(Al Dykes) wrote in message ...
Why did we decide to design and build the C-17 instead of continuing
to make and upgrade the C-5 ?

One big reason is versatility; the C-17 can deliver cargo into and out
of airfields that the C-5 can't access very well, if at all. This
negates a big chunk of the cargo transfer requirement, where C-5 cargo
is cross-loaded into tactical airlifters like the C-130. Add in the
ability of the C-17 to move "C-5 sized" loads into those more
remote/small/rough airfields, something that even the C-5/C-130 combo
can't make happen.

Brooks