Brett wrote:

snip

It can
launch from a major airfield, and land on unimproved runways in the battle
zone.

The C-5 can still perform that mission I believe, it doesn't mean that any
mission planner would suggest it be used in many situations for either the
C-17 or C-5.

While the C-5 was theoretically able to land on unimproved strips, in practice
it is never done. The same hasn't been the case with the C-17, which was so
used in Afghanistan (FOB Bravo), at a minimum. The USAF wasn't all that
enthusiastic about the idea, but the Marines needed its larger payload, so it
appears CINCCENT (if not even higher up the chain) told the USAF to stop
dragging their feet and use the a/c as it was designed to be used. USAF also
refused to land their C-130s at max. gross landing weight on unimproved strips
in either Afghanistan or Iraq (I forget which) for much the same reason (using
up remaining fatigue life), which didn't make the U.S. Army (IIRR) very happy.
Since the USMC own their own KC-130s they can keep the argument in their own
chain of command, and find it easier to order instead of having to negotiate.

Guy