"André Somers" wrote in message
...
John Gilbert wrote:

Angular guages perhaps. Sweeps of 180 to 270 degrees are quite
readable, I agree. But what does the study say about altimeters with
dual needles, that rotate multiple times? How many times have you
misread the altitude or had to think hard to get it right? This has to
be the most confusing instrument to read, unless you don't really care
about knowing about that last +/- 1000 feet.
Well... hardly ever, but maybe that's because our meters are, well, in
meters :-) That means a full spin round is 1000m. Not something you'd
easily misjudge I think.

André


I've flown airplanes with metric instruments (And Russian placards too).
The airspeed, rate-of-climb, RPM, manifold pressure were no problem.
Numbers is numbers I guess - fly with the needles in the green arc and
everything works. But that damn metric altimeter was impossible - no way to
read trends on an instrument that insensitive. With an altimeter that reads
1000 feet (304.8 meters) per rev of the big hand, you can thermal by
watching the trend of the needle.

Responding to "YO": Some people like analog gauges and some don't.
Ergonomic studies just produce averages which may be useful to marketeers
but what's important individually is what works best for that particular
user. If the data are displayed on an electronic screen, the user can
select the display method in a setup dialog box. i.e. check box one for
round gauge analog, box two for vertical tape with a digit window etc...
Check another box for metric or imperial units. With altitude in meters,
expanding the scale of a vertical tape gives the same sensitivity as with
imperial units.

I've also flown with both vertical tapes and round gauges. At first the
tapes were confusing but once adapted to the idea of having all the "V"
speeds floating alongside the tape with the trend indicators, going back to
round mechanical gauges seemed like the stone age. I vote for computer
graphic displays of primary flight data.

Graphical displays are inevitable anyway since all those little watchmakers
who built and repaired mechanical instruments are all retired or dead now.

Bill Daniels