On Oct 7, 7:58 pm, Mxsmanic wrote:
Bertie the Bunyip writes:
You gotta have some good old fashioned stuff for backup..

Well, until recently you did anyway!

I fear what may happen when there is no longer a back-up--or when pilots
forget how to use the back-ups.

Also, while you may have some back-up instruments, a situation that would be
both safe and manageable with a complete avionics suite in working order can
become dangerous and unrecoverable if you have only a handful of instruments.
There are some things that you can do with fancy avionics that you cannot do
with just two or three steam gauges ... otherwise there'd be little point in
the fancy avionics. But this inevitably means that there will be situations
that are safe with the fancy stuff that become deadly without it, even with
back-up instruments.

Flying with three or four instruments is fine as long as you limit your flying
to situations that can be handled by those instruments. Of course, if you
have a fancy glass cockpit, you may well go far beyond those situations, and
if the glass cockpit then fails, you're in deep trouble.

MX,
I am gonna break a cardinal rule here and respond to one of your
posts.I am doing this because you have raised a question others might
be interested in. I cannot speak for other jets ( I am sure they are
similar) , but the Boeing uses an ADIRU which has 2 sets of three
laser ring gyros either set will sufice to measure acceleration, pitch
and roll. And there is an ADIRU for each side of the cockpit (Capt &
FO). The IRS will also provide attitude info and there are two of
those also. Keep in mind you can switch the display to all on system
one or two. With this level of redundancy we dont even practice
partial panel or raw data stuff in the sim, it is simply not
necessary. Years ago I flew an approach with just backup instruments
in a turbo prop after a total EFIS failure and it was no big deal. I
think you might be making more of this than you need to.
KB