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Regardless of which aircraft type and manufacturer, the character keys on any Flight Management Computer are always in alphabetical order, see image: FMC (picture from LH Systems)

From a human factors view, this is sub-optimal, so why? Where does this order come from?

From chats with pilots I learned that you get used to it easily and can type quite fast with this alphabetical layout, but still, we are all used to the QWERTY or QWERTZ layout...

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    $\begingroup$ Not always every single aircraft, though most do. The A380 has QWERTY keyboards on its FMC and another pair of QWERTY keyboards on the fold out tables. $\endgroup$ – Zach Lipton Jan 19 '18 at 7:39
  • $\begingroup$ I don't have a source for this (or I'd post an answer), but I'd imagine size is a primary constraint for why it largely hasn't changed. Once someone started building the things the size they are, it's clear 10 reasonably-sized keys across won't fit. Short of a major cockpit redesign, as clearly happened with the A380 (and the 787, which is still alphabetical), the form factor constrains the choice of keyboard layout. $\endgroup$ – Zach Lipton Jan 19 '18 at 9:47
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"we are all used to the QWERTY or QWERTZ layout..." or AZERTY. But which one? Universally there is no one standard, so whichever of these 3 (and others) is chosen, it will be wrong for some users. So the only standard left is simple alphabetic.

Another thing to consider is that the QWERTY-types of layout were chosen to deliberately slow down typists on mechanical typewriters. This slow-down is not necessary on an electronic piece of kit, so the pure-alph format is quite fast once you're used to it.

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    $\begingroup$ "Slow down" is not exactly the thing I believe. The reason was to avoid consecutive neighbouring letters to avoid hammer collisions. $\endgroup$ – yo' Jan 19 '18 at 13:31
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    $\begingroup$ Why slow down the typists? $\endgroup$ – ymb1 Jan 19 '18 at 14:10
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    $\begingroup$ @ymb1: To prevent hammer collisions, until IBM re-invented THE typewriter. $\endgroup$ – mins Jan 19 '18 at 14:48
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    $\begingroup$ QWERTY layout indeed spreads letters so that most likely the next letter will be typed with the different finger (English text assuming). This is still very good for fast typing as you can start reaching for the next key before the current keystroke is finished. Who wants to type with one finger only really needs completely different layout with frequent combinations on adjacent letters rather than spread but on a long run will not be faster. $\endgroup$ – h22 Jan 21 '18 at 19:51
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The placement and form factor of these keyboards is not suitable for applying a classic touch-typing technique.

To touch type as professionally trained, a keyboard must be in front of the typist, equally accessible with both hands, with limited number of rows (palms must stay close to the "standard position"). The keys should not make vertical rows, keys in adjacent horizontal rows must be slightly shifted, the key size is dictated by finger size and cannot be too small. The standard key placement is helpful, but also other can be learned as long other requirements are met (which, for these keyboards, are not).

Just putting letters in QWERTY order is not helpful. Probably nobody writes novels, computer software or E-mails to multiple customers on this keyboard, so limited typing speed is not much a problem.

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  • $\begingroup$ You raise a good point, but I would like to see some sources for it. I can't see why no matter the keyboard placement or actual key placement, the design wouldn't still include QWERTY, to which most people from the early 1900s typewrite-era to modern day computer keyboard are would've been used. I definitely spend more time searching for keys in an ABCD-keyboard than QWERTY... Also why would you have two layouts anyway? Furthermore the A350/A380 both feature two keyboards per pilot that both now have QWERTY-layouts. The keyboard in place of the FMGS (A32S) is thus now also a QWERTY. $\endgroup$ – rkantos Jul 27 at 11:12
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we are all used to the QWERTY or QWERTZ layout...

Now we all have computers and most of them come with QWERTY keyboard. However in 70's when the early FMS were designed, computers were mainly in research institutions and big companies and most pilots would never use one (though their dispatch might have had some by that point). So most people would only see the layout on a typewriter and average pilot didn't need that either. So most pilots probably were not used to the layout back when it was created.

And since then, since some pilots were already used to the previous design, it was always more useful to stick with that design.

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