Why is it intuitive to have the up and down arrow keys reversed in flight simulation games?

Some examples include: Flight Simulator, Descent (technically a FPS game), Terminal Velocity.

I've tried reconfiguring the keys to make the up key move the view upwards, and the down key downwards. But this felt really unintuitive. I'm wondering if the reason for this is because I'm simply used to having the keys reversed, or if there's another reason why it feels intuitive to have the up and down keys reversed.

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    This isn't just flight sim games. Many FPS' have the option to "Invert y-axis" to give the same effect. – Raven Dreamer Mar 13 '11 at 22:08
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    You can learn to play with invert and with no invert and switch between one and the other in the matter of minutes. Although it's pretty awkward at the beginning. I was alway using inverted mouse for everything until I got cool game that didn't have invert. Then I mainly switched to not inverted. – Kamil Szot Mar 14 '11 at 1:23
  • FPS player here, learning to play flight sims. My brain is boiling from the inverted axis, and even more so from the X axis being roll and not yaw. For me, it is anything but 'intuitive'. I'm about to swap the axes, 'uninvert' Y, and see if I can fly better with veterans laughing at me ;) – Septagram Oct 26 '14 at 21:26

Here's my guess for how it feels to control a flying vehicle. Also, here are some bits of flight dynamic terminology.

Pretend you are sitting in a plane. Imagine the plane has a big imaginary stick poking out the top of it, and you are holding a flight stick whose position represents how you want the imaginary stick to move.

In that case, how would you make the plane go up? You would pull the stick backward, because that would make the plane tilt backward and its nose point upward.

To make the plane go left, you could yaw by twisting the flight stick... but I don't think real planes can do that altogether well, so instead you would tilt the stick left for roll and then pull back for upward pitch. [Edit: See comments, apparently planes can move this way just not super fast.]

But as for whether you are just used to controls this way, I think so. A whole lot of people prefer non-inverted Y axis controls in games. But as you and I both know, those people are crazy ;). Once you get used to controls like these for flight games, it makes sense that would translate to preferring inverted Y for FPS games as well - that's what happened with me and StarFox.

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    So you invert the mouse Y for FPS games as well? While inverted Y seems intuitive for me on flight games, it's quite hard to do the same with using the mouse. I prefer the regular Y directions for my deathmatch games. :p – Andrej Mitrović Mar 13 '11 at 22:50
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    Actually planes can yaw, they have rudders, but you are right, if you want to make a sharp turn, use the bank and pull up. – AttackingHobo Mar 13 '11 at 23:52
  • @Andrej I use inverted-Y for everything but the mouse, you're right that it's just unnatural. – Matthew Read Mar 14 '11 at 0:50
  • Yeah, I have always inverted the Y-axis on FPS games on the PC, since that's how I learned to play Quake. Oddly I don't do it on FPS games on consoles. – Alan B Jun 6 '12 at 7:31

Most possible is that's because of how the real plane controls are made. If you have ever played with a joystick, the default behavior for the plane/spaceship/etc is to lean downwards when you push the joystick ahead. It is made do be similar in general with real plane controls.

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    Kids nowadays, growing up playing Halo first instead of X-Wing vs TIE Fighter and whatnot :P – Matthew Read Mar 14 '11 at 0:52
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    Pfft! Kids nowadays, growing up playing X-Wing vs TIE Fighter without first playing X-Wing and TIE Fighter and what not! – Drew Mar 14 '11 at 9:04
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    @Shaderach Haha, indeed! I played Rebel Assault first myself, came out the same year as X-Wing. – Matthew Read Mar 14 '11 at 14:30
  • I hated the rails aspect of Rebel Assault. X-Wing and TIE Fighter though... man, what a great way to grow up! – Drew Mar 14 '11 at 22:03

While controlling up/down is clear in a 2D side-scroller, in 3D first-person-perspective games, you have the option of thinking of up/down controls in different ways:

  1. "Up is towards the top of the screen, down is towards the bottom." In this case, you think of the joystick as a symbolic representation of left/right/up/down. The joystick represents a direction.
  2. "To see up, I must tilt my head back. To see down, I tilt my head forward." In this case, you think of the joystick as mimicking the movements of your body. The joystick is a movement, not a direction.

This is just my theory, but seems reasonable. I liken it also to the concept in 2D top-down driving games where you can usually choose between the joystick representing directions on the screen (left will drive to the left of the screen, regardless of car direction), or the joystick representing the actions of the driver (left will turn the car left, which could be any direction relative to the screen).

Maybe there's some psychological inferences buried in there too, like cold-hearted people choose non-inverted-Y-axis. Or crazy people :P

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  • I agree with choice number two. You tilt your head forward to look down, tilt it back to look up. Inverting the Y axis allows you to mimic natural head movement. – Fara Mar 14 '11 at 2:14
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    If you follow the logic of your second option all the way through, you should invert the X axis too. – Cascabel Mar 14 '11 at 13:08
  • @Jefromi: "To see left, I tilt my head right"? That doesn't work in the X axis. Even if there is a way to explain it logically, it's not how we think of it, which is what matters. – tenfour Mar 14 '11 at 13:11
  • Well, the problem is that a mouse doesn't have the same degrees of freedom as the joystick. Ultimately, you're moving the mouse the same direction as the back of your head moves - up to tilt down... so left to rotate right. It sort of makes more sense if you think of the mouse plane as horizontal instead of vertical, so that it's mimicking the top of the joystick... except for the fact that to mimic the motion of the head, turning left should be a twist, not a tilt of the joystick. (I do still find inverted Y perfectly intuitive, just pointing out that our intuition here isn't perfect.) – Cascabel Mar 14 '11 at 13:31
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    @Jefromi Try thinking of it not mapping to the back of your head, but to the front of your head - like if a joystick were sticking out of your nose. If you were to rotate that to onto a horizontal plane and maintain the left-right direction, then the direction that corresponded to facing upwards becomes "back", while looking down becomes "forward". This mimicks using the Up Arrow to look down, and the Down Arrow to look up, as from the keyboard perspective Up is Forwards, and Down is Backwards. – Grace Note Mar 14 '11 at 16:26

There is a really good reason planes are controlled like this:

If pushing the stick forward (away from you) meant the plane flew upwards, your momentum would cause you to push even further forwards, making the plane pull harder, making you... etc.

By having the stick move the way it does now, things are a LOT easier to keep under control...

You know how hard it is to maintain a tight corner in a fast car? You have to strain to hold the wheel in place and not straighten out? Imagine the opposite! If you turned the wheel hard right to turn the car hard left, you'd EASILY wreck on even the most minor corners!

It's not just "intuitive", it's physics-based safety!

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  • I never thought of that! Nice answer. – Andrej Mitrović Mar 14 '11 at 15:32

Sandman, tenfour, and Mag Roader make good points about using a real plane's joystick and controlling the motion of the head, rather than the eyes.

You can also think about if you are walking in a busy space - say a busy workplace where many people must walk through a small confined space, but each must hurry to complete their tasks. If you've just finished carrying something to its destination and quickly turn around to walk back to where the rest of your load is, but there is someone who you didn't see or hear walking up behind where you were just standing, your immediate reflex is to pull back to not collide with them. If you were distracted in an airplane and suddenly realized that you were about to fly into an obstacle (other pilot, birds, projectiles, mountain, tree, ground) your reflex would inspire you to perform this same motion: "Pull back!". It makes sense, then, that aircraft controls would mirror this instinctive human response. You can even think of sitting in a cockpit and wanting to look down at what is in front of you, but moving underneath your field of view. In any other situation, you would want to lean forward to peek over the edge of your supporting platform, so leaning the joystick forward to look downward over the nose of the aircraft is also natural.

One thing that I think deserves to be drawn out is that we talk about 'Up' keys or 'Up' on a Directional-pad, but almost never do we actually position our keyboards or controllers/joypads so that the so-called 'up' cursor key actually points up. Usually, a keyboard lays flat on our desk and a controller lays face upwards in our hands, perhaps only slightly tipped back toward us. Taking this into account, once you've held an aircraft's joystick in your hand in real life, it is very easy to stop thinking of the 'Up' key as 'Up', and rather as 'Forward'. Likewise, the 'Down' key ceases to be 'Down' and becomes, simply, 'Back'. This is a small transformation in thinking, but actually usually more accurate to how we use our keyboards, joypads, and mice, than mentally translating their directional inputs 90 degrees in space.

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  • In your vision, the 'Up' key is at the top, though. – Ullallulloo Mar 14 '11 at 15:30
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    To my way of thinking, it is merely closer to the screen than I am, which is still 'Forward'. – Nate Lawrence Mar 14 '11 at 16:10

There used to be a really nice diagram that I saw a while back that explained it really well, but I'll attempt to recapture it's glory by typing it out.

Inverted controls are like moving a camera on a tripod. For example, imagine a camera on a tripod. In order to make the camera point upward, you tilt the stick downwards.

Normal controls make sense when you are instead trying to point at something, ie. move your finger up to point at something upwards.

So, in flight simulations, inverted controls make sense most of the time, since you are controlling the tilt of the plane rather than the direction.

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As someone who has spent 3+ decades in military aviation I can tell you this is Exactly the reason why. Push Forward = houses get bigger. Pull Back = houses get smaller. That's it. That control logic gets burned into peoples minds so deeply it's a reflex reaction.

It goes beyond that too. The smaller controls in an aircraft also have the same control logic, as do the sensors. I.E the electro-optic sensors. When you move their controls forward (joystick or ball) the camera view moves down. When you pull or roll it back, the camera view moves upwards.

This is actually the norm. The standard out in the real military world.

Since the advent of games being played by people at home, without any outside training, they get used to whatever feels natural to them at the time they begin playing. Unfortunatly for many, it's the wrong way (from the military perspective). I've seem more than one young person cuss and complain (to no avail) that the military equipment is "wrong" and they are "right". They get used ot it. Actually it's been that way since at least WW2 and I don't think it's going to change, at least in the military anyway. They un-learn their ways and fall in eventually. For me the feeling is just the opposite. I've been doing it that way for so long, when I sit down to play a video game where pushing forward commands up instead of down, it causes more than a bit of shock! It's just a game though, no one's life depended on it. ;-)

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