Re: Boeing 767-400

Date:         03 Jan 97 04:36:34 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
References:   1 2 3 4 5
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>Aren't there considerable weight savings in going to electronic controls
>especially in terms of wiring which can be reduced significantly with
>the use of a communication bus instead of wires to each components from
>the cockpit ?

That was an early claim for FBW, but in practice the difference seems
to have been negligible.

>How much of the 767-400 built today would really be "conventional" with
>a conventional cockpit of a 767 built in early 80s ?

You seem to be confusing two different things -- the controls the
pilots interact with in the cockpit, and how those controls connect
to the flight control surfaces.  A very modern looking glass cockpit
can still have mechanical connections to the control surfaces.  The
747-400 is an example.  An old "dials and guages" type cockpit can
use FBW to activate the control surfaces.  Except for the side-stick,
Concorde is a good example.

Ignoring the first few 767s which were built with a flight engineer's
panel (which was subsequently ripped out before certification -- see
the archives for details), the cockpit of a 1996 vintage 767 is pretty
much the same as the first one delivered to United in 1982.  There are
probably some new bells and whistles, but the core flight controls
aren't substantially different.

The connections to the control surfaces and whatnot are even less
changed, with the exception of the engines -- all new 767s have FADEC-
equipped engines, so engine controls are now electrical.

>What I am really asking: if Boeing chooses a conventional cockpit, will
>the training to cross-certify pilots really be less than if the
>767-400's cockpit adopts the 777-style cockpit ?

If the 767-400 ends up with the same cockpit as the earlier 767, the
additional training would not be substantially more than that required
for a pilot to fly both the 767-200 and -300, which isn't a whole lot.
Airlines that have both the 757 and 767, which were designed to have
very similar cockpits, generally certify pilots for both models.

If the 767-400 gets a 777-derived cockpit, it would almost certainly
require a completely different rating than other 767s, just as the
747-400 requires a different rating than "rope-start" 747 models.
It might well be easier to certify pilots for the 767-400 and 777 in
that case -- and not the 767-400 and older 767s.

>Would the savings in training be offset by higher operating costs due to
>the heavier plane ?

Weight would be a function of FBW vs. cables, pulleys, and hydraulics,
which as noted above is probably not significant.  Training costs in
this context are mainly a function of the cockpit design.  It's very
unlikely Boeing would try to convert the 767-400 to FBW, so even it
were to get an updated cockpit, it wouldn't gain any theoretical
weight advantage.

Karl Swartz	|Home
Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills