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C-5 and C-17: An Assessment Of Airlift Options

By Loren B. Thompson, Ph.D.

This week's conference of House and Senate appropriators to iron out differences on the fiscal 2010 defense budget provides a setting for the latest cliffhanger in a long-running story -- whether the scrappy C-17 airlifter will survive, or finally cease production.

If appropriators side with the Senate and add ten more planes to the eight already funded in the fiscal 2009 supplemental war appropriation, then the line will continue running into 2011. If they side with the House and add only three, then prime contractor Boeing will soon have to send suppliers yet another warning about the impending shut-down of the line.

The C-17 has powerful friends in places like California (where it is assembled) and Connecticut (where the engines are built), but with everybody in the Obama Administration from the president to the defense secretary to the Air Force chief of staff gunning for it, its survival is by no means assured.

Oddly enough, one of the key characters in this suspense story seldom makes an appearance, either in the media or in floor debate. The giant C-5 Galaxy is the only other jet transport in the joint airlift fleet, and each one can carry about 50 more tons per flight than a C-17. What that means in practical terms is that it can transport twice as many armored vehicles or missile batteries or supply pallets per sortie. And while the C-17 is more agile, the C-5 lands every day in remote places like Kandahar, Bagram and Kabul -- a fact that seems to have been largely overlooked by those who want to replace Nixon-era C-5As with C-17s.

Another fact that has gone largely ignored is that C-5s on average still have two-thirds of their structural lives remaining, which would enable them to stay in service through 2040. A 2004 fleet viability board report found that the oldest C-5s have "no major structural life issues."

Unfortunately, that cannot be said of the plane's electronics and engines, which have given it a much lower mission-capable rate -- and much higher maintenance costs -- than the C-17. But the Air Force is funding a two-step plan to modernize the electronics on all 111 C-5s and replace the engines on newer C-5B variants. The resulting gains in readiness and reliability are so sizable that the upgrades will actually pay for themselves in lower operating and support costs. The plane will also be able to climb 58% faster and use shorter runways, allowing it to land in many more places. Prime contractor Lockheed claims that simply by modernizing the existing fleet of C-5s, the government can increase its airlift capacity by the equivalent of 24 C-17s.

C-17 builder Boeing vigorously disputes this, citing a 2008 Government Accountability Office report that found the military "would need to fully modernize seven C-5s to attain the equivalent capability achieved from acquiring one additional C-17." But the Institute for Defense Analyses (IDA) came to a seemingly contradictory conclusion this year, stating that, "retiring C-5As to release funds to buy and operate more C-17s is not cost effective." IDA found the option of modernizing older C-5As with new engines more appealing, noting that the government would incur no net costs from re-engining the whole Galaxy fleet because so many other costs could be avoided as the planes grew more reliable and productive.

Despite all the confusion, there actually is a bottom line here. It makes little sense to throw away airlifters with decades of service life remaining when they can be brought up to a reasonable mission-capable rate (about 75%) for no more money than what would have been spent to sustain them in their current state anyway. Whatever their drawbacks may be in terms of flexibility or versatility, they are able to carry much more per flight than a C-17 and the C-17's productivity advantage due to higher mission-capable rates diminishes considerably once the C-5s get better engines.

So the case for more C-17s needs to be grounded in evidence that 300 strategic airlifters are not enough to meet future requirements, rather than the unpersuasive argument that the Air Force should retire useful planes prematurely to make way for something better.

C-5 Versus C-17: An Assessment Of Airlift Options