The Shelf Lives of Warplanes

Saturday, August 1, 2009

The world’s largest single collection of military aircraft stands idle on the sands of Arizona’s Davis-Monthan Air Force Base. Many end up here, in the dry desert air, after decades of service in the U.S. Armed Forces. Others are ignominiously dumped at the base only a few years after acquisition. What determines their fate? Why do some military aircraft have long and useful lives, while others are short and unproductive?

Any nation’s air force has a number of unique missions: destroy enemy targets, protect bases, transport cargo, perform surveillance, rescue shot-down or crashed air crews, establish air superiority and more. For each mission, a certain type and number of aircraft are needed, each with a distinct set of  weaponry and equipment requirements, ranging from bombs to missiles, from maintenance facilities to support aircraft that provide aerial refueling, and more. All these elements and dozens more go into the assembly of a balanced, comprehensive fleet.

Military aircraft are useful only as long as they can accomplish their designated missions with reasonably good results. They must, of course, be able to survive – and, if possible, defeat enemy defenses while doing so. They must be affordable to purchase in sufficient numbers and to maintain once in service. They have to be as versatile as possible, to perform a variety of useful missions, rather than be restricted to addressing only a small portion of the demand on air support and services. Cost vs. Mission. Any service seeks to equip itself with aircraft that are able to perform all the tasks required of it, in any theater of operations, in a versatile, cost-effective and mission-effective manner. However, three elements are to be borne in mind.

• The most mission-effective aircraft for a given task may not be the most cost-effective or versatile. For example, to put a large weight of ordnance on target (as in the strikes against Iraq’s Republican Guard during Operation Desert Storm), the B-52 Stratofortress bomber is probably unequaled. However, it requires large, fixed air bases (typically at some distance from the combat zone), is limited in effectiveness against modern air-defense systems, and is expensive to operate in terms of crew, fuel and other costs. Furthermore, since it’s long out of production, losses are irreplaceable.

• The most cost-effective aircraft may not be the most versatile or mission-effective. A good example of this may be found in Iraq, where its renascent Air Force is seeking to acquire 36 propeller-driven Hawker Beechcraft AT-6B planes for counterinsurgency strikes. They’ll probably be very effective in the Iraqi Air Force’s current operating environment, where sophisticated enemy air defenses are almost non-existent. Put those same aircraft up against a modern air defense system, with radars, missiles and, coming soon, light-speed high-energy beam weapons, and they won’t stand much chance of survival. That’s why no military uses such aircraft for combat in, for example, Europe. They’d be low cost compared to jet strike aircraft, but their operational effectiveness in time of war would be minimal.

• The most versatile aircraft may not be the most mission-effective or cost-effective. A multi-role aircraft such as the Boeing F/A-18E/F Super Hornet of the U.S. Navy can handle many different missions: ground strike, air defense and interdiction, electronic warfare platform, tanker (with fuel tanks and refueling gear mounted beneath its fuselage and wings), and more. However, for close air support, troops in contact with the enemy typically regard such aircraft as too fast to clearly observe who’s friend or foe on the ground, with a correspondingly high risk of friendly-fire casualties. They prefer an aircraft like the A-10 Thunderbolt II, developed specifically and solely for close air support. It’s much slower and less sophisticated than the F/A-18, but much better at that particular task.


There has to be a balance between mission-effectiveness, cost-effectiveness and versatility. Inevitably, there are trade-offs.


The shelf life of a warplane can be defined as the period during which it can execute the tasks assigned to it in a cost-effective and mission-effective manner. If one parameter is deficient, then it becomes more of a liability than an asset. The older an aircraft becomes, the greater its maintenance costs, and hence the lower its cost-effectiveness. In the same way, mission-effectiveness is hampered if aircraft are too old and outdated to function in the current operating environment.

Success Stories. With the advent of reliable jet engines and supersonic flight in the 1950s, military aircraft entered an era of evolutionary rather than revolutionary development that lasted until the 1980s. Engines grew more powerful, new materials were invented and used, and electronics became more sophisticated. Many aircraft of the 1950s, however, would remain more or less comparable to those 30 years younger. Let’s examine three highly successful aircraft from that period, each from different branches of the service.

• The Navy ordered the McDonnell Douglas F-4 Phantom II as a fleet defense fighter. It entered service in 1960. However, it was so versatile and capable that the Marines embraced it with enthusiasm, followed by the Air Force and even many foreign air forces. Among its many roles, the Phantom flew as an interceptor, air-defense fighter, fighter-bomber, precision strike aircraft and electronic warfare platform.

Indeed, so successful has the F-4 proven to be that, today, it remains in front-line service in no fewer than seven nations: Egypt, Germany, Greece, Iran, Japan, South Korea and Turkey. The United States retired its last F-4s in 1996, but today uses them as radio-controlled target drones, and to launch ordnance for testing. It’s even been suggested that they could still be used in combat as very capable yet low-cost unmanned aerial vehicles, to strike heavily defended targets that might be too dangerous for a piloted aircraft to approach.

• The U.S. Air Force ordered the Lockheed C-130 Hercules as its medium tactical transport aircraft, following its experiences during the Korean War. It entered service in 1956. Since then, more than 2,000 have been produced, giving it the longest continuous production run of any military aircraft in history. It’s served more than 60 nations, on every continent, in roles including conventional air freighter, tactical air transporter, paratroop/airborne assault aircraft, gunship, search and rescue, scientific research support, weather reconnaissance, aerial refueling and aerial fire fighting. It’s been used for military, civilian and humanitarian missions.


The current-production C-130J Super Hercules is a fully modernized and updated version of the original aircraft. It’s been ordered by operators in eight countries, with several more expressing interest, and seems set to continue in production for at least the next decade. That will mean that the Hercules has been built for more than 60 years.


• The U.S. Marine Corps identified a need for a close-support aircraft that could operate from the Navy’s amphibious assault ships or from unprepared air bases on shore. This led them to consider the British Hawker Siddeley Harrier vertical takeoff and landing aircraft, which they purchased in its initial model. It entered USMC service in 1971.

Not satisfied with the performance of the original Harrier, the Marines wanted to develop it further. Britain was initially not interested due to the costs involved, so the Marine Corps approached McDonnell Douglas in the United States. Together, they developed the original aircraft into the AV-8B Harrier II, a far more powerful and advanced model. Britain ended up licensing U.S. technology to build its own advanced Harrier GR7/GR9 models.

The AV-8B entered service in 1985, replacing both the earlier AV-8 and the Douglas A-4 Skyhawk in Marine squadrons. It supported the Marine Corps during Operation Desert Storm and in subsequent action in the Middle East. Its vertical takeoff and landing capability has been the inspiration for one model of the Joint Strike Fighter project, and Harriers have served as test-beds to develop new technology. Almost alone among world military organizations, the Marine Corps remains committed to the use of vertical and/or short takeoff and landing aircraft, to give its air arm maximum flexibility in operating from any type of base, fixed or floating, under any operational conditions. The Strike-Fighter Solution. These three aircraft – the F-4 Phantom II, the C-130 Hercules and the AV-8 Harrier series – have all exhibited exceptionally long shelf lives, having been manufactured and in service for many decades. Other aircraft have proven less durable. For example, the F-105 Thunderchief, a U.S. Air Force contemporary of the Navy’s F-4 Phantom II, was produced for only eight years, from 1956 to 1964, with a total of 833 manufactured compared to more than 5,000 F-4s. Newer designs of the 1970s, such as the Air Force’s McDonnell Douglas F-15 Eagle and Lockheed F-16 Fighting Falcon, the U.S. Navy’s Grumman F-14 Tomcat and McDonnell Douglas F/A-18 Hornet, and the Army’s Sikorsky UH-60 Black Hawk, were more capable than earlier aircraft, but still used similar technology, albeit somewhat more developed.

One way of looking at an aircraft’s long-term cost-effectiveness is to compare its purchase price with the number of years it remained (or is projected to remain) in service.

Modern aircraft may not prove as long-lived as their predecessors. The 1980s ushered in a period of radical technological advancement that continues today. Stealth technology, Active Electronically-Scanned Array radar, more powerful computers, terminal guidance for many weapons, new-generation engines offering super-cruise, thrust-vectoring and other innovations, and new materials such as carbon fiber have combined to produce aircraft more capable than their predecessors. They also cost a great deal more. For example, the unit cost of the F-15A air superiority fighter, which entered service with the Air Force in 1975, was $27.9 million in fiscal 1998 constant dollars. A late-model F-15K for the South Korean Air Force in 2006 was said to cost $100 million. The F-15’s replacement, the F-22 Raptor, had a unit cost of $142 million in 2005.

Faced with this order-of-magnitude improvement in technology, and the immense increases in cost, all armed forces had to find ways to save money on their major equipment purchases. DoD decided to rationalize the future strike aircraft needs of the Air Force, Navy and Marine Corps, and develop a common solution. This became known as the Joint Strike Fighter program, which was won by Lockheed Martin’s F-35 Lightning II.

Unfortunately, the program has encountered significant delays and cost overruns, seriously affecting the Air Force, which made the decision in the 1990s to stop purchasing earlier-generation strike aircraft and wait for the F-35. This has resulted in many of its existing warplanes growing old and outdated. Some are approaching the end of their airframe lives. Their replacement is extremely expensive (the low-rate initial production unit price of the F-35 was predicted, in 2006, to be about $112 million), delayed in development, and not yet proven to deliver. What’s the Backup Plan? The Air Force initially planned to replace all its F-16s and A-10s with 1,763 F-35s. However, it’s admitted that budget forecasts won’t permit the purchase of so many, and that it won’t be able to afford to buy enough of them in time to replace existing aircraft as they reach the ends of their service lives. This will mean a drastically reduced fleet size and operational capability in manned strike aircraft. The Marine Corps is facing the same problem. The Navy, however, decided to continue purchasing F/A-18E/F Super Hornets, so it’s less affected by the delay in the F-35 program.

The U.S. Armed Forces have bet the farm on stealth technology, believing it will minimize threats from ground- and air-based radars, weapons and systems for the expected service life of the F-35. However, stealth may not be the panacea it’s made out to be. Developments such as pulsed-energy Nagira radar (Russia, 1995), Associative Aperture Synthesis Radar (Sweden, 2000), Celldar (Great Britain, 2002), digital beam-forming technology for phased-array radars (United States, 2007) and wake vortex detection using lidar (laser radar) have all been claimed to make stealth aircraft more detectable, although still less so than conventional aircraft. Further advances in detection technology are inevitable.

Another problem for the F-35 is that its weapons must be carried internally if it is to remain stealthy. This limits the quantity, weight and size of weapons it can deploy. It can carry more externally, but at the cost of a greatly increased radar cross-section, making it much easier to detect. To use internal weapons, it must open its weapon bay, also generating far stronger radar returns. In a high-threat environment, this may give defenses sufficient information to target it, particularly given the imminent advent of directed-energy light-speed beam weapons.

What will be the shelf life of the F-35? Improvements in air defenses may nullify its stealth advantages. The rapid development of unmanned aerial vehicles may allow them to perform many of the F-35’s missions at greatly reduced cost. Such factors may make the F-35 a vulnerable white elephant – or they may not.

That’s the trouble with an all-eggs-in-one-basket approach to aircraft purchases. If the F-35 is successful, despite its immense cost and prolonged gestation, the Air Force, Marine Corps and Navy will be well equipped for the next 20 to 30 years. If it’s not, the first two services will be in very serious trouble indeed, having no alternative available. Only the Navy appears to have a backup plan, with its ongoing purchases of the Super Hornet and its investment in unmanned combat air systems. These may be combat-ready by late next decade, perhaps replacing the F-35. Problems with Procurement. Meanwhile, the Government Accountability Office (GAO) has made it clear that perhaps the greatest obstacle in the way of a new, effective and long-lived series of military aircraft is DoD’s procurement process. “Systemic problems both at the strategic and at the program level underlie cost growth and schedule delays,” the GAO reported in June 2008. “At the strategic level, DoD’s processes for identifying war-fighter needs, allocating resources, and developing and procuring weapon systems – which together define DoD’s overall weapon system investment strategy – are fragmented and broken. At the program level, weapon system programs are initiated without sufficient knowledge about system requirements, technology and design maturity. Lacking such knowledge, managers rely on assumptions that are consistently too optimistic, exposing programs to unnecessary risks, cost growth and schedule delays.”

The procurement process needs to be de-politicized. Members of Congress, whose priorities might be more closely aligned with defense contractors who employ their constituents, should be less involved in the process. The GAO’s recommendations on program selection, balancing requirements against available resources, and a sound business approach to program management should be vigorously pursued. Finally, the armed forces must break their habit of overpromising system capabilities while underestimating the money and time it takes to get a new, high-tech warplane off the ground. When research and development last longer than the operational life of an aircraft, the cost of such relatively brief shelf lives can run into the billions. The question our nation faces – as technology evolves and the cost-effectiveness gap widens – is whether a new and improved procurement process will produce better results. It certainly cannot hurt to try.   Peter Grant lives in Louisiana and writes extensively on aviation history and aircraft technology.