Bob Noel wrote:
In article xdcrf.15668$LB5.8651@fed1read04, wrote:


I have serious doubt that the U.S. airlines will ever retrofit their
legacy glass aircraft. Boeing wants a king's ransom to do that. The
757/767 fleet manager at American said, "No way, it would cost as over
$100 million."


what am I missing here... American's 757/767 fleet has what kind of
glass? Is the architecture so tightly integrated that processors and software
can't be upgraded (even as part of tech refresh)? Is there additional
equipment that needs to be added? How many aircraft?

Any of their 757s/767s delivered after some date (circa 1995?) have the
required stuff. That is when Boeing switched to GPS as the primary
sensor and the Pegasus FMS. These birds can do true RNP and
radius-to-a-fix legs (RF legs).

American's fleet is capable of RNP-2, isn't it? If not, then they should
be looking at some upgrade cost anyway.

RNP 2 is not much of anything, and can be done with DME/DME in the en
route environment. Containment areas for RNP 2.0 is 4 miles, centerline
to edge, no different than a VOR airway. For RNAV departures the term
of reference in FAA-dom is Level 1 (RNP 1.0) and Level 2 (RNP 2.0)
Level 2 accomplishes little, if anything.

To get into the performance-based approach game, RNP 0.3 is required
just to enter the game. RNP 0.1 is where it all is going, and that
simply will not happen with the 757/767 pre-Pegasus avionics. The
hardware is too old and rigid. They would have to rip out the old FMSes
and replace them.

To get down to RNP 0.1 you need some pretty nifty software routines that
will compute and estimate ANP (acutal navigation performance), you need
redundancy to achieve an E10-7 target level of safety, you need the
latest EGPWS (TAWS) with peaks and obstacles, and you almost certainly
need at least one IRU. With three IRUs that are updated by dual,
independent GPS sensors, and two (better three) independent FMSes, you
have the absolutely best performing platform.

When you are threading between the rocks at RNP 0.10 and possibly lose
GPS, you don't want to be DEAD reckoning. ;-)

(btw - $100 million? feh - you don't want to know the cost to upgrade
the USAF fleet...)

The Air Force has the necessary eqippage in some of the new stuff. I
doubt they will be doing much retrofitting of avionics except for
special-use aircraft.