REFLECTOR: EFIS

[Douglas O Hayes <dohayes@juno.com>]

>My approach is to provide a primary "glass" system that gives me all of
the information I need for >normal operations and provide the
old-fashioned cluster (electric miniatures) for the emergency >and cross
checking in an out-of-the-way location on the panel.  Rather than going
with >something like the Sierra dual redundant configuration which is
prone to two failures of the >same kind.

Are you sure either the Sierra or Archangel systems are actually running
two separate programs in the two screen mode? The impression I got is
that there is that there is a single processor doing everything, and that
having two screens simply allows you to display EFIS and NAV
simultaneously and protect against a screen failure. If you get the
optional battery backup to protect against electrical failure, you are
still faced with the possibility of a software crash.

>The Archangel folks puff themselves up like its something special to
have an FAA TSO for their >box.  It seems they should be LOWERING the
price by $15K on a TSO'd box instead of raising it.

Having FAA certification is great for marketing though, you must admit.
Its says: "we're serious", "we're in this for the long haul", and  "our
system must be good, since the FAA likes it". Not to mention the fact
that now all those people with a lot of money can double the cost (forget
value)
of their old certified airplanes. One would like to think they could
lower their prices as sales go up, but only competition will do that, and
as Archangel is likely to be the only TSO game in town for the
foreseeable future, it just won't happen.

Back to the redundancy issue: there are a lot (if not most) of personal
aircraft flying around out there without two gauges monitoring every
engine function and flight condition, so why should I have that type of
redundancy just because I'm using new-fangled, electronic
instrumentation? If Sierra and Archangel will take the time to reveal
enough details to help me decide if their systems are trustworthy, and I
design a panel with the type of indirect redundancy that you have with a
vacuum attitude indicator and an electric turn coordinator for example, I
shouldn't have to. While I'm at it, I'll try not to notice that all of
their sample panels have one-for-one redundancy for every important
instrument...

So here is what I'm thinking: The Archangel system is capable of doing
everything, which is nice, but unless I'm willing to buy two complete
systems that can run with two separate processors and electrical systems,
I'm probably going to have to fill the other side of my panel with
old-timey backups. Except for the gee-wiz factor, what's the point? If I
pull out the $30,000 glass goodies I'm left with what every other
airplane already has.  Archangel has announced that they are making part
of their system available separately - for homebuilders no less. It was
all so cryptic that I have no idea what they are talking about , but this
might help once we figure it out. The Sierra system on the other hand,
comes as an option without attitude indications, which allows us to save
over $10,000 and have a separate vacuum attitude indicator that is
actually performing a function besides waiting for a failure of the
primary system. Sierra also has the mysterious remote indicator so that,
along with your attitude indicator, you can maintain control of the
aircraft while you look at the NAV display. This option includes a
built-in GPS by the way, further reducing over-all costs. A CDI like the
Terra Tri-Nav can display VOR/ILS or GPS course guidance, and also has a
timer. And finally, there are several all-in-one gauges that monitor
various inputs and sound an alarm when something bad happens, without
constantly displaying the information and cluttering up the panel. I
think all of this can be done for less than the price of the full Sierra
and Archangel systems, and it gives you several places to look for
information should anything fail, as well as both electrical and vacuum
power.

Doug Hayes
Velocity 173FG
Boulder, CO

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