On Oct 7, 4:55 am, Bertie the Bunyip wrote:
Phil wrote in news:1191732077.235895.295410
@w3g2000hsg.googlegroups.com:



Ideally, every instrument should be designed to convey the appropriate
information in a way that is conducive to how that information is
going to be used. If you just need a value, then a digital display of
a number make sense. If you need to have a sense of where you are
relative to minimum and maximum, then a display showing relative
position in a range should be used. The nice thing about a
computerized display is it can be set up to display the information
either way.

Well, not in the things I fly! They pretty much give you what has been
decided for you.


Sorry, I wasn't very clear there. What I meant was the designer of
the computer display can program the pixels to convey the information
either way. The display can show simply a number, or it can show a
graphical representation of a range of values with a pointer to show
the current position in the range. Right now you are stuck with
whatever the designer chose for you, but as EFIS becomes more common
and more sophisticated, it is very possible that it will be re-
configurable by the pilot. I doubt that it will ever be completely
flexible where you can get it to display any way you want, but I can
imagine that there might be a selection of four or five different ways
to display an instrument, and you can pick which one you like.

One thing I positivley loath on some modern EFIS displays is the "track
up" option on the nav screen. For those not fmailiar, basicallly the DG
function puts our actual ground track on the lubber line and has a bug to
indicate your heading. This is the reverse of the traditional display where
the heading is on the lubber line and if you have some sort of RNAV
comouter giving info your track is displayed by a bug. It's OK when you are
motoring along enroute, but if you arent used to it, shooting an approach
is a nightmare. Adherents of track up say that it is actually easier, but
it isn't if you are used to the old way. doing an NDB appraoch, for
instance, all you need to do is put the track on the lubber line and the
ADF needle should stay glued to the inbound track, but if you have to
constantly remind yourself to do the oppostie of what you are used to it
can be an absolute nightmare to do by hand. If we did NDB appraoches every
day of the week it wouldn't be a problem, but I've done one in anger in the
last five years and the rest are all in the sim.

That makes me wonder how the designers of EFIS displays choose their
designs. Are the designs based on research or are they just the
personal preferences of the designer? Hopefully there is some kind of
objective research used to choose a display pattern that is easiest to
use. Of course, that raises the whole issue of testing displays. Who
do you get to test them? If you use pilots who have been flying
analog gauges for years, you are probably going to find that they want
EFIS displays that are like the analog instruments. But those
displays may not actually be the optimal way for the brain to digest
the information. It makes me think about the keyboard I am using to
type this. It was designed back in the days of manual typewriters.
Because manual typewriters tended to jam if you tried to type too
fast, the keyboard was arranged to slow the typist down. So we are
all using a keyboard that forces us to type more slowly than we could
with an optimal keyboard. The Dvorak keyboard was designed to
eliminate this problem. But hardly anyone uses it because we have all
been taught to type on the old QWERTY keyboard.

Even weirder, the newer airbusses use a speed reference system that uses
groundspeed on the approach. so, you set your Vref and the airplane
automatically raises it to accomodate a headwind by flying a constant
ground speed. (or advising you to fly faster by pushing the speed bug up)
It's simple, but interferes with the pilot's direct communications with the
wing. I suppose I'm trying to say it's translating for you and somethng is
always lost in the translation..


I understand what you are saying. In the software world, designers
try to make each new release more "helpful" than the last. Sometimes
this is good, but mostly I just find it annoying. The software tries
to guess what you intend to do, and do it for you. If it guesses
right, that's fine. But it seems like it mostly guesses wrong, and
then you just have to un-do what it did. That's not an improvement.
I wish they would put more time into designing simple, intuitive user
interfaces so I can more easily tell the program what I want it to
do. That way the program doesn't have to guess.

But don't mind me, I wish the 75 had flying wires so I could hear them sing
to me..

Maybe some EFIS designer can set up the option to have the airspeed
converted to a flying wire sound and played in your headset. :-)

Phil