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For a layman like myself, the cockpit of every single modern airplane that I've laid my eyes on seems like a complex, intimidating mess with knobs, buttons, screens and levers literally covering every single square centimeter. Every time when seeing this, from my point of view, chaos of control surfaces and indicators, I'm always thinking to myself "This HAS to be possible to make easier!"

Maybe my intuition is correct. Maybe it isn't. Anyhow, I can see a lot of possible reasons why one actually would want cockpits to be designed in this way. Maybe it makes it harder for an amateur to just wing it (no pun intended) and make it looks like (s)he knows what (s)he's doing. Maybe it forces the pilot to really understand every single nuance of the plane and its operation before even being able to begin taxiing. Maybe it fosters speed and security in an emergency situation by having everything accessible right away, accessible through muscle memory on the part of the pilot.

Or maybe most cockpit designers just are snobbish assholes who like to make the operation of aircraft a pain in the behind for everybody else. I don't know.

What's the design philosophy behind the design of the cockpit controls?

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I don't think your "snobbish designers" theory holds water. They're doing everything they can to simplify the cockpit, and they're making good progress. Remember when airliners used to require flight engineers, sometimes more than one? Now it's next to unheard-of. And the newest generation of small jets are usually single-pilot certified! –  dvnrrs Mar 29 at 15:56
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@dvnrrs Me neither. It was, what you humans normally refers to as, a joke :) –  Speldosa Mar 29 at 15:59
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I would say muscle memory has a big part. I've gone entire flights without reading the labels of the buttons I'm pushing. –  Steve V. Mar 29 at 18:16
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@SteveV. yeah, feeling that much safer now, thanks :-) –  yankeekilo Mar 29 at 21:29
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"An aircraft's panel should be as simple as possible, but not simpler." –  voretaq7 Mar 29 at 22:08

10 Answers 10

up vote 58 down vote accepted

I would argue that the controls of an aircraft are not complicated, but rather that they are simply foreign to you.

In the vast majority of cases, the various controls in the aircraft do one thing: Turn something on, or turn it off. They are quite simple actually, but what makes it appear complicated to you is that there are so many of them. As you learn about the airplane (especially modern ones) you will see that these individual controls are grouped together by system, in a way that actually makes pretty good sense.


To put it in perspective, let's say that you had never seen a laptop computer before:

laptop

This... thing (remember, you've never seen one before!) has 94 buttons on the top alone! It has all kinds of little jacks and plugs on the outside. It has things that pop open from the side. It's just... complicated.

Then someone points out that most of the buttons on the top are buttons that you can press to make a letter show up on the screen. This takes much of the mystery out of the complicated mess on the top, but then as you start to learn more you figure out that some of the less commonly keys are grouped together by function. You have the arrow keys, the function keys, the key modifiers, the CD controls... Suddenly it doesn't seem quite so complicated anymore.

You complain to your friend that the monitor (hey, we've learned a fancy new word!) is a little too small, and they suggest that you hook up an external monitor. We can do that?? Of course, that's what this port is for. Cool, now that's one less mystery. This goes on, and before long you can even pick up a different brand of laptop, with different buttons and pretty much figure it out on your own. Before long... the mystery is gone and it's just a laptop computer.


And so it goes with airplanes. Newer airplanes are being designed with fewer switches and gauges. Take a look at the progression in the Falcon 900 series aircraft:

Falcon 900B
Falcon 900B

Falcon 900EX Falcon 900EX

Falcon 900EZ Falcon 900EX-EASy

Each iteration has fewer and fewer controls and instruments. You may even say that they look less complicated. However, I can assure you that each newer model has far more capabilities and a lot more to learn in order to understand and safely fly the airplane. They each have the full capability of the model before it, along with additional features and more to learn. Certain systems no longer have switches or dials and you have to look through different menus in order to access them.

Appearances... can be deceiving.

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Something worth noting is that as each design iteration gets "simpler" the information desnity on the displays increases. Counter-intuitively it tends to take more training to successfully take advantage of increased information density, but once you have the necessary training there are substantial gains in efficiency (and theoretically safety). –  voretaq7 Mar 30 at 22:56
    
Worth mentioning is that the 900EX-EASy seems to be a somewhat experimental design. I'm not sure if I like it or not; on the one hand, there's less instrument clutter, but on the other hand, while it's true you mostly don't need e.g. engine pressure gauges, when you do need them, you tend to need them in a hurry. I'm not even an amateur pilot, though, so it may be I don't have a useful perspective on the matter. Also, where are the fire handles? –  Aaron Miller Mar 31 at 11:32
    
(Also, it occurs to me that you've underplayed your hand by omitting mention of the now-bygone flight engineer position, and the sort of complexity it entailed -- amply exemplified, I think, by this shot of the Concorde cockpit's flight engineer console. Someone who finds today's cockpits overly complex might do well to look back a few decades and see how things have improved since his parents' day.) –  Aaron Miller Mar 31 at 11:36
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@Kheldar Kind of. The one button iPad does still have many of the same functions (not all of them), but it is more complicated to find and use them since you have to know which app to start, or which settings to change in order to do something that a hardware button on the laptop does. So while it appears easier to use, if you are trying to accomplish a specific task (like say change the volume) it is much harder to accomplish without specialized knowledge. Even the keyboard is still there (on screen)... Once you figure out how to access it! –  Lnafziger Mar 31 at 14:05
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@Chris It's the underscores. I believe this is the one: geograph.org.uk/photo/1357498 –  Michael Kjörling Apr 1 at 9:29

99% of the information provided by all of those gauges, and 90% of the possible positions of all of those controls, are not necessary on a typical flight. You CAN take off, fly, and land, with just the instruments used on an ultralight (or less, if you think about the paramotor folks). But if anything goes wrong, or to squeak out a tiny bit more efficiency, you will want at least some of that extra info and extra control, and you don't know which things you'll need until something goes wrong, so everything is provided.

Analogously, many people who soup up street cars to race them will install many additional gauges and controls, which normal drivers don't want or need. Temperature monitors for specific parts of the car, toggles for different valves and sensors, etc.

ultralight plane gauge cluster pod

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It is not only "if anything goes wrong". In an airliner you need all the basic instruments plus the instruments necessary for IFR, the autopilot (not optional when you flight at high altitude), the engine management system, fuel gauges plus sensors and pumps, the ventilation/pressurization controls, radio + backup system for communications, navigation computer/instruments, control of all the electrics of the plane. Without any of those a commercial airline would be in an emergency. –  Martin Argerami Mar 30 at 18:32
    
@MartinArgerami but you still can fly without most of them. –  Ruslan Apr 1 at 12:26
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It depends on what you mean by "fly". Keeping it in the air for a little while, yes; performing the usual operations it is designed for, no. –  Martin Argerami Apr 1 at 13:19

The controls of an airplane don't have to be complicated. Here is a typical modern glider control panel:

enter image description here

These instruments are:

  • (top left) Variometer (shows relative climb/sink, only really useful for gliders)
  • (top centre) Airspeed (required)
  • (top right) Another variometer (in this airplane, one is mechanical and one is electronic)
  • (bottom left) Altimeter (required)
  • (centre) Compass (required)
  • (bottom centre) Temperature
  • (bottom right) VHF Radio controls

The instruments labeled (required) above are the minimum necessary for any aircraft. The controls not shown in this picture are:

  • Control stick
  • Rudder pedals
  • Airbrakes
  • Landing wheel lever

Now, gliders don't typically have engines, cabin pressurisation systems, hydraulic controls, fuel pumps, autopilot, navigational systems (ILS, VOR, DME, etc), HF radio, PA system, fire suppression, and so on. In particular, a modern jet engine (just the engine) is tremendously complicated and has many possible control inputs.

Unlike a road vehicle, if something goes wrong in an aircraft during flight the pilot can't just pull over to the side of the road and call for help (of even just get out and look in the engine compartment). The pilot needs full control over all the aircraft systems, directly from the cockpit, in order to be able to control the aircraft safely in case of an emergency.

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Only the legs are somewhat distracting - is that Australia Airlines? –  yankeekilo Mar 29 at 21:21
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The legs are part of the optional emergency ejection system. –  Greg Hewgill Mar 29 at 21:23
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I am not seeing any spider, so definitely not Australia Airlines. –  NothingsImpossible Mar 30 at 16:42
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"The man with one compass knows exactly what his heading is. The man with two is never sure." –  keshlam Mar 30 at 21:56
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The important difference between the variometers is that the left one is energy variometer (only used on gliders, indeed) while the right one is normal vertical speed indicator. They show very different information (and note that they are labelled in different units too). –  Jan Hudec Mar 31 at 4:45

As has been pointed out in a previous answer, the cockpit is a user interface. My belief is that it is virtually impossible to design any user interface that is user-friendly to both novice and experienced users, and I question whether you would really even want to do that. For example, in a light single engine aircraft with one fuel tank, a single on/off switch for fuel is understandable for the novice and adequate for the experienced. That same airplane might not have a hydraulic system so there is no need for hydraulic controls.

Now consider an airplane with nine fuel tanks, four hydraulic systems, and eight hydraulic pumps. Possibly you could engineer it such that when everything is working, a single on/off switch for fuel and another for hydraulics would work. However, if you're over an ocean with 400+ souls on board, you need more than everything is working fine or everything is not working fine. You need the ability to keep part of the systems working even when part of them have failed, and for that you need information on each component and the ability to control and/or isolate each component, not to mention understanding the components and how they work together, and how the failure of one can impact the failure of another.

It would be unreasonable to expect a novice to deal with failures of individual system components, and it would be irresponsible to put a novice in charge of such a situation. Thus, right off the bat, we can and should dispense with trying to make the system user-friendly to the novice.

So, we might have a system that seems incomprehensible to the novice, but it is and feels to be the right complexity to the person working with it on a daily basis.

The first airplane I regularly flew as a licensed pilot was a Cessna 150. It quickly became the right size. I decided one day I wanted to check out in a Cessna 172, and that airplane was a "big airplane" for the first flight or two. When I checked out in a 182, I had the complication of a propeller control and a manifold pressure gauge. Hmm, did I really need that? Through the years the airplanes got bigger, but I found that I came to regard the airplane that I was flying as just the right size and no more complicated than it needed be for the task at hand.

When they used a 747 to transport a single passenger, the movie star Rock Hudson, back to the U.S. when he collapsed in Paris, I didn't think that strange. It was just an airplane, and the 747 was that airplane that was the right size for me.

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There’s quite a difference in designing a user interface for a first-time user compared to an expert. Much of airplane design is only for experts, and the designers are willing to have a steep learning curve if it improves efficiency, ease, and safety once someone is experienced.

I’d also note:

  • Fewer controls doesn’t mean easier. In a car, for example, a touch-screen display can be much more annoying than a nice set of knobs.
  • Habits can be formed more easily with different kinds of controls and locations. Designers often deliberately make different controls look and feel different. You don’t want to confuse a gear knob and a flaps knob, for example, so they have different shapes. This can seem overly confusing at first, but really helps build muscle memory.
  • The location of the controls itself can be very significant. The knobs and switches on the ceiling are likely to be less commonly-used and thus don’t need to be in the direct line of sight.
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As others have pointed out, you can have a pretty simple instrument panel if you go with the bare minimum required instruments on the simplest possible aircraft.

I suspect you're more interested in aircraft with panels like like this one though:
Sport Cruiser panel

When we think about these aircraft you're actually seeing the "simplified" version - or at least the standardized version.

On the pilot's (left) side, there are six standard flight instruments: an airspeed indicator, an artificial horizon, and an altimeter on the top row, and a turn coordinator, directional gyro, and vertical speed indicator on the bottom. These six instruments in this layout are "the standard six-pack", and without going into what each one does it should suffice to say that they're the instruments a pilot is going to refer to most in flight, so the designers put them right in front of the pilot.
On the bottom of the pilot's side panel are switches for things like the interior and exterior lights, and a key-switch for the ignition (this particular aircraft has about 10 switches - they're all labelled, though you can't read the labels in this picture).

On the co-pilot's (right) side are a bunch more gauges which all have to do with the operation of the engine (the equivalent of the fuel gauge, oil pressure, coolant temperature, and tachometer in a sports car), and two rows of circuit breakers (unlike in a car where the fuse box is hidden away in an aircraft you may need to reset a breaker or replace a fuse in flight, so they're out and accessible - and like the switches they're all labeled).
Most of the time you'll only give this side of the panel an occasional glance during flight - since you don't need to look at this information all the time it's put off on the side "out of the way".

Down the center is the "radio stack" - a compass (up at the top) and a bunch of radios for navigation, communication, and ATC identification. Not "necessary", but helpful.
Between the seats you see a valve for controlling the fuel (the big red thing), and a throttle (the black lever between the seats).


While the panel may look intimidating at first the important thing is that it is fairly well standardized: you can jump into another airplane, look around for a few minutes, and know roughly where everything is and how to operate it. Even without much (any?) experience, you can probably find all the same instruments in roughly the same place in this slightly more robust panel - the biggest difference being that there are "control yokes" instead of sticks, and the addition of a few navigation radios and instruments. Even this DC-3 panel has a strong similarity to the first panel above, even though it's a much more complex aircraft. (The original DC-3 panel image is here - click through and check out the full-size version, you can read all the labels).

In that regard the layout of an aircraft panel is similar to a car's dashboard: You can drive in a Ford Mustang your whole life (the first panel), but if you sat down in a BMW 5-series the controls and instruments would be familiar to you (the second panel). If someone dropped you in a snow plow (the DC-3 panel) you may take a few minutes to look around and make sure you know where everything is, but you will be able to pick out the basic controls and gauges and know what they all do (which by no means implies you could handle driving the snow plow and more than I could handle flying a DC-3, simply that a lot of the knowledge transfers).


I've ignored "glass panel" aircraft in this discussion, but if you look at a bunch if them you'll find that they all have a similar layout (a large artificial horizon with "tapes" showing airspeed, altitude, and heading).

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A "glass cockpit" indeed hides a lot of secondary instruments (and maybe controls) that aren't needed all the time, but you still have the main instruments doing about the same thing in about the same place -- at all times. –  Phil Perry Mar 31 at 16:03

User interface design is complex. Incredibly complex. In a previous job, my company competed on the consumer market against an established company with an aerospace background. That was visible: their consumer products looked as complex as these cockpits. Ours didn't, because the lead designer was exceptional (think Apple-level UI genius). We learned quite a bit from the competition, understanding how that interface was hindering instead of helping.

Did that mean our product was simpler, could do less? No, in fact not. The main reason was that our UI was task-oriented instead of function-oriented.

If you look at the Falcon pictures above, you see a bit of that change. The classic cockpit is function-oriented. For everything that needs a control, there is a dial. And with lots of functions, there are lots of dials. Quite a few displays are duplicated because the equipment is duplicated. To take Terry's example, if you have 8 fuel tanks, there would be 8 gauges.

However, you often use those 8 fuel gauges together, rarely in isolation. For instance, the task "check fuel remaining" sums the results; the "check weight distribution" task focuses on the differences instead of the total. A task-oriented UI works better if it focuses on those tasks.

An additional benefit is that in combination with glass cockpits, you can pull up a big User Interface for the task at hand, since the same space can be reused for other tasks at other times. The classical sets of buttons and switches has a static layout and must share the available space.

As a case for this task-oriented UI, consider AF447. The pilots faced information overload, couldn't identify the task they needed to perform (recover from stall), nor the data they needed for that. Yet any pilot when quizzed could tell you how to recover from a stall, and the plane definitely knew it was in a stall.

Luckily there's hope. The use of checklists is well-established. They're closely tied to tasks. Not identical, some checklists bundle multiple tasks because they happen at the same phase of flight but not for the same reason. Still, the basic concept is that you execute a set of checks and actions which together achieve a single goal. That conceptual model, extended to all tasks should define the cockpit, not so much the physical hardware.

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Following in the line of reasoning presented by MSalters I would like to add a couple of points.

  • First of all there is no market pressure for the interfaces to become simple. With cars, boats and other vehicles 'normal' users with minimal training should be able to control them, thus car and boat manufacturers are motivated to make their product as simple as possible to understand. Some do this better than others, but comparing the middle dashboard of old cars with new cars there has been quite a change. In contrast with airplanes, put bluntly, it has already been accepted that a pilot needs a lot of training, so the strong pressure to simplify control and offload work to a computer (from function to task oriented) is simply not there.
  • Secondly aviation has to live with huge safety expectations. One of the results of this is - according to just a single expert I discussed this with... - that in the development of airplanes changing hardware/software on the control side is not done except if absolutely necessary. Why change something that's working? (even if it's as hole ridden as dutch cheese) And how can you change it if there is a huge checklist of things a human pilot is expected (legally) to do (regardless of a computer being better suited to the task).
  • And lastly, as pilots have received such exhaustive training it is even harder to innovate in the field, as people who have spend a lot of time on learning something are all the less likely to give it up. Thus making a plane which could be learned to pilot in half the time would be senseless as seniors would refuse to pilot it and juniors would still know how to pilot the old planes.

Oh well, just a few thoughts from the UX/market perspective.

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This sounds pretty similar to the (non-existent) evolution of some software, for example Microsoft Word and Microsoft Windows. Just look at the uproar that ensued after Microsoft decided to remove the start button in Windows 8. –  Speldosa Apr 2 at 13:12

1948 year train crash in Wädenswil (Switzerland) probably explains why "task-oriented interfaces" may actually be dangerous.

This train had the same control both to apply accelerate and decelerate with its electric engine, depending on the position of the separate switch. Indeed, you either accelerate or decelerate, never do both. Why to have two separate controls? A tiny switch looks enough.

Once, on a steep decline, the driver failed to select the right position of this switch and applied full power instead of braking. 21 killed. If it would have had two very different controls for brake and acceleration, such a mistake would have been much less probable.

So, where practical, it may be better to have more controls that never change they function and always do (or display) the same.

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There is not a single, uniform, design philosophy, for airplane cockpits. The cockpit is a "user interface". Some are easy to use. Others are powerful but confusing for beginners. Some implement standards so that knowledge of one can be applied with any. Some are hodgepodges with no consistency within themselves. Some start with an expresable goal but fail to acheave it. Some are utilitarian objects with controls and indicators in a regular pattern or patterns without regard for how they are comprehended or operated. In many cases, one intent at the beginning of design is merged with other ideals, requirements, informal norms and the like. Cheap and simple to build, and easy to maintain for decades, are as real as imperatives as any other.

In a modern Boeing transport, pilot and copilot each have a semicircular 'wheel' that turns left and right, to deflect the ailerons and regulate rate of roll. The wheel is pulled back or pushed forward to deflect the elevators, which control the angle of attack of the airplane's wing, and thus, taking engine thrust into account, the vehicles's speed, if allowed to stabilize.

The wheels and columns carrying them are interconnected, so moving one control moves the other. Unless some mechanical mishap has locked one in place, in which case an intentionally breakable link can be broken, by force, allowing them to move independently.

Note that the same physical object produces two different kinds of effect, one a rate, with zero near the middle, one, a position, which physics causes to control a rate, with zero beyond one extreme, (speed) not intuitively linked to it. Speed is also, very strongly, influenced by the engines' throttle position.

In a modern Airbus transport, a one-hand handle off on the outside of each seat pivots at it's base, seeming to "point" the airplane this way or that, but physics still separates the effect of roll, a rate, from the effect of pitch, a position, which, at equilibrium control speed, a rete, but not the intuitively obvious one. However, the captain's handle doesn't move the copilot's handle, so there's no visual or tactile link between the position of one control and the other. If each is moved in the opposite sense of the other, the result is zero roll rate and zero pitch angle.

In a General Dynamics (now Lockheed) F-16, there is a one-hand handle to the right of the pilot's seat, which does not move (in any significant way) but senses the direction the pilot is pushing it and moves the same control surfaces to accomplish the same pitch and roll control.

When 'blind' flying instruments for night and bad weather were invented, the authorities in Great Britian specified that all airplanes bought by the British government would have their blind flying instruments in a standard 2 rows by 3 columns layout. And thus, the Tiger Moth, de Havilland's popular cloth covered biplane, had an instrument panel that contained those six instruments in that arrangement. When deHavilland designed the Mosquito, the world's fastest production fighter-bomber at that time, they designed the instrument panel by mounting the Tiger Moth panel in the middle and adding additional switches, dials, etc, on additional panels on all 4 sides of the "basic 6". The Tiger Moth panel is curved at the top to match the top of the Tiger Moth's fuselage. Every Mosquito built has a panel with that same curve, and the add-on above it is curved to match...

Cultural norms play a large role too. The USAF studied moving tape/fixed pointer indicators in the 1960s, concluded that pilots could operate more accurately with them than "steam gauge" round instruments. But they cost more because of smaller volumes, more moving parts, they don't fit in a simple, round hole in the panel, and they're "different". Modern glass cockpits mix simulated moving tapes with fixed needles and simulated dials with moving needles. The instruments for some of SpaceShip One's cockpit were horizontal graphics on a laptop computer, which may have been time histories with vertical amplitudes...

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A side note regarding round instruments -- the P-51 Mustang had a large bank of secondary gauges off to the side, with "normal" readings at 3 o'clock needle position. The pilot only had to take a brief glance to the side to note if anything wasn't at 3 o'clock and needed further attention. If you were mixing it up with a Me-262, you wouldn't want to have to spend a lot of time reading each gauge. –  Phil Perry Mar 31 at 16:00
    
Good point. Racing cars used to have their tachometers mounted so that max RPM was straight up. In my opinion, round face indicators all pointing the same way are easier to scan than numbers or moving numbers against fixed pointers. USAF were looking at precision, not scan rate and anomaly detection... –  Bill IV Apr 9 at 2:37

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