The C-5 is one of the 'coolest' planes in the USAF, just because of its capacity and the awe factor (if you're in the US haven't yet, go to one of the open house type things your local AFB has usually once a year. I don't know how 9-11 will affect this, though). All of the things in The Custodian's writeup being true, the C-5 fleet has one very big disadvantage:

It breaks down more often than a Chevy.

Let me give you some background info on how I know this.

The USAF has a thing called 'space-available travel,' in which active duty personnel and their dependants (like me) can effectively hitch a ride to wherever the transport is going, if there is space available on the plane. Normally there are a few seats lining the sides of an airplane next to the cargo, and if you don't mind all the noise and playing the odds of whether or not the plane actually goes, it's a nice free trip about the country and the world.

The C-5 can carry roughly 80 people onto a trip, making it rather popular on this sort of outing. By comparison, the average medical flight will have 5 to 20 seats available, as will most any other plane you can space-a with.

The reason I know this is because I've flown on a half-dozen space-a flights and I have never seen a C-5 actually make its takeoff time. In fact, I've only heard of one or two taking off at all! An aircraft engine mechanic friend I know in the Air Force, stationed in Okinawa, took a guess for me that at any one time about half to three quarters of the C-5's in the USAF run well enough to take off and land anywhere nearby.

This relates, of course, to why the AF wanted to get some C-17 Globemaster III's into the fleet, though the writeup on that explains why I'm not so sure about them, either.

So that's the bad news. Thing is, even if only half the C-5's are running ... they could still take the home of you and most of your friends from one end of the Earth to the other :)