Is it a habit we prefer mechnical instruments?

Didn't we just go through this.

Digital instruments are easy to program and don't take much computing
resources. Converting the display to a form fit for human consumption
take more computing and programming horsepower.

But it is still very little compared to a PC. With today's "stuff" an
old 6502 would probably have enough power.

Exactly right. Plus two additional problems:
1) Most modern general purpose computers have voluminous operating

What do general purpose computers have to do with flight displays.

With reasonable luck, nothing.


systems and take too much time to cold start (or boot up), even if ROM is

Actually the operating systems can start in seconds. It's all the
other stuff they have to load and interface with that takes the time.

This may be a semantic argument, but we seem to agree that starting with a
general purpose computer and OS would be less than obtimal--to understate
the situation.


substituted for the disk drive. That means a lot more programming.

Programs for flight displays should be relatively simple. Compared to
a "windows" or "Mac" they should be extremely simple.

2) Presently, there is too little standardization, especially of the
NAV

With this I agree to a point, but to say too little? There isn't any!

No argument there.

equipment. And integration of the NAV display(s) is a major reason for
considering electronic displays.

So it's not that we necessarily prefer mechanical instruments, but we
certainly have reason to demand that any replacement be at least as good
in
all ways important to a pilot, such as:
1) Ease of comprehension.

Glass panel

Actually, I agree with you. My point related back to the OP, which seemed
to ask whether our preference for an analog airspeed indicator (as an
example) was merely habitual, or the result of a true preference based on
the nature of use. Obviously the latter, as others described at length
earlier in the thread.

In point of fact, at my rate of progress toward getting a project under way,
I will almost certainly have a glass panel system installed prior to initial
completion; and for all of the usually cited reasons: lighter weight, lower
cost, more advantageous display format, and equal or better redundancy and
reliability of the complete system.

2) Similarity of controls and displays in aircraft a pilot might fly.

Actually with most using Garmin there is a lot of similarity, but for
those moving between different systems it can be more than a little
confusing.

Exactly.
3) Redundancy--at least as good as our old electrical plus vacuum.
4) Immunity from "wash out" in direct sunlight.

A properly configured system should have none of these problems.
LCDs can be constructed to be easily viewable in direct sunlight.

True. It just needs to be included as a specification--no matter how
confident anyone is that "everyone knows."

I own both a mid-range digital camera and one of the supposedly better
camera equiped cellular phones. Both are from respected manufacturers and
the displays become useless in something less than real direct sunlight. I
own other devices that share the problem; however the two that I mentioned
were purchased with the idea that I could use them outdoors...


Glass panels are more reliable, and once the pilot becomes proficient
with one they are easier to interpret than the old mechanical gages. A
good MFD with The AI, Heading, airspeed and altitude is far easier to
scan than mechanical gages.


My only disagreement with you here is one of nomenclature. I believe that
the AI, heading and airspeed are part of what is now being called the
Primary Instrument Display or possibly the Primary Flight Display. Most NAV
data would be part of the MFD, and a lot of redundancy is gained when the
fuctions can be swapped or overlayed in the case of a display failure. I
believe that (display swapping) means of redundancy was first developed for
military use, but has since gained fairly wide acceptance.

In many cases, little if any transition time will be needed when the display
is essentially similar. And there is an added benefit that the display
capability previously available only for fighters and heavy transports can
be economical in light singles in terms of both weight and cost.

Taken in logical order and one step at a time instead of trying to do
everything on the first flight, they are easy to learn as well. The
confusion comes when a pilot jumps into a plane with an unfamiliar
system and then tries to use all the bells and whistles instead of
just flying around for a while getting aquatinted with the system.

Especially dtrue for the current range of NAV equipment; and probably the
radar and COM equipment as well.