Additional investments in C-17 aircraft may become more attractive. Currently, a new C-17 would cost about $276 million compared to $132 million to fully modernize a C-5. Each new C-17 potentially adds 100 percent of its cargo capacity toward meeting the total airlift requirement. Because the C-5s are already part of the operational force, each aircraft's current capacity is already counted toward the total requirement. Consequently, according to DOD data, the C-5 modernization programs only provide a marginal increase of 14 percent in capability over nonmodernized aircraft. Using DOD's million ton-mile per day planning factors, we, working in collaboration with DOD, calculated that DOD would need to fully modernize 7 C-5s to attain the equivalent capability achieved from acquiring 1 additional C-17 and the costs would be over 3 times more.
So, all things being equal, DOD can spend either $276 million on one more C-17 or $924 million on one more C-5M. I'm not an accountant, but I'm thinking the C-17 wins the ROI argument -- assuming DOD needs to buy more strategic airlift capacity in the first place.