March 21, 2010: For the second time in a year, a U.S. Air Force C-130E was retired after 47 years of service. This one (tail number 9813) had spent 33,220 hours in the air, and flew its last mission in Iraq, serving in a combat zone to the end.

Last year, another 47 year old C-130E transport, after 30,100 flight hours, was sent into retirement. That aircraft was one of dozens of similar aircraft being pulled out of service, even though they have a few thousand hours left in them. These C-130s have undergone six or more refurbishments since they entered service in the 1960s. But these aircraft require more maintenance because of their age, which makes them more expensive to operate, and less available for service than newer models.

On average, C-130s last about 25 years, and about 20,000 hours in the air. But averages are just that, and some aircraft get lucky. If an aircraft has relatively few, "high stress" (heavy load, rough weather) flights, it will fly longer. The key component in C-130 longevity is the center wing box. This component takes the most punishment, and if it suffers corrosion, as well as enough stress to cause metal fatigue, it usually means the useful life of the aircraft is much shorter.

The C-130 has been in service 51 years. So far, nearly 2,300 have been built, and it is still in production. Most C-130 built are still in use, although that will change in the next decade as the large number built in the 1960s and early 70s retire.

Several other military aircraft remained in service over half a century (the British Canberra, U.S. B-52 and DC-3, the Russian Tu-95 and AN-2). But no other aircraft has remained in production for so long. In many respects, the C-130 is the heir to the 1930s era transport, the DC-3, which saw heavy use in World War II. Over a hundred heavily patched and rebuilt DC-3s continue to serve as working transports in obscure parts of the world, more than 60 years after they rolled off the production line.

Originally, the C-130 was designed to carry 15 tons of cargo, 92 troops, or 64 paratroopers. The latest version, the C-130J, has a top speed of 644 kilometers, a range of over 12,000 kilometers, and can carry 20 tons of cargo. The C-130 is used by more than 50 countries.

When retired, U.S. military aircraft usually end up at a storage yard in the dry southwest, where the aircraft can be cannibalized for spare parts, until the remaining bits are sold for scrap. Those most recently put in storage are kept intact for as long as possible, so that they can be recalled to duty if there is a national emergency.