[LAD] A GUI request

[Fons Adriaensen]

On Tue, Jun 07, 2022 at 08:49:36AM +0200, Thorsten Wilms wrote:

> So far I thought the differences are all about much higher requirements
> on readability at a glance and stableness.

Not just 'at a glance' but also in exceptional circumstances
and under stress. For example imagine your aircraft is damaged
and shaking violently. Your eyeballs will be shaking as well.
Now if you have a series of identical items arranged in a line
on a display, it will be extremely difficult to read them, you
just won't know which is which. Also imagine having to use a
touch panel in those conditions, it would be just impossible.

> More contrast

Enough but not too much. Lighting conditions can be extreme in
a cockpit. If you're landing e.g. at LGIR (Herakleon, Crete)
on RWY 27 in the late afternoon you will be looking straight
into the sun for minutes and wearing sunglasses. Come a few
hours later and it will be pitch black. Displays must be
readable and not induce eye fatigue in both cases. BTW, since
most flat panel displays produce polarised light, pilot's
sunglasses must NOT be polarised.

> avoiding superfluous styling, no deep layering.

Yep. And no animation, popups, etc.

> Being able to rely on training much more.

You rely and training and professional knowledge instead of
random 'exploration'. Which also means function is indicated
using standard (English) words or acronyms, and not by icons 
(which can be much more ambiguous than most people imagine).
Also accessibility is not an issue.

> Fons, do you have examples of such guidelines that don‘t work
> for cockpits, that may surprise the layman? 

Many (if not most) computer applications are about 'editing'
some sort of document. Even a DAW fits into that category
when used to create music - but not e.g. when used 'live',
just as a mixer and/or playback device.

Controlling an aircraft (or any machine) is something very
different. So the whole set of standard menus like 'File',
'Edit', 'Tools' etc. doesn't make much sense.

Some of the requirements could be unexpected. For example
it needs to be unconditionally clear if some function is
'active' or just 'armed' (meaning it will automatically 
become 'active' later). Or if some displayed value is the
'actual' one or the 'target' one that e.g. an autopilot
will try to achieve. Usually this is done by consistent
use of colour.

That said, all controls that directly affect operation will
be hardware ones, not items in a menu or toolbar. Displays
such as the PFD and NAV panels are just displays and not
used for input. The only exception to that would be the
MCDUs - the things in the central pedestal between the
pilots that look like a 'calculator on steroids'. These 
provide an interface to almost everything in a modern
aircraft. Recent models actually have a trackball and
are used much like a conventional PC application. But
they are for setup and information lookup only. 

There are two important aspects of user interface design
in a modern 'glass cockpit', and they can be at odds:

* Maintain situational awareness. Automation is fine but
the pilots need to aware of what it is doing at all times.
This can be quite complex.

* Avoiding information overload in emergency conditions.
Pilots are trained to prioritise and divide their tasks,
but this can still be a problem, and a lot of research
is done to avoid it.

Ciao,

-- 
FA