September 16 2006)

The US format is normally MMDDYY so I guess bcfc probably has the right answer.

[shortstripper]

There was an interesting article in one of the flying mags recently discussing the left hand side thing. It reckoned that it came about from the fact that early RFC pilots being ex-calvarymen were used to mounting their steeds from the left as was the tradition. This habit transferred to fighter aicraft and the habit stuck that the pilot always entered from the left ... once side by side aircraft came along the habit just continued.

I prefer this idea as I don't see why everything should be american led? Early aircraft design and traditions do not owe all to the USA, as their developement ran at similar rates over here (they were not always the leaders in aviation). For one example, why do all single seaters not have the stick in the left hand as would be the natural way for a left hand side car drivers? Also the English could be said to have led the way in affordable GA with designs such as the Tigermoth that captured the market until much later when Cessnas and Pipers started being mass produced.

We owe a lot to the USA when it comes to aviation .... but NOT EVERYTHING :=

SS

PS .... and I still think I'm right about the "thumbs up / switches up for contact" thing :p

[Croqueteer]

:) Nothing so complicated. It started with mag switches which are "on" in the down position, ie providing an earth on the mag, and in the up "off" position the mags are now live. I presume to keep it simple, all other aircraft switches were then made up on.

[ComJam]

Final 3 greens makes a good point. The rules of the air came, not unreasonably from the rules of the sea.

[stillin1]

Down is off!
I thought it was so that when you did a really bad "thumper" of a landing the aircraft turned itself off to save further damage.
Ingenious really:E

[B2N2]

Here's a slightly stupid explanation;
"UP" for going into the air, "DOWN" for being on the ground.
Makes it easier to remember......:O
It makes sense if you think of a common standard applied by all manufacturers,
forward on a control is GO, back is STOP eg throttle and mixture.
Overhead swithes are switched on by moving them forward (in the direction of flight) and switched off the other by moving them back (away from the direction of flight).
This is all assuming you can keep the right side up and the pointy end in front...:}



Ok Ok I'll get my coat......

[Talkdownman]

forward on a control is GO, back is STOP eg throttle and mixture etcIt is a pity that such a convention cannot also be adopted for automatic transmission selectors in motor cars. I've lost count of the number of times I have got out of an aeroplane or a boat, got into my automatic BMW then selected reverse to go forward and forward to reverse.............:confused: The least the motor manufacturers can do for pilots and seafarers is PRND from back to front / aft to for'd / stern to bow, and not the other way round!

[Sleeve Wing]

Its not so long back that switches were considered "ON" when pointing to the glareshield !
That meant switches on or below the instrument panel would be "up" for "ON" and switches in the overhead panel were "forward" (down!)

The use of the word "glareshield" should be a clue as to the source of that idea !

Sleeve.

[Milt]

Croqueteer

You are correct. It all goes back to those early days when the only electrical switches were those to disable the magnetos. The first fitting was in England where the 'electrician' fitted the switches in the conventional sense of down for ON. The magnetos then became live with the switches in the UP (OFF) position. Had the first switches been fitted in the USA we would probably now have the opposite convention.

A world wide convention developed amongst the Flight Testing community a few years after WW2 whereby all aircraft cockpits'/flight decks' switchery and control levers should wherever possible be in the UP or FOREWARD positions for Take Off.

It would be of interest to hear of modern exceptions to the convention and whether it has been enshrined in design rules/regulations.

[collectivefriction]

Maybe I should have been more explicit but there's no need to jump down my throat.

I was not jumping down your throat just making an althernative point to your views in your previous post - this is a discussion forum after all, if you are not prepared to discuss then grow up and post elsewhere.

You may consider this post jumping down your throat if you wish :)