2 Background

The A-10 is the only single-purpose attack jet in the U.S. Air Force, as reflected in its “A” designation indicating “attack” (U.S. Air Force, 2005). Its 30 mm cannon protrudes downward from its blunt nose like a tusk, prompting its affectionate nickname of “Warthog.” The A-10 entered service in 1975 and saw extensive action in the 1990–1991 Gulf War, the no-fly zones enforced against Saddam Hussein’s regime following that conflict, NATO’s no-fly zone over Bosnia and Herzegovina and its 1999 air campaign in Yugoslavia, the Afghan War, the second Iraq War, and operations against ISIS (U.S. Air Force, 2015a). In all these conflicts, the A-10’s primary role has been CAS.Footnote ¹

When the air campaign to defend Kosovo required close-in targeting, NATO commanders preferred A-10s to AH-64 Apache helicopters due to the latter’s vulnerability to antiaircraft fire (Lambeth, Reference Lambeth2001, p. 28–29, 51, 55). In fact, two A-10s survived direct hits from antiaircraft artillery (Lambeth, Reference Lambeth2001, p. 108–109). During Operation Anaconda, in the Tora Bora region of Afghanistan in early 2002, AH-64 Apache helicopters again proved excessively vulnerable to fire from the ground. A-10s were deployed to fill this capability gap due to their unique survivability while providing highly precise CAS (Cordesman, Reference Cordesman2003, p. 68). A-10s were a cornerstone of CAS capability during the 2003 invasion of Iraq, performing the vast majority of precision strafing runs and again replacing attack helicopters after disastrous losses from ground fire (Lambeth, Reference Lambeth2013, p. 263–264, 383). In late 2014, a small number of A-10s were transferred from Afghanistan to support Iraqi forces battling ISIS (Clark, Reference Clark2014). In the conflict with ISIS, the A-10 has remained unchallenged in its ability to strike a large number of targets and make multiple attack runs with great precision (Pellerin, Reference Pellerin2016).

Despite this distinguished record on the battlefield, the U.S. Air Force has had an uncomfortable institutional relationship with the Warthog.Footnote ² Critics assert that Air Force leaders have sought to terminate the A-10 since its inception because of an entrenched preference for high-technology fighters and indifference toward the CAS mission (Pierre Sprey, quoted in Wheeler, Reference Wheeler2013). A 2003 op-ed in the New York Times alleged that the Air Force was planning to retire the entire fleet of A-10s, replacing them with F-16s and later with F-35s (Coram, Reference Coram2003). The Air Force denied then that any such plan existed (Hornburg, Reference Hornburg2003). The issue resurfaced in 2013, when the Air Force first went public with its proposal to terminate the A-10 (Mehta, Reference Mehta2013).

On March 4, 2014, the Pentagon formally announced plans to retire the entire A-10 fleet.Footnote ³ The Air Force Chief of Staff testified “painful budget cuts” in FY15 required retiring the A-10 (Marshall, Reference Marshall2014). The Pentagon projected savings of $3.7 billion in future program costs, in addition to $500 million to be saved on discontinued upgrades to the A-10s. The Air Force assessed three alternatives to achieve a similar budget reduction given the pressure of sequestration: reducing the number of F-15s, trimming the F-16 fleet, and delaying the procurement of F-35 Joint Strike Fighters (Marshall, Reference Marshall2014). These three options were rejected in favor of a fourth option, which the Air Force proposed and the U.S. Department of Defense (DOD) accepted: terminate the A-10 fleet outright. The F-35 was proposed to take on the A-10’s traditional roles and functions, notably CAS (Marshall, Reference Marshall2014). Congress blocked the A-10’s retirement in FY15, but the Air Force and DOD reintroduced this plan in the FY16 budget (Everstine, Reference Everstine2015, see also U.S. Department of Defense, 2015a). The GAO cast doubt on the A-10 retirement plan in a 2016 report to Congress, concluding that the Air Force had neither performed a credible analysis of CAS requirements nor provided a sound basis on which to compare alternatives to meet its budget targets (Government Accountability Office, 2016, p. 2).

The A-10’s increasing significance in Syria and Iraq prompted a modest change in the FY17 budget submission: a recommendation to phase out the Warthog fleet over 5 years (U.S. Department of Defense, 2016). Secretary of Defense Ash Carter, testifying before Congress, cited the A-10’s payload capacity for conducting large-scale strikes on ISIS as a reason for delaying the full retirement of the fleet until 2022 (Lendon, Reference Lendon2016). Nevertheless, this budget entailed the phased replacement of A-10s with F-35s, beginning in FY18 (Seligman, Reference Seligman2016a).

The FY18 budget proposal backtracked further. The Secretary of the Air Force offered this assurance: “When we look out 5 years, they’re still in the Air Force inventory” (Machi, Reference Machi2017). The FY19 budget similarly imposed no immediate threat of retirement. However, the A-10’s place in the arsenal is hardly secure. There are good reasons to expect the replacement plan to resurface in future budget proposals. First, the Air Force has long considered this plan to be a pillar of modernizing its aircraft fleet; such institutional commitments are hard to reverse. Second, the Air Force has not abandoned its core argument in favor of replacement: that it would be a cost-efficient way to maximize airpower and is superior to acknowledged alternatives. Finally, the FY18 proposal was $54 billion higher than the FY17 defense budget, a 10% increase that substantially reduced the need to economize (U.S. Department of Defense, 2017a). The FY19 budget was higher still at $717B in total, thus reducing pressures to make hard tradeoffs on capabilities (U.S. Department of Defense, 2018e). The FY20 budget may be as high as $750B (Hicks et al., Reference Hicks2019). But, reason dictates that defense budgets cannot increase indefinitely. When austerity does strike, the plan to have F-35s supplant A-10s will likely resurface.

4 Low-intensity conflicts: Their likelihood and CAS requirements

The 2018 National Defense Strategy (NDS) focuses on major power adversaries while acknowledging the continuing terrorist threat from groups such as ISIS (U.S. Department of Defense, 2018f). This strategy is intended to drive defense spending for the foreseeable future, and is the intellectual foundation of budget proposals through FY20 and counting (Hicks et al., Reference Hicks2019). The NDS asserts “long-term strategic competitions with China and Russia are the principal priorities for the Department” (U.S. Department of Defense, 2018f). To counter modern-state adversaries like China and Russia, U.S. forces must deter them and, if deterrence fails, defeat them in high-intensity warfare. The possibility that competition and conflict in a range of realms could escalate into a major war clearly justifies investing in advanced weapons systems, of which the F-35 is a prime example. Similarly, to defeat ISIS and other terrorist groups, including new ones to emerge in the future, the U.S. military must be well equipped to fight low-intensity conflicts. The security of the USA and its allies requires effective preparation for both high- and low-intensity conflicts.

Fortunately, the likelihood of a high-intensity conventional war is low. The global economy intertwines the interests of states in ways that generally make high-intensity wars unappealing lose-lose scenarios, particularly given the potential for nuclear escalation leading to millions of fatalities. Therefore, the USA and its allies will presumably make every effort to avoid a war with a near-peer adversary such as China or Russia. Decision makers in those countries will likely be equally reluctant to provoke such a conflict, as they have been for decades. The primary purpose of advanced weapons systems such as the F-35 is to deter adversaries from initiating high-intensity wars or taking actions that could precipitate such wars.Footnote ⁶

If a high-intensity war were to occur, advanced stealth aircraft would be indispensible. The F-35 is a prime example of a weapon this worst-case scenario would call for. In a conflict with a modern state, the F-35’s advanced technology and signature characteristics of SSR would be critical for penetrating integrated air defenses, shooting down hostile aircraft, and clearing the way for ground forces and other airplanes like the A-10. The F-22 and F-35 are explicitly missioned to protect and support other aircraft in “advanced threat environments” where enemy air-to-air and ground-to-air threats are numerous and highly capable (U.S. Air Force, 2014, 2015b).

Although non-stealthy aircraft like the A-10 might not be able to operate independently in advanced threat environments, they could nonetheless perform critical functions in a high-intensity war. A full-scale war with North Korea is one example that the NDS considers as a serious possibility (U.S. Department of Defense, 2018f). Presumably, after an initial high-intensity battle for air superiority, attack aircraft would be required to find and destroy numerous ground forces, particularly tanks, dispersed and camouflaged in mountainous terrain (Project on Government Oversight, 2014). The A-10 was purpose-built to destroy armored vehicles and tanks, as well as human targets, and is exquisitely suited to this mission (U.S. Air Force, 2015a).

A combination of other aircraft including unmanned aerial vehicles (UAVs), gunships, and bombers, cannot provide an equivalent capability. These aircraft have characteristics and capabilities significantly different from those of A-10s and multirole fighters. Attack helicopters have excellent sense of the ground environment, which we may call “ground sense,” but are lightly armed and vulnerable to direct fire (Project on Government Oversight, 2014). Gunships are heavily armed propeller-driven aircraft that lack speed and maneuverability. UAVs can orbit or “loiter” for long periods over a specific area, but lack the ground sense of manned aircraft and have limited strike capabilities. None of these platforms could replace the specialized CAS capability of the A-10, nor could a combination of them (Government Accountability Office, 2016, p. 1). The closest comparison and best replacement for the A-10, if it is to be replaced, is the one that the Air Force has proposed: a multirole fighter (U.S. Air Force, 2014). As the GAO noted, the loss of CAS capability involved in retiring the A-10 cannot be hand-waved away on a belief that a variety of other platforms will somehow make up the difference (Government Accountability Office, 2016, p. 16). Consequently, this analysis focuses on a one-to-one comparison of the A-10 and its proposed replacement, the F-35.

Low-intensity conflicts (U.S. Department of Defense, 2018d) include counterterrorist operations, irregular warfare, and hybrid wars that blend conventional and unconventional elements (Hoffman, Reference Hoffman2007). Unfortunately, the USA appears likely to continue to engage in low-intensity conflicts. Virtually no policymakers paid attention to ISIS half a dozen years ago. Yet, in August 2014, a new low-intensity conflict emerged in Iraq and Syria with the rise of ISIS. In Iraq, the USA provided special operations advisors and air support to the Iraqi Army and Kurdish Peshmerga forces (Landler & Gordon, Reference Landler and Gordon2014). In 2016, Iraq undertook a major operation to clear Mosul, its second largest city. Dug-in ISIS units refused to surrender in the face of overwhelming firepower and held out until the summer of 2017. Fighting to the death, ISIS troops had to be literally blasted out of their positions with airstrikes (Cooper, Reference Cooper2017).

In Syria, a U.S.-led coalition supported the Free Syrian Army, Kurdish militias, and other groups resisting ISIS (Lemmon, Reference Lemmon2017). This proved to be a true hybrid war, given that ISIS conducted terrorist operations, such as car bombings, in addition to fielding regular forces including tanks and artillery. By late 2017, Kurdish-led forces had encircled ISIS’ self-proclaimed capital of Raqqa and began clearing it block-by-block under the cover of coalition airpower (Lemmon, Reference Lemmon2017). An entire squadron of A-10s was assigned to provide the extremely precise CAS required within the dense urban core of Raqqa, for example to strike point targets at the feet of five-story buildings (Rhynes, Reference Rhynes2018). ISIS retreated after months of hard fighting, and by late 2018 had lost almost all territory.

The USA and its allies may need to engage in this type of warfare outside the Middle East. There are many other potential low-intensity threats. Gangs plague Central America and contribute to instability near the southern border of the USA (Jones, Reference Jones2012). Al Qaida is weakened but remains a terrorist network with a global reach, and ISIS has spread well beyond the Levant (Kirkpatrick, Reference Kirkpatrick2015). Boko Haram, a jihadist group in northwest Africa, pledged allegiance to ISIS in 2015 (Callimachi, Reference Callimachi2015). In 2017, ISIS militants ambushed a joint U.S.-Nigerien patrol in the remote Tongo Tongo region of Niger; they killed four U.S. special operations troops and five Nigerien soldiers (Searcey & Schmitt, Reference Searcey and Schmitt2017).

Russia’s annexation of Crimea and its military support to separatists in Eastern Ukraine (Parfitt, Reference Parfitt2015) represent major breaches of international norms within Europe (Mankoff, Reference Mankoff2014). In response, NATO member nations have provided equipment and training to Ukrainian forces fighting the Russian-backed separatists (Gordon & Schmitt, Reference Gordon and Schmitt2015). Ukraine could become a flash point that precipitates a high-intensity conflict, or the current proxy war could simmer indefinitely. Moreover, the case of Ukraine demonstrates that low-intensity conflicts are dangers that can emerge anywhere, not just in the Middle East and Africa.

Conflicts with terrorists, insurgents, and other irregular adversaries remain highly likely; they reflect the military reality facing the USA and its allies for many years to come (Kilcullen, Reference Kilcullen2009, p. 2–27). The Trump administration recognizes terrorism as a prevailing threat to U.S. national interests (McMaster & Cohn, Reference McMaster and Cohn2017). The NDS, in contrast, prioritizes building up advanced conventional forces to widen the competitive advantage over China and Russia (U.S. Department of Defense, 2018f). It follows that the defense budget invests in weapons of high-intensity war at record levels (U.S. Department of Defense, 2018c). This strategy risks over-investing in forces and capabilities suited to potential mission requirements, at the expense of concrete ones. The plan to retire the A-10 fleet to buy a few more F-35s exemplifies this misalignment in the NDS: it does not rationally balance the valid need for high-end deterrence against the reality of the low-intensity wars the USA will surely keep fighting.

Low-intensity conflicts invariably require extremely precise airstrikes, but seldom entail much air-to-air combat. Terrorist and insurgent groups usually do not have aircraft (Lambeth, Reference Lambeth2005, p. 84–87). Advanced weaponry and overwhelming military power seldom deter irregular adversaries. Deterrence fails because these groups rarely have a physical center of gravity that can be captured or destroyed.Footnote ⁷ They are usually ideologically motivated and resigned to deaths among their members. Moreover, they can easily disperse into local populations. Al Qaida continues to actively threaten the USA, although much of its leadership has been eliminated. Although ISIS highly valued and fought desperately to retain its core territory in the Levant, it is unbowed by severe losses (Cooper, Reference Cooper2017). The logic of deterrence simply does not apply to groups that are prepared to fight to the death. The successful prosecution of low-intensity conflicts involves actual operations, not deterrence.

In the current political and strategic environment, U.S. policymakers plan to leverage increasingly the precision, stealth, flexibility, and relatively low cost of special operations forces to perform these operations (McRaven, Reference McRaven2013). The United States Special Operations Command (SOCOM) expanded at an unprecedented pace between 2001 and 2017, from 45,690 to 70,000 troops and from a $2.3 billion to an $8 billion budget (Lohaus, Reference Lohaus2014, p. 31; see also SOCOM, 2000, p. 93; Thomas, Reference Thomas2017; SOCOM, 2016, p. 3). This vast increase in resources for SOCOM reflects its role as the primary U.S. force for low-intensity conflicts, particularly those against insurgent and terrorist groups (Thomas & Dougherty, Reference Thomas and Dougherty2013, p. 4–5, 45, 46, 77).

Special operations forces sometimes act alone. More often, they work alongside complementary ground forces, such as soldiers and Marines, in joint operations. In conflicts requiring a mass effort across a large and populous nation, conventional units will predominate with special operations in supporting roles: the counterinsurgency in Iraq following the 2003 invasion is a prime example (Lohaus, Reference Lohaus2014, p. 38–43). In low-intensity conflicts that require a less obtrusive U.S. presence, special operations units perform most, if not all, combat operations.

Foreign partner forces supported by U.S. troops and air power also rely heavily on CAS.Footnote ⁸ Although U.S. forces have not engaged in direct ground combat in Iraq and Syria, they have provided extensive assistance from just behind the front lines. This includes directing CAS for Iraqi troops, Syrian Kurdish militias, and other partners engaging ISIS in close combat (Nordland & Cooper, Reference Nordland and Cooper2015, Yan et al., Reference Yan, Levs and Labott2014). In both countries, U.S. and coalition aircraft have struck hundreds of targets in close proximity to friendly forces, civilians, or both (Nordland, Reference Nordland2015, see also Yan et al., Reference Yan, Levs and Labott2014). In 2015, these strikes successfully removed 1,000 ISIS irregulars from the battlefield each month (John W. Hesterman III, quoted in Marshall, Reference Marshall2015). The coalition sustained this blistering pace of CAS success through the ensuing 2 years (Cooper, Reference Cooper2017). There is anecdotal evidence that A-10s have been outperforming multirole fighters in this conflict, where the CAS requirement includes both high volume and high precision. By 2016, a small number of A-10s were accounting for nearly one-third of U.S. strikes in Iraq and Syria (Pellerin, Reference Pellerin2016), and had dropped 13,856 total weapons (Woody, Reference Woody2018).Footnote ⁹ These strikes are reported to have been highly accurate against, for example, point targets in the heavily populated city center of Raqqa (Rhynes, Reference Rhynes2018). In future low-intensity conflicts, highly accurate CAS in support of foreign partner forces will remain a critical requirement, whether those forces operate on their own or with U.S. special operations troops directing airstrikes for them.

Low-intensity conflicts present unique and intense CAS requirements. Ground troops fighting terrorists and insurgents need aircraft to strike individual human targets that are fleet, mobile, disguised, and dangerously close to civilians and/or friendly forces. Insurgent needles must be picked out of civilian haystacks; in short, precision CAS is required.

Skilled irregular adversaries like the Taliban employ elaborate systems of lookouts to spot aircraft with the naked eye or to identify the sound of their engines. When approaching aircraft are detected, the Taliban know to go to ground. Given favorable conditions, they will open fire from bunkered positions against low-flying aircraft. Helicopters, especially vulnerable to this form of attack, are a favorite target.

Insurgents are hard to pinpoint from the air. They skillfully blend into civilian populations; they appear and disappear suddenly on the battlefield. They often stage attacks from civilian homes, hoping that excessive firepower and imprecise airstrikes from counterinsurgents will unintentionally harm civilians, undermining the counterinsurgents’ legitimacy. A March 17, 2017, airstrike in Mosul resulted in 105 civilian deaths. An investigation found that ISIS had baited the coalition into bombing a building where displaced civilians had been deliberately gathered as targets.Footnote ¹⁰ This tactic permits one poorly placed bomb to unravel months of careful counterinsurgency work, thereby promoting strategic defeat.Footnote ¹¹ Disciplined irregular troops will also “hug the belt,” attacking from extremely close range so that airstrikes endanger counterinsurgent forces (Hackworth & Sherman, Reference Hackworth and Sherman1989, p. 488). Such risks from friendly fire became evident when an errant airstrike from a B-1B bomber accidentally killed five U.S. servicemen in Afghanistan in 2014 (Londoño & Salahuddin, Reference Londoño and Salahuddin2014).

Precision CAS under these conditions requires a highly effective ground-air team, a super-system composed of two separate and distinct systems: a ground force and an aircraft with its pilot. Ground troops in heavy combat are usually sweaty, dusty, exhausted, and extremely stressed. Hearing the unflappable calm of pilots on the radio, sometimes referred to as the “voice of God” (Wheeler, Reference Wheeler2013), reassures them. Pilots see the big picture of the battlefield and can relay what they observe over a wall or beyond a rise in the terrain. On the ground, troops have a close-up view and a nuanced feel for what is happening, identifying detail not visible or not interpretable from the air. The experience and information acquisition of these two “systems” effectively complement one another.

Specially trained JTACs link the two components of the ground-air super-system. In some units, they are full-time specialists, such as Air Force combat controllers. In other units, such as SEAL Teams, they have been cross-trained to control aircraft in addition to other duties. JTACs provide air expertise to commanders, control the airspace over ground forces, and call in strikes. Given their training, experience, and responsibilities, they are acknowledged experts on the use and effectiveness of CAS. Therefore, we surveyed JTACs for their views on the requirements for precision CAS and on the performance of various U.S. aircraft.

5 JTAC Survey

6 Data set: Afghanistan Airstrikes 2011

7 Performance analysis: The A-10 versus the F-35

A quantitative analysis comparing the A-10 and the F-35 measured the difference in performance. Results from survey questions 12–15 and Air Force fact sheets were used to determine the performance of the two aircraft on the eight attributes identified above. The A-10 has the advantage on the six most important attributes. The F-35 has the advantage in speed and stealth. The A-10 also has the advantage in range, based on U.S. Air Force fact sheets (U.S. Air Force, 2014, 2015b; fact sheet data are summarized in Table 5).

We assigned a utility score of 3 to the aircraft with the advantage. On each objective, the lesser aircraft received a utility score of 2 if the difference in capability was small and of 1 if the difference was large.Footnote ²⁴ The A-10 received a 0 for stealth because it has no radar stealth capability.

These raw effectiveness scores for each attribute were weighted with respect to importance for low-intensity conflict (weight), using the mean value provided by the JTACs in question 1 of the survey.Footnote ²⁵ This approach followed the direct assessment method described by Melese et al., treating the JTACs as the “decision makers” for purposes of weighting (Melese et al., Reference Melese, Richter and Solomon2015). A distinction is that our weights are on a 1–7 scale (see Table 1). The weighted scores were then summed to yield a total low-intensity conflict score for each of the two aircraft (A-10 utility score and F-35 utility score).Footnote ²⁶

Table 1 Dimensions of CAS capability and importance (question 1).

Table 2 F-35 and A-10 head-to-head comparison (question 6).

The A-10 dramatically outscored the F-35, 104.36–62.24. This was inevitable, given its superiority on the six most important characteristics, and its notable superiority (scoring 3 versus 1) on the two most important. This analysis indicates that cancelling the A-10 would significantly and unacceptably hurt the U.S. CAS capability.

To check whether our results were robust to plausible alternate performance scores, the authors provided a questionnaire to additional highly experienced JTACs asking them to provide their own scores. Three JTACs completed the questionnaire; their scores are shown in Table 7.Footnote ²⁷ JTAC no. 1 was much more favorable to the F-35, giving it the advantage on six of eight attributes. However, he scored the A-10 higher, 3-0, on ground sense and gun effectiveness, so that the A-10 beat the F-35, 85.17–80.04. JTAC no. 2’s scores were somewhat more favorable to the F-35 than the authors’, resulting in the A-10 winning 105.82–84.68. JTAC no. 3’s scores were similar to the authors’, resulting in the A-10 winning, 106.53–62. These results show that our analysis and its results are robust to alternate performance scoring of the two aircraft. The CAS performance of the A-10 under low-intensity conflict conditions is clearly superior to the F-35.

Table 3 Importance of fixed-wing aircraft for ground strikes in addition to multirole fighters (question 8).

This interpretation is robust to changes in the weights of each attribute. Using the original performance scores in Table 6, if we increase the weight given to stealth and speed, the two attributes where the F-35 has the advantage, to the maximum value of 7, the A-10 still retains its overall superiority. Indeed no plausible weighting, given a low-intensity conflict scenario, shows the overall CAS performance of the F-35 to be superior.Footnote ²⁸

Table 4 A-10 and multirole fighter capabilities comparison (questions 12, 14, and 15).

Table 5 U.S. Air Force fact sheet data.

Table 6 Overall effectiveness of A-10 and F-35 in low-intensity conflict (LIC).

Table 7 Alternate performance scores.

Table 8 Cost comparison of A-10, F-22, and F-35.

Table 9 Alternative air fleets and F-35/A-10 ratios.

Proponents of the replacement plan argue that the F-35’s versatility, termed “multimission capability,” outweighs other factors (Schogol, Reference Schogol2012). However, versatility is but one consideration. Multimission aircraft are not better by definition. They are only better if they can perform the required set of tasks more effectively and efficiently than some set of single-purpose alternatives. Here that is not the case. Despite its impressive SSR, the multimission F-35 is markedly inferior in terms of CAS performance to the aircraft it would replace. The A-10 performs a single critical task, precision CAS, far better than the proposed alternative and at far lesser cost.

8 Cost comparison: The A-10 versus the F-35

Costs are a central consideration, the primary one stressed by the Air Force to justify cancelling the A-10 fleet. Given that replacing paid-for A-10s with to-be-purchased F-35s would be extremely expensive, as this section shows, claims of cost savings are not credible.

The Air Force has presented its plan as a cost-saving response to tight budget constraints (Marshall, Reference Marshall2014). The F-35’s touted cost savings would theoretically emerge because large purchases would produce substantial economies of scale (U.S. Department of Defense, 2018a). Winslow Wheeler, a defense budget researcher and former Government Accountability Office analyst, determined that the cost of one F-35 would range between $148 million and $337 million depending on the variant, with an average cost of $178 million.Footnote ²⁹ Lockheed Martin, which manufactures the F-35, has claimed this cost will drop to $65 million in future years (Stephen O’Bryan, quoted in Pike, Reference Pike2014). Lockheed also forecasts that operating and support costs would fall sharply, to half those of current aircraft (Wheeler, Reference Wheeler2011). Wheeler (Reference Wheeler2011) has argued persuasively that similar past claims have proved unfounded. The cost-per-flight-hour (CPFH) to operate the F-35 is $67,550, even more expensive than the F-22 at $58,059 CPFH, and more than three times the per-flight-hour cost of the A-10 at $19,736 CPFH (Bender & Nudelman, Reference Bender and Nudelman2016; see also Project on Government Oversight, 2014).

In the most optimistic scenario, sufficient quantities of F-35s would be produced to allow learning to bring down procurement costs (but not operating costs) from their current extremely high levels to those comparable to current-generation fighters. The claim, however, that the F-35 will ever be significantly more affordable than currently owned aircraft lacks both logic and precedent. High-technology aircraft almost always become more expensive with each new model. The F-22 cost more than four times as much per airplane, $143 million, as the F-15 it was intended to replace (U.S. Air Force, 2005). The Air Force claimed that the F-22 “will have better reliability and maintainability than any fighter aircraft in history,” making it highly cost-efficient over time (U.S. Air Force, 2005). Yet the F-22 remains vastly more expensive to operate than aircraft such as the A-10, F-15, and F-16 (Project on Government Oversight, 2014).

Technological problems have persistently plagued the F-35, and continue to increase its cost. The Defense Department’s Office of the Director of Operational Test and Evaluation (DOT&E) 2017 report noted many weapons defects: its gun is inaccurate; it cannot engage moving targets; and it cannot correctly predict the “time on target” when a bomb will strike, a basic requirement for operating with ground forces (U.S. Department of Defense, 2018b, p. 43–45). Its automated maintenance system is vulnerable to cyber-attack and is underperforming, contributing to disappointing reliability well below program targets (U.S. Department of Defense, 2018b, p. 53, 55). Its advanced helmet-mounted display system has failed frequently and is being re-engineered (Smithberger, Reference Smithberger2015). Aerodynamic flaws limit its ability to make aggressive maneuvers (Grazier & Smithberger, Reference Grazier and Smithberger2016). An upgrade plan to remedy these deficiencies is estimated to add $16 billion to the F-35 program’s total cost (Insinna, Reference Insinna2018a).

Obviously, procuring F-35s at any price would be more costly than the continued operation of the 172 A-10s, refurbished with new wing sets, which are already on hand. Despite the A-10’s age, its CPFH is less than one-third of the F-35’s (Project on Government Oversight, 2014). The A-10 is a relatively simple, subsonic, non-stealthy aircraft. It is comparatively cheap to build and to fly. Replacements will be required in 2035 when these upgraded A-10s will have reached the end of their extended service lives. Until that time, however, replacement would be a profligate measure.

Let’s put actual costs aside. The efficiency of the A-10 and F-35 could be compared using a hypothetical procurement scenario. Consider a case in which the USA had to buy all new aircraft, and could only buy new A-10s or F-35s, and procurement and operating costs for the two were equal. Even given all new procurement, our effectiveness analysis shows that the varied capabilities of a mixed fleet of A-10s and F-35s would yield more military utility than would a fleet composed exclusively of F-35s. In a theoretical scenario where the USA could purchase only two aircraft, it would be most efficient to purchase one of each. The F-35 would be allocated to deterrence and air dominance roles for high-intensity conflicts; the A-10 would be allocated to precision CAS for low-intensity conflicts. Positing a more realistically sized fleet of many hundreds of aircraft, the USA, seeking efficiency, would purchase a mix of A-10s and F-35s. How many of each would depend on the estimated likelihoods of the two conflict scenarios, and on the performance of the fleet as the numbers of each type of aircraft increased. Given the A-10’s substantial superiority in low-intensity conflict, as well as the far greater likelihood of this type of conflict, no objective analyst could recommend purchasing an all-F-35 fleet. Only if a low-intensity conflict were extremely unlikely could an all-F-35 fleet make sense.

The real procurement decisions facing the USA are much more agreeable than this hypothetical scenario. The USA already has all the A-10s it needs. Two hundred eighty-one of them are currently in service; 172 of those have been refurbished for a service life extension through 2035. The remaining 109 A-10s could be refurbished for much less than the cost of purchasing new A-10s, and for far less than the cost of purchasing new F-35s.Footnote ³⁰

Training CAS-specialist pilots is another important cost factor. A-10 pilots have been trained at great cost to perform their roles and functions within the aircraft-pilot system. Many have acquired substantial combat experience in Afghanistan, Iraq, and Syria (Adelan, Reference Adelan2017). Retraining them to fly F-35s would entail considerable start-up costs.

The A-10 provides substantially more capability for the critical mission of CAS than does the F-35, at a fraction of the cost, however it is tallied. This conclusion recognizes the possibility of a high-intensity conflict and concedes the F-35’s vast superiority in that scenario. Given both conflict scenarios and the differences in capabilities of the two aircraft, our analysis demonstrates that a mixed fleet is the preferable option for the USA.