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Which way is "ON?"

claycookiemonster

claycookiemonster

Well Known Member
While light switches in homes are universally UP = ON, my aviation experience is not so conclusive.
Airline switches on the overhead were FORWARD = ON, and on the panel in front of us were generally UP = OFF.
Just reviewing my legacy USAF Dash Ones (T-38 and F-111) the panel switches seemed to be UP = OFF.

Is there a standard orientation in the GA world?
 
Well, sometimes it depends on whether they're rocker switches or toggle switches and how they're labeled (e.g., on the visible portion of the top of a rocker switch). But I would say most of us with standard toggle switches have up = on. It'll be interesting to see the debate on this one...:rolleyes:
 
claycookiemonster said:
While light switches in homes are universally UP = ON
Click to expand...

Not universally. I've found that a lot of European homes I've stayed in, as well as hotels, have DOWN = ON.

AC 20-175 is one starting point, maybe, who knows?

Table 1. Examples of Conventional Relationships between Control Functions and
Movements.

Function Direction of Movement

Increase Up, Right, Clockwise, Forward, Push-in, Depress
Decrease Down, Left, Counter-Clockwise, Rearward, Pull-out, Release

On Up, Right, Depress, Clockwise, Forward
Off Down, Left, Release, Counter-Clockwise, Rearward

Raise Up, Rearward, Pull-out
Lower Down, Forward, Push-in

Right Right, Clockwise
Left Left, Counter-Clockwise
Click to expand...
 
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Another question, if you mark the switch OFF, does it also need to be marked ON also?
 
claycookiemonster said:
While light switches in homes are universally UP = ON, my aviation experience is not so conclusive.
Airline switches on the overhead were FORWARD = ON, and on the panel in front of us were generally UP = OFF.
Just reviewing my legacy USAF Dash Ones (T-38 and F-111) the panel switches seemed to be UP = OFF.

Is there a standard orientation in the GA world?
Click to expand...

I worked on nearly every a/c in the USAF inventory in the 50's-'60's- don't remember ANY upside down switch below the windshield on any aircraft. Up is on. B737 sim the same. GA aircraft too. There must be some exceptions for some reason of course, but I don't recall any.
 
"On"

Webb said:
Another question, if you mark the switch OFF, does it also need to be marked ON also?
Click to expand...

I sure hope not or I need a bunch of "ON" labels. :D
Mine are all labeled with function on top and "OFF" at the bottom. Except for multifunction switches like the P-mags. Those are "OFF", "RUN", "TEST" in between the two switches. Control cables and the sticks are all labeled. Start button is also labeled.
 
In certified GA airplanes, traditionally up is on. If the switch is mounted laterally, then inboard is typically on.
 
Cumulo said:
I worked on nearly every a/c in the USAF inventory in the 50's-'60's- don't remember ANY upside down switch below the windshield on any aircraft. Up is on. B737 sim the same. GA aircraft too. There must be some exceptions for some reason of course, but I don't recall any.
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The 737 has a bunch of switches that are “down” for “on”.. the entire overhead panel. I guess as you sit in the seat, it’s really “forward” for on.
 
O/P here. On the MD-80, there were switches for the landing and taxi lights up on the glare shield, and down was on. Yes, any switches on the overhead were Forward is ON in the Boeing/ McDonnell world, but forward was actually a bit DOWN too.
As to the GA stuff. For the E-Mags, there are three position switches for each of them with OFF-ON-TEST functions. My mind can't get past the instinct that UP is OFF. The middle position will be ON, and down will be the temporary TEST position.
I suspect whichever way I do them will become the instinctive way to do them. I guess I'm asking what way the GA types will expect them to work.
 
AC 43-13 1B

Ac 43-13-1B covers this on page 11-19

On is upward or forward

When controlling moveable elements such as landing gear or flaps, the toggle should move in the same direction as desired motion.

I see I also pencilled in this….If movement is horizontal, right is on. (I must have added that from a classroom discussion with the instructor when in A&P school.). That’s how I mounted mine.
 
Replying to Desert Rat who says in the case of laterally operating switches, "Central" is equal to ON. I think this breaks a code for me.

In the case of overhead switches, Down is ON. From the position of being in the overhead, Down is also "Central. I noted a few switches which were placed low in the 737 (like footwell lights) and on those low mounted switches, Up was both ON and Central.

Might it be that pulling a switch more into alignment with our vision which is generally "Central" feels like ON to the brain? Pulling UP on a low mounted switch feels like pulling down on a high mounted switch? A switch mounted significantly Left or Right of center is ON when pulled to the Central position because that's where our eyes are looking? Those glareshield light switches on the MD-80 were relatively high on the forward panel (though certainly below the eye line which was looking out the window) so they may have felt like the overhead switches where forward (down) was ON.

Something about this makes sense to me. Any cockpit designers out there comment on this?
 
Most crew station work I've done was on military aircraft, and for them the relevant spec is:

MIL-STD-203G, MILITARY STANDARD: AIRCREW STATION CONTROLS AND DISPLAYS: LOCATION, ARRANGEMENT AND ACTUATION OF, FOR FIXED WING AIRCRAFT

available at http://everyspec.com/MIL-STD/MIL-STD-0100-0299/download.php?spec=MIL-STD-203G.009454.PDF

I think we can probably claim the RV-8 is a bit like a military aircraft. Certainly quite a few of them are painted that way. The relevant section is:

3.7 Control and switch actuation.

3.7.1 Position related. Direction of control movement or detent position
is in the direction of the resultant motion of the aircraft or associated
structural element being controlled.

3.7.2 Performance related. The direction of control movement that is:

(a) Forward, upward or clockwise. Forward, upward or clockwise,
resulting in increased performance of the component or aircraft. Conversely,
movement aftward, downward, or counterclockwise results in decreased
performance of the component or aircraft.

(1) For side console components. Outboard movement results in
increased performance and inboard movements results in decreased performance.

(b) Variable rotary. Clockwise from the “off” position through “low”
or "dim" to "high" or "bright" for controls of a variable nature induced by a
rotary motion. Operation counterclockwise shall reverse the induced condition.

As for housing electrical switches, when first I visited the USA I had lots of problems with the switches being reversed from "normal". In Australian houses, down=on.
 
claycookiemonster said:
While light switches in homes are universally UP = ON...
Click to expand...


Universally = universally in USA.

While I don't travel universally, I travel extensively and in all those countries I visit (including my own), up = off.

Is there a standard? I've not seen one published but with Cessna and Piper being so prevelent and influential they have set a standard of their own in the GA world. If building your own, surely whatever makes sense to you is probably best for the basic switches. As noted, things like undercarrige switches would always be best orientated in the direction of movement.
 
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RV7A Flyer said:
Not universally. I've found that a lot of European homes I've stayed in, as well as hotels, have DOWN = ON.
Click to expand...

Two-way switching in domestic lighting is pretty common now, so switches can be in either position for on or off. I presume it's the same in the US?

Two-way switching aside, generally for a rocker switch I assume down (i.e. pressed in at the bottom with the top edge showing) to be on. This may be because some toggle switches have a red colour or the word ON on the top edge, which is visible when in that position.

For a toggle switch I assume down to be off and up to be on, unless marked otherwise. Not sure why it is the reverse for toggles, but that's how it seems in my mind.
 
“up” is ON and “down” is OFF

With three aircraft documents (AC20-175, AC43-13, MIL-STD-203G) all stating that “up” is ON and “down” is OFF, that sounds like a standard to me but it seems like even the big companies don’t follow standards. But this is experimental so do what ever you want but if someone else is flying it, or if you sell, it maybe confusing to others.
 
claycookiemonster said:
Replying to Desert Rat who says in the case of laterally operating switches, "Central" is equal to ON. I think this breaks a code for me.

In the case of overhead switches, Down is ON. From the position of being in the overhead, Down is also "Central. I noted a few switches which were placed low in the 737 (like footwell lights) and on those low mounted switches, Up was both ON and Central.

Might it be that pulling a switch more into alignment with our vision which is generally "Central" feels like ON to the brain? Pulling UP on a low mounted switch feels like pulling down on a high mounted switch? A switch mounted significantly Left or Right of center is ON when pulled to the Central position because that's where our eyes are looking? Those glareshield light switches on the MD-80 were relatively high on the forward panel (though certainly below the eye line which was looking out the window) so they may have felt like the overhead switches where forward (down) was ON.

Something about this makes sense to me. Any cockpit designers out there comment on this?
Click to expand...

Hi Clay, I said inboard (central) but what a really should have said was forward.

You know how you roll up to a stop light and when you get the green arrow, it points straight up? Sadly you can't drive straight up when it turns green, but in that case our brains associate up with straight forward since thats the closest thing to what we're seeing.

Likewise, To the best of my knowledge, nobody has ever made an airplane where you pulled back the black knob to make it go faster, because our brains are wired so that pushing that thing forward just makes sense.

For simple toggles or rockers, the primary "ON" function should be activated by pushing the switch toward the front of the airplane, just like you do with the throttle levers.

Depending on where they are and how they're oriented, your brain will typically associate this with up for vertically mounted switches in the panel, forward for switches that are in a pedestal, or side panel, down for switches that are in the overhead, and toward the center of the airplane for switches that are mounted horizontally and can only move left or right.

I'm sure that there are exceptions to this just like there are for everything, but by and large, if you follow this outline, anybody that gets in your plane will intuitively know how to turn stuff off and on
 
Desert Rat said:
I'm sure that there are exceptions to this just like there are for everything, but by and large, if you follow this outline, anybody that gets in your plane will intuitively know how to turn stuff off and on
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Agree wholeheartedly. Trouble is, this is EAB, so there is always someone who makes the "It's mine and I'll wash it as much as I want" argument ;)
 
We had a cream puff Cessna 120 come into the MX shop I was working at and needed a post-MX test flight afterwards so I volunteered. All of the switches were “up for off” which I thought was pretty weird but manageable. When I took off the nose started rising so I rolled in some “down trim” and it started rising even more! I never bothered to research this but was told there was a couple of years where this was the standard at Cessna. Hard to believe but anything is possible.
 
As to home switches being universally anything, I lived in the UK for a few years, so that broke the universality of UP being ON. Living there also broke the universality of which side of the road to drive on.

Also, now that more and more lights in homes have two or more switches on distant walls, the UP = ON standard is over. Now, if you go to the switch on the wall of your home to make the light do something, either ON or OFF, you simply move the switch in the other direction, whichever way that is.
 
Planecrazy232 said:
We tell our novice electricians if the switch says “no” it’s upside down…
Click to expand...

That’s hilarious.


Comparing home light switches, where you can immediately see the result, is a poor comparison. You can’t see the result on many of our aircraft switch functions, like strobes, fuel pump, etc….

I had a manufacturer design a slide dimmer that went left to right, dim to bright, with a triangle shaped switch. It failed to sell. Don’t go against convention.

“UP” is “ON” , unless it’s a push button like a resettable button breaker, then, “IN” is “ON”, just like an overhead switch is “ON” when forward.

These are simple conventions.
I am surprised there is any discussion about it.
 
Folks have cited several good reference documents that give concrete design criteria to make cockpits consistent. Yes, its your homebuilt, and if you want to make the controls reversed, that’s your prerogative, but as someone who frequently hops in new airplanes to test them, I’d suggest that there are better places to invest your creativity - I have had , on more than one occasion, a frustrating surprise with someone’s “original idea”. Are there exceptions out there in the world? Sure….that doesn’t make them a good idea in general!

Back when I was laying out the panel in my RV-8, I enlisted commentary from my buddies, the top test pilot graduates of our nation’s test pilot schools. The topic was “IFR Navigator/radio on the right, or on the left?” The responses could be categorized as such:

Naval Aviators: “You should never take your hand off the stick, you could be bounced at any time and need to maneuver - tune the radio with your left hand!”

Air Force Pilots: “You should be competent enough to fly with either hand, and you can always engage the autopilot if you can’t - tune the radio with your dominant hand, put it on the right!”

Army pilots: “The radio should be where god intended it - underneath the wicker seat the pilot sits in!!”

Paul
 
sailvi767 said:
To keep things confusing Airbus will do it either way. Some airlines had a mix of both.
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Yep, Boeing did (or still does?) the same depending on the customer.

Years ago I was a B727 flight engineer at a charter/freight outfit with a ragtag fleet of ships from American, Pan Am, Eastern, Delta, etc. All had standard Boeing “forward is on” switchology. Then there were the 2-3 ships from TWA; switches reversed… weird.
 
Several responding have airline and/or military experience. Despite recommended standards, the standard is that there is no standard.

Those of us who have flown multiple types at out day jobs throughout our careers have experienced Go Around and Autothrottle Disconnect switches in various positions on the thrust levers.

Those are some really hard habit patterns to break. If ever there was a need for a standard, that would be it. But we train and adapt. And sometimes in the "hot seat" you can feel muscle memory from three planes ago weighing heavily.
 
Which way is "obvious?"

There is an urban legend within the F-111 community regarding the first installation of a wing sweep control. Since there was no established, or even blindingly obvious way to make a control that would make a wing move. the GD engineers (General Dynamics, though the other version applies as well) decided that a handle should slide fore and aft below the canopy rail on the Pilot (left side) of the cockpit. Sliding handle equals sweeping wings. Fine so far. But, which way is the obvious way to connect handle to wing?

Those GD engineers noticed that pushing the throttles forward meant going fast, so they thought the wing sweep handle should also be pushed forward when the aircraft went fast. Throttles forward and wing control forward equals FAST. Reasonable.

Now, fast forward to a pre-production F-111 doing a bit of an airshow for some interested parties. The pilot wanted to do a slow speed pass for those watching and not being a GD engineer, he did the pilot thing. Throttles back to slow and wing sweep control forward to make the wings go forward.

The wings obediently swept full aft, since he had pushed the control forward, indicating his desire to go FAST. The aircraft ran out of lift with throttles aft and wings swept full aft and it landed short in the overrun and slid down the runway.

The wing sweep control logic was reversed. The sliding handle went in the direction you wanted the wings to go.

Final Score: Pilots: 1, GD Engineers 0.
 
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claycookiemonster said:
Also, now that more and more lights in homes have two or more switches on distant walls, the UP = ON standard is over.
Click to expand...

3-way (or more) lighting circuits have been around forever in homes. Not a new thing, and a bit outside of the scope of aircraft switches, I think. :)
 
Up is On, please

I fly a friend’s Cessna 140 sometimes and all the switches are backwards, that is, up is off. As a general aviation pilot and A&P I have to look at the switch before I move it and think about it because it’s backwards to everything else I’ve ever flown. Or worked on, pretty much mostly, for that matter. My first A&P mentor tells the story about hand propping a Champ with toggle switches controlling the magnetos. His headset was hanging on the tube above the instrument panel and guess what happened? Yup, he moved the prop and it started. Scared the whee out of him even though he was using good technique and staying out of the propeller arc. Yup, the headset fell down and turned a magneto on because… down was on. And so I’ve always installed switches so up is on, except on my friend’s 140 because that’s how the original placards read. I don’t like it, but there ya are, I guess. But yeah, my vote is down is off, up is on. My airplanes are that way and ever shall be.
 
Towards windscreen

On my first Boeing type rating the instructor simply said “on is towards the windscreen”. So panels below the windscreen switches go up for on, panels above switches go forward for on.
 
Ray Cote was a Reno Champion for many years and had his mag switches reversed so that up is off and down was on. Claimed that the G forces when they were installed properly would sometimes shut off his mags so he reversed them. Sounded like a pretty far fetched explanation to me but that’s the beauty of the experimental world, you can do what you want.
 
rmarshall234 said:
Ray Cote was a Reno Champion for many years and had his mag switches reversed so that up is off and down was on. Claimed that the G forces when they were installed properly would sometimes shut off his mags so he reversed them. Sounded like a pretty far fetched explanation to me but that’s the beauty of the experimental world, you can do what you want.
Click to expand...

If, like a lot of homebuilders, he was using recycled parts to keep costs down when he built his racer, he may have had some old clapped-out loose switches and there may have been something to that... :)
 
"...Likewise, To the best of my knowledge, nobody has ever made an airplane where you pulled back the black knob to make it go faster, because our brains are wired so that pushing that thing forward just makes sense..."

Yet most of the aerospace ground support equipment (AGE) I have run across has a "backwards" throttle... Push for low RPM, pull for high.
 
Toobuilder said:
"...Likewise, To the best of my knowledge, nobody has ever made an airplane where you pulled back the black knob to make it go faster, because our brains are wired so that pushing that thing forward just makes sense..."

Yet most of the aerospace ground support equipment (AGE) I have run across has a "backwards" throttle... Push for low RPM, pull for high.
Click to expand...

A coworker had an absolutely hilarious story about a summer job in high school working at a dairy. Tasked with using a powered pallet jack type of "GSE" to move a bunch of large containers full of milk, she didn't know that pulling on the handles made it go faster. So she pulled, it went faster, she pulled more thinking to slow it down, it went faster still, pull, faster...until she and it were tear-assing across the lot before it ran full on into a wall, with predictable results to the large containers.

For aero GSE, it might be a safety thing...if you fall forward, the device slows or stops. If you fall backwards, let go and it stops. Maybe, I dunno. Could just be "the way its always been" with GSE.
 
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