As U.S. Air Force planners struggle to balance their final budget request for this disappointing decade, it is becoming increasingly apparent that many of the service's planes will require the aerospace equivalent of geriatric care for the foreseeable future.

Despite all its talk about revitalizing America's military, the Bush administration has failed to arrest the decline of U.S. air power, passing on to its successors a decrepit fleet that is grounded or flight-restricted much of the time.

Keeping this fleet airworthy requires continuous, massive infusions of money and manpower. The service expects to spend a billion dollars per week in fiscal 2010 on fuel, spare parts, repairs and technical support -- and that doesn't even include the paychecks for military personnel performing such functions.

Much of this cost is the inevitable consequence of operating a diverse fleet of 6,000 high-tech planes around the world on a daily basis, including those committed to ongoing military campaigns in Iraq and Afghanistan.

But there is little doubt the budgetary burden of sustainment would be more bearable if the Clinton and Bush administrations had done a better job of replacing aging aircraft. Instead, the U.S. Air Force will enter the second decade of the new millennium with 500 Eisenhower-era Boeing KC-135 tankers averaging 50 years of age, 300 Lockheed Martin C-130 transports exceeding 40 years of age, and Vietnam-vintage Boeing McDonnell-Douglas F-15 Eagle fighters that are literally falling out of the sky.

According to one estimate, a third of the entire fleet is either unavailable or operating on restricted basis on any given day due to maintenance problems such as metal fatigue, corrosion and missing parts. Such problems multiply with age as the stresses of operational use accumulate and suppliers cease making parts for planes that have gone out of production.

As the cost of maintenance mounts, it begins to drain money from modernization accounts that might have been used to buy new planes, accelerating the decline of the fleet. In addition, when a large portion of the fleet is too old to operate efficiently, planners tend to rely heavily on newer planes to accomplish missions, which makes them age faster. For example, the C-17 transport and KC-10 tanker are both being overworked in Iraq.

The U.S. Air Force has tried hard to improve its logistics practices, but it is impeded in achieving the best results by members of the U.S. Congress intent on protecting local jobs.

Legislators often block the retirement of worn-out planes and interfere with the allocation of maintenance workloads, for example by insisting that a set percentage of heavy repair work be performed by federal workers at government sites. It isn't hard to see why the legislators are so intent on protecting the jobs of government maintainers: U.S. Air Force logistics sites are typically the biggest industrial employers in their states.

While the U.S. Air Force can't escape the need to keep Congress happy, it can be more flexible in the way it goes about allocating work for the support of its aging fleet. For instance, it has begun to get away from the practice of automatically assigning discretionary work to the companies that originally manufactured aircraft, and it should continue seeking the best value in future awards such as the pending competition to provide support for KC-10 tankers.

The service needs to continue tapping the marketplace for sources of talent and innovation in providing sustainment. Now that U.S. Air Force leaders know they won't be getting a budgetary windfall to cover unfunded needs, they must do whatever they can within the service to free up money for new planes.

(Loren B. Thompson is chief executive officer of the Lexington Institute, an Arlington, Va.-based think tank that supports democracy and the free market.)