Cost of Cockpit Instruments

Recently, Le Chaud Lapin posted:

On Sep 23, 12:55 pm, "Neil Gould" wrote:
Recently, Le Chaud Lapin posted:

The dentist's XRay machine was either set up incorrectly (perhaps by
an uncertified person?), or operated improperly. As for Shuttles, by
and large they are experimental crafts with many possible points of
failure. The risks are known and willingly undertaken by the
participants, just as are the fliers of experimental aircraft and
drivers of experimental vehicals (racing comes to mind).

The point is that I that think that the "beware the danger of COTS"
attitude is too extreme for the actual risk involved. There is
always some risk.

The general public are not willing to take such risks, nor should
they be subjected to them unknowingly. The recent recall of toys and
baby furniture underscores this last point. If I'm not flying an
experimental plane, I don't want the same risk levels as those that
do. And, if I *am* flying an experimental plane, I'd want good
knowledge of what makes it experimental. In the case that you're
creating, it would be uncertifiable components in an otherwise
normal aircraft. Like Blanche, that would make me rather
uncomfortable in some flight conditions.

The public is willing to take such risks. Ever technology advance
that posed some risk to human users initially was tested by guinea
pigs. The world is filled with them. Thy average automobile has
quite a few alone. We still use them because, attitudes change over
time, along with improvements in the technology. Instead of constanly
asking, "What if this fails..what if that fails...", reason takes
over, and people start looking at the likelihood of failure, along
with consequences. Eventually, we take for granted certain things
simply won't happen, even though they do occasionally.

Unlike the typical automobile driver, we regularly train for those things
that are unlikely to happen simply because occassionally they do happen.
We are not generally willing to take unnecessary risks that increase the
likelihood of such occurances.

Is it true that if COTS components were used, airplanes with fall from
the sky by the 1000's? 100's? The truth is that we do not know,
becuase few people are doing it.

One point that is being overlooked is the low tolerance the public has for
failures in GA. We hear about almost every crash, and every one where
there is a fatality. Every crash brings on a rash of law suits blaming
just about every manufacturer of every component, regardless of how
unrelated to the incident that component may be. Sticking some COTS
component into that environment will only negatively impact GA for the
short duration that the company that provides the component survives the
legal onslaught.

Incremental improvement, using
extremely expensive devices, is the alternative, devices that still
fail occasionally.

When you get down to it, this isn't really about how possible it might be
to reduce the price of cockpit instruments, it's about the cost of levels
of comfort. The public has one, component manfacturers another, and pilots
yet another.


So I think the same thing could happen in aviation. There is a
trade- off between pain and pleasure of assumption. There is
probably a point where the cost would be so low from using
(well-engineered) COTS components that the risk of using them is
superseded by the value that they would bring.

How would one know if COTS units were "well-engineered", except by
trial and error? Take, for example, the recent problems with the
certified G1000 (see other topics about this). The failures were
attributed to some supplied components in an otherwise
"well-engineered" design. Now, IMO, if the design was all that
well-engineered, either those units would have failed on final
inspection (the preferable outcome) or the design would have
tolerated the components and operated properly without problems.
Take the certification process out of the equation, and who knows
what one would get?

Well, at least this goes to show that there is no guarantee. Even
certified componenets might fail.

This isn't about the possibility of failure as that is inescapable. It's
about cost of the effort that goes into preventing failure and/or
predicting MTBF. Even with certified instruments it isn't a guarantee, but
at least there is some effort to establish those factors.

Well, I have an idea of what one would get. As one who has bought and
built many computers over the years (I build them when my
requirements are more stringent than COTS can deliver), I can tell
you that all brands of either full systems or basic components are
not of equal quality. The same would be true for COTS cockpit
instruments.

That's always the case for different manufacturers. That would not
bother me at all. If the more expensive components made me feel
safer, I would buy it. If I knew that the cheaper component would
likely material no material effect, I would buy it.

How would you know?

Certification means that the instrument will perform at a particular level
of accuracy and reliability regardless of who manufactures it. Failures
will still happen, but nothing even remotely close to the level of
unreliability that COTS items deliver.

This is true for non-critical components in an aircraft, and might
be true for many critical components.

I seriously doubt it.

Most technologies gradually move toward commoditization and ability to
interconnect, mix and match, etc. The rate at which this happens
often has less to do with technical capability, but more toward
perspective and attitude of systems designers.

The bottom line is that you can build your experimental aircraft using any
kinds of mix and match COTS components that you want. However, should you
have an accident, it won't matter how reasonable you thought that approach
was, or even whether those components were at fault.

Neil