Aircraft of the 379th Air Expeditionary Wing and coalition counterparts stationed together in a deployed location in southwest Asia fly over the desert April 14, 2003. Aircraft include KC-135 Stratotanker, F-15E Strike Eagle, F-117 Nighthawk, F-16CJ Fighting Falcon, British GR-4 Tornado, and Australian F/A-18 Hornet. Master Sgt. Ron Przysucha
Photo Caption & Credits

A Better Way to Measure Combat Value

Nearly every form of U.S. joint power projection relies on effects delivered by modern air forces: air superiority; the kinetic or nonkinetic destruction of targets; air mobility; persistent intelligence, surveillance, and reconnaissance (ISR); and secure command and control (C2). Every joint force operation involves some element of the Department of the Air Force. This cannot be said of the other services. To ensure victory in future conflicts, the United States should prioritize investments in aerospace capabilities that provide the greatest mission value in the types of conflicts in which the nation is most likely to engage. 

While cost per flying hour is a common metric … such measures are far from infallible.

William LaPlante, former assistant secretary of the Air Force for acquisition

Harnessing an analytical cost-per-effect assessment system will be essential to making these best-value choices. 

Yet cost-per-effect assessment should not be limited to the Air Force. It should be adopted and applied across the Department of Defense (DOD) as the preferred means of evaluating weapon system choices. Cost-per-effect can be used to explore comparative “business cases,” driving competing systems to increase mission effectiveness and fiscal efficiency. Today’s penchant to compare upfront unit costs uses an input measure without considering mission effectiveness, which is an “output” measure. Instead, DOD should use cost-per-effect throughout the future-force development process.

Less is More
Mitchell Institute for Aerospace Studies

In a recent hearing, a senator posed this concern about operating cost of the F-35: “It comes down to an issue of numbers: The Air Force would like to see 1,763 F-35 aircraft, but if it costs $35,000 an hour, how can we afford that going forward?”

The senator missed the broader issue: To derive the same mission effects as an F-35 would require multiple, less-capable aircraft and higher risk to the mission and the aircrews. 

Indeed, William A. LaPlante, former assistant secretary of the Air Force for acquisition, warns of “overreliance on traditional units of assessment.” 

“While cost per flying hour is a common metric … such measures are far from infallible,” he said. “For example, we actually saw cost per flying hour decrease during sequestration because we were flying less. Modern operations—including fifth-generation technology and distributed family-of-systems approaches—require a far more rational and informing cost-capability analysis.”

If aircraft like the F-35 and B-21 can successfully meet the same mission goals with smaller teams and less support overhead, the cost to conduct specific missions will be less. As one U.S. fifth-generation fighter pilot explained, “Five to eight years ago, we would plan an entire force package of about 20 to 30 [fourth-generation] aircraft, all to maybe have a slim hope of taking down a modern surface-to-air (SAM) threat—just one SAM. Now, we train to accomplish the same mission with far greater certainty using just a few F-35s, while continuing to execute a host of other taskings.” 

On the first night of Operation Desert Storm, 20 F-117 Nighthawks struck 28 separate targets. Their ability to penetrate enemy air defenses without a large number of escort aircraft, coupled with precision strike technology, allowed the F-117s to destroy targets with just one or two bombs per target. By contrast, the first nonstealth aircraft attack package in that same war employed 41 planes—only eight of which dropped bombs—to hit a single target during the same exact time frame. Each nonstealth strike asset required multiple escort aircraft to jam hostile air-defense radars, suppress SAM threats, and counter enemy fighters. While the legacy, nonstealth strike aircraft were individually less expensive than the stealth F-117s, it took so many of them to accomplish a single task that the overall mission cost was far higher. The Nighthawks flew less than 2 percent of the air campaign’s combat sorties, while striking over 40 percent of the fixed targets. 

The Joint Capabilities Integration and Development System (JCIDS) uses key performance parameters (KPPs) to differentiate and compare competing systems during the acquisition process. Cost-per-effect should be one of these KPPs. Investing in new capabilities and concepts of operation that achieve objectives—such as delivering bombs on target, attaining air superiority, or gathering information across the battlespace—will yield the greatest cost-per-effect.

An F-4D Phantom from the 435th Tactical Fighter Squadron, Udorn Royal Thai Air Force Base, Thailand, armed with two GBU-10s. F-4s with such laser guided bombs were finally successful in taking down the notorious Thanh Hơa Bridge in Vietnam. USAF

How to Assess Cost-Per-Effect 

Cost-per-effect (CPE) assessments of future high-end capabilities should focus on peer conflict, following the direction of the National Defense Strategy, which emphasizes deterring—and if necessary, defeating—great power aggression. For future Air Force air superiority and strike combat systems, key factors should include: 

Precision. The more a discrete resource (i.e., kinetic bombing, cyber-attack, electronic warfare) can focus on a specific aimpoint to net a specific desired effect, the greater the chance of mission success. This streamlined approach reduces the need for redundant force support. 

Survivability. Ensuring that an aircraft can execute its tasks safely and return to its base ready for a future mission reduces attrition and the need for reserve aircraft. The more an aircraft can organically ensure its own survival within the existing battle network, without the need for air superiority and electronic warfare escorts, the more cost-effective the strike package. That frees other aircraft to be tasked with other priority objectives. 

Fifth-generation attributes. Stealth, electronic warfare, sensors, processing power, communication links, fusion engines, and real-time command and control are critical attributes that greatly increase force effectiveness and efficiency. Choosing not to invest in these capabilities is penny-wise and pound-foolish, driving significantly higher force structure requirements to achieve the same objectives.

Range and payload. Aircraft with greater range and payload capacity are more efficient solutions for missions that span significant distances, entail long in-flight loiter times, or involve attacking a large number of targets per sortie. 

Cost-per-effect assessments should extend to all domains when determining the most favorable business case for any combat objective. For example, investments in ground-based long-range fires should be evaluated in parallel with air- and sea-based alternatives, rather than within a ground-centric universe. With limited resources, only the most prudent solutions should be funded. 

The Case for Precision

Whether striking an aimpoint with a bomb, launching a missile against an air-to-air target, or securing a nonkinetic effect through electronic or cyber warfare, campaign objectives and overarching force efficiency will radically improve when a specific action can be tied to a desired effect. Nowhere is this better exhibited than with the emergence of precision weaponry in the Vietnam conflict. Between 1966 and 1968, aircraft dropping unguided munitions on specific targets averaged an accuracy rate—termed “circular error probable” (CEP)—of about 420 feet. That meant that half the bombs fell within 420 feet of their targets, and the other half impacted outside this radius. Air commanders employed large force packages of bomb-laden combat aircraft and multiple strike missions to ensure each target was destroyed. In other words, commanders used mass to make up for the lack of precision. Costs mounted in fuel, ordnance, and the loss of aircrews and aircraft. The Air Force had to sustain greater equipment and personnel margins to backfill losses. 

Starting in 1968, however, laser-guided and electro-optically guided munitions known as “smart bombs” could achieve CEPs of about 30 feet. The real-world impact of these new technologies was immense. The struggle to take down the Thanh Hóa Bridge in North Vietnam between 1965 and 1972 demonstrates the game-changing value of precision strike: The first U.S. Air Force attack on the bridge was launched on April 3, 1965, and consisted of 46 F-105s with unguided bombs, 21 F-100s providing air cover, two McDonnell RF-101s to execute bomb-damage photo reconnaissance, and 10 aerial tankers to refuel the strike package in-flight. The mission failed to destroy the bridge, and two U.S. aircraft were shot down, with another severely damaged. The following day, a strike mission launched with a similar force package; two more aircraft were lost, and the bridge remained standing. Over the following seven years, American combat aircrews flew 871 more sorties against the bridge, which remained standing. Another 11 aircraft were lost. Finally, on May 13, 1972, a strike package of just 14 F-4s with laser-guided bombs succeed in destroying the bridge. 

Today, precision guidance is a baseline assumption that has fundamentally changed how air campaigns are waged. As one Air Force pilot explained: “Precision targeting opens a host of options that otherwise would not be available with unguided munitions. You give senior leaders the ability to pursue dynamic targets in vehicles and on foot; strike targets in narrow alleyways or canyons; or even in specific rooms within a multitiered building.”

Adversaries have observed the power of precision and spent considerable time, energy, and resources countering it. They seek to degrade weapons guidance by jamming global positioning satellite signals, burying and hardening important facilities, and attempting to shoot down munitions in-flight. 

Airstrikes in peer-to-peer conflict will largely come down to knowing with great accuracy what to strike; having the means to rapidly transmit that information to relevant combat platforms and munitions; and to create multiple redundant pathways to achieve the desired effects in the face of sophisticated defenses. 

Thus, to truly understand the value and cost of any given weapon system, the officials judging the capability must fully understand how modern strike packages are assembled; alternatives to accomplish the same or similar missions; the cost of potential restrikes; and the risk and costs of incurring losses during a mission. As illustrated by the Vietnam conflict example, determining acquisition decisions on the cost of acquiring an aircraft alone risks choosing less-expensive capabilities that will actually drive up costs in combat. 

U.S. Air Force F-35A Lightning IIs assigned to the 388th and 419th Fighter Wings stage for combat training sorties at Hill Air Force Base, Utah, on July 14. The fighter wings are the Air Force’s only F-35A combat capable units. R. Nial Bradshaw/USAF

The Case for Survivability

The imperative to execute a mission, safely return to base, and fly again tomorrow is as old as air warfare itself. Aircraft shot down by an enemy must be replaced and new aircrews trained to take the place of those lost. Large-scale attrition robs commanders of the ability to secure multiple concurrent effects in a decisive fashion. At extremes, attrition can deprive commanders of the resources they need to win. 

This is exactly what happened to the 8th Air Force during World War II in Europe. In 1942 and 1943, stiff German resistance cost substantial American bomber losses. Without the capacity to supply the 8th Air Force with enough replacement aircraft and the training capacity to supply more pilots, leaders had to conserve resources rather than take the war to the enemy. As 8th Air Force Commander Gen. Ira C. Eaker later explained: “It became my duty to make certain that we did not, through unwise or careless or hasty action, sacrifice our whole force. We could have taken, say, our first 100 bombers at such a rate and against such [long] distance targets that we would have lost them all in 10 days, because on some of those targets we lost 10 percent on a mission. But I always said and reported to General [Hap] Arnold that I would never operate that force at a rate of loss which we could not replace.”

Stealth and other technologies developed in the Cold War to improve survivability in the face of Soviet-era air defenses. In Vietnam, the Air Force suffered high combat-loss rates because the enemy had defenses furnished by the Soviet Union. In Operation Linebacker II, in December 1972, the Air Force lost 15 B-52 heavy bombers in 12 days to the Soviet-built SA-2 SAM systems.

Less than a year later, Soviet-built air defenses cost Israel 102 combat aircraft from an inventory of 390 in the Yom Kippur War, which lasted less than a month. Of particular concern to U.S. defense officials, 32 of the downed aircraft were F-4 Phantoms, and 53 were A-4 Skyhawks, U.S.-built fighters that comprised a significant percentage of the U.S combat aircraft inventory at the time. Applying this loss rate to potential European conflict with the Warsaw Pact led U.S. leaders to conclude that a similar loss rate would expend the U.S. Air Force’s combat aircraft inventory after just two weeks. 

The U.S. needed to markedly increase combat-aircraft survivability. Thus began DOD’s impetus to develop stealth aircraft with outer mold line (OML) shaping, radar-absorbent coatings, and other technologies intended to prevent Soviet air defense systems from completing their find, fix, track, target, and engage kill chains. 

It worked. The first combat aircraft of this type, the F-117, suffered just one combat loss in its entire operational history against complex defensive systems that were far more advanced than those used during the Vietnam and Yom Kippur conflicts. The B-2 bomber, the second operational stealth aircraft fielded, has experienced no combat losses, despite regular use during some of the most dangerous phases of several post-Cold War operations, including the opening hours of conflicts when defenses were at peak lethality. 

Subsequent generations of stealth added powerful sensors and on-board processors to help pilots understand threats in the battlespace and manage their relative positions to reduce exposure to danger. Equipped with advanced electronic warfare technologies that can jam and deceive enemy defenses, they are today the envy of air forces around the world, and allies and adversaries, alike, aim to develop and field similar technologies.

Today, DOD air power inventories lack sufficient stealth capacity to challenge peer competitors. The U.S. Air Force has only 20 B-2s, 186F-22s, and less than 400 F-35s, compared  to several thousand nonstealth airframes. Today’s USAF fighter aircraft inventory is an 80/20 mix of nonstealth to stealth aircraft. 

The decision to prematurely curtail B-2 stealth bomber procurement at 21 airframes from an original plan for 132 aircraft, followed by the later decision to cap F-22 purchases at 187 aircraft, rather than 381, came about because of the perceived lack of threat. Looking back at the B-2 experience, former Secretary of Defense Robert  M. Gates explained, “By the time the research, development, and requirements processes ran their course, the aircraft—despite its great capability—turned out to be so expensive.” 

But, had the B-2 and F-22 decisions been informed by cost-per-effect capability assessments, would that have been the case? 

Using the Operation Desert Storm example, it took 19 legacy aircraft to achieve the same effects as one F-117. Procuring, manning, sustaining, basing, and operating 19 legacy aircraft costs far more than a single F-117. 

As potential adversaries field more advanced defensive technologies, the combination of stealth, networked all-domain sensors, situational awareness, and advanced electronic warfare capabilities will remain the baseline for U.S. air operations. The force-protection requirements for older, nonstealth aircraft designs are growing, and targets and other operational objectives accessible to them are rapidly diminishing. In future capability competitions, models must explore the value of a new capability against the value of seemingly “less-expensive” alternatives. Survivability must be a key part of this evaluation.

Fifth-Generation Technologies 

Fifth-generation stealth fighter aircraft such as the F-22, F-35, and eventually the B-21, are often criticized for their high cost. 

But those who have employed these aircraft see the advantages. “What was once nearly impossible has become commonplace with the advantages brought by fifth-generation aircraft like the F-35,”  noted one F-35 pilot. 

Three attributes explain why: survivability; mission performance; and the power to gather tremendous quantities of information, process it, fuse it with data from other sources, and then display highly intelligible and actionable knowledge in real time. 

“It used to be, as a fighter pilot that speed was life, and more was better,” said one pilot who has flown F-22, F-35, and fourth-generation fighter aircraft. “Today, information is life, and more is better. Period.” Added another F-22 pilot:  “A complete, comprehensive information picture of the adversary threat environment is what we need to best position ourselves to fight and win. Fifth-generation’s sensors, processing power, and fusion with other assets in the region does that. … It helps the pilot identify points of weakness in the adversary system by analyzing it as an integrated ecosystem.”

Legacy aircraft also feature a range of sensors and processing capability, but these systems are generally federated, presenting stovepiped information streams to pilots, rather than a fused and integrated single picture. Pilots must then interpret and fuse the streams themselves. Even with tremendous training and continual practice, pilot experience variances in the amount of information they can process in demanding combat scenarios. Improved sensors in the F-15EX or late block F-16s feature help, but the lack of stealth greatly limits when and where these aircraft can fly 

Fifth-generation aircraft generally fly in much smaller groups, requiring far less support from systems that degrade enemy defenses. By comparison, even the most capable, nonstealth combat aircraft require relatively large supporting packages of fighters to provide air superiority, adversary defense-suppression aircraft, and radar jamming systems. These force packages can often exceed two dozen aircraft. The acquisition cost for this array of aircraft, plus the cost of aircrew and associated maintainers, logistical demands, basing requirements, and basic consumables like fuel, makes this is a tremendously expensive proposition—and delivers a more vulnerable threat than do fifth-generation alternatives. In comparison, a small number of F-22s, F-35s, or B-21s are capable of accomplishing the same missions with far less support, and—all things considered—ultimately costs less to procure, sustain, and employ. 

The initial tranche of F-15EX “fourth-generation-plus” fighter aircraft will cost roughly $98.3 million each, with follow-on tails hopefully costing closer to $80 million per unit. The cost of the F-35, by contrast, is falling from $89.2 million for production Lot 11 to $77.9 million for Lot 14. Hence, F-35, though more advanced, is slated to cost about the same or less than the F-15EX. 

Flying hour costs are also similar. While the F-35A currently has higher operating costs than the anticipated F-15EX—$35,000 per flying hour versus a projected $27,000 for the EX,—cost-per-effect assessments favor the F-35A. The most significant cost drivers are associated with a combat aircraft’s sensors, processing power, and data links. For instance, if one inflates the unit cost of F-15Es procured in 1998 to 2020 dollars, they come in around $50 million per jet. The difference between the F-15E at $50 million and an F-15EX at $80 million is largely the result of the upgraded sensors, processing power, and data fusion. 

Efficiencies Do Matter: Range and Payload

Airframes with long range and sizable payload capacity may cost more to buy, but they also afford distinct operational efficiencies. For operations over vast distance, or where loiter time in the battlespace is important, or where there are a high number of targets, these efficiencies are particularly valuable. 

Between Aug. 8-20, 2014, in the opening stages of Operation Inherent Resolve (OIR) against the Islamic State group, the Navy flew 30 strikes with a nominal load of two 500-pound PGMs off the deck of the aircraft carrier USS George H.W. Bush. A single B-1 with unguided munitions or a single B-2 with guided munitions could have delivered more combat effects in a single sortie in a single day. Putting aside that aircraft carriers conduct a variety of missions other than strike, on a pure cost-per-effect basis for this missions, bombers were more efficient.

B-2s flew just 3 percent of the strike sorties during Operation Allied Force over Kosovo and Serbia, but struck 33 percent of the targets. B-1s flew 2 percent of the sorties, but delivered 20 percent of the bomb tonnage. In the opening phases of Operation Enduring Freedom over Afghanistan, USAF bombers few 20 percent of the sorties, yet dropped 76 percent of the munition tonnage. 

Comparing the rough cost-per-flying hour for one bomber versus 12 fighters, the cost to operate fighters is 371 percent higher. It is a simple matter of efficiency: 12 aircraft versus four consuming fuel, 12 pilots versus four aircrew in the bomber, plus sustainment costs. Factor in variables like long-range mission support, or the operating and personnel costs of an entire aircraft carrier battle group to host those fighters, and the difference only grows. 

In the Pacific theater, where distances extend dramatically, bombers can cover more ground without refueling—6,000 miles for the B-2; 7,500 for the B-1; and 8,800 for the B-52H. In comparison, fighters like the F-16C, F-15E, and F-18E/F offer an unrefueled range of only about 1,000 miles, depending on flight profiles and weapon loads. While reach can be extended with in-flight refueling, that adds to cost, operational complexity, and risk.

A prime example of this increased mission complexity and cost occurred in the opening days of Operation Enduring Freedom when theater air base availability limitations required F-15Es to fly from Kuwait to strike targets in Afghanistan. In an incredibly impressive display of airmanship, four F-15Es, each carrying nine 500-pound GBU-12s, two AIM-9Ms, and two AIM-120Cs flew a 15.5-hour mission from Kuwait to Afghanistan and back, spending nine hours over the target area. Each of the F-15Es refueled 12 times in the air. Yet two B-1s could have executed a similar mission carrying 48 GBU-31 2,000-pound JDAMs with the support of four to six aerial refuelings. That’s 12 more bombs on target by two fewer aircraft, with half the aerial refueling requirement: a more efficient operation by anyone’s calculus. 

Cost-per-Effect Assessments

The JCIDS process begins with a capabilities-based assessment. Procurement officials evaluate mission demands, desired capabilities, current capability gaps, and alternate solutions, producing in the process an Initial Capabilities Document (ICD), which scopes the solution that could best meet desired outcomes. From there, leaders can agree with the ICD document and press for a material solution; address the shortcomings through improved processes; or do nothing and make the most of existing options. When a material option is the favored course of action, leaders devise a Capability Development Document (CDD), creating a set of requirements and KPPs; this is when cost-per-effect matters the most. Models must evaluate how a system is expected to perform in given scenarios based upon specific factors: 

Weapons capacity is critical to determining cost-per-effect. The more aircraft needed to deliver an effect, the greater the cost. A single bomber can deliver the same or greater effects than a dozen F-16s: Dash Parham/staff

Number of effects that could be generated on a mission and supporting elements, such as protective escort aircraft and aerial refueling required.

Ability to team with other battlespace assets to yield collaborative effects.

Expected combat casualty rates.

Basing support requirements for the aircraft and its supporting enterprise, such as escort fighters, tankers, aircraft carriers, support ships, personnel, logistics requirements, and so on.  

This sort of evaluation would force strengths and weaknesses to emerge based on mission demands, allowing leaders to make informed decisions. As LaPlante explained: “An upfront analysis, much like was done at the front end of what became the B-21, is crucial in driving effective, efficient superior choices from the beginning of a program. … We need to adopt this approach.” 


While air power technologies and operational concepts evolved over the course of World War II, Airmen realized the theory of strategic attack from the air was valid. Over the ensuing decades, they remained committed to investing in mission tools that would better meet air combat requirements. In 1991, their success was dramatically demonstrated by the F-117 stealth fighters that struck across the breadth and depth of Iraq during Operation Desert Storm with disproportionate effects relative to nonstealth aircraft. Thanks to the protections afforded by stealth technology, precision weapons, and an innovative effects-based targeting strategy, these aircraft did not require fighter escort. 

With both sums normalized for 2019 dollars, the F-117, at a unit cost of $50,560,960, was dramatically more expensive to acquire than the B-17 with a unit cost of $3,383,450. However, where it took 863 World War II-era bombers to eliminate one target then, only 20 F-117s were used to strike 28 separate targets in just one hour, 50 years later. Using a simple cost-per-effect model and normalized dollar figures, the cost per target in 1991 was $36 million, down from $292 million per target during World War II. Add in the cost of fighter escorts, the larger crews for World War II bombers, the relative cost of spare parts, fuel, logistical support, and basing infrastructure, and the difference grows. 

Congress should require DOD to devise new measures to assess cost-per-effect for key mission areas and then implement such evaluations in the future force-development process. Such measures should be domain-, service-, and platform-agnostic, and instead focus on how best to achieve mission goals in future operations. 

Sir Frederick Handley Page, a British aviation pioneer, said: “Nobody has ever won a war by trying to run it on the cheap. Nothing is so expensive as losing a war by saving money. If you want the cheapest possible Air Force today, it is very easy to standardize on a whole lot of aircraft that will be of no use when the war comes.” 

The sanctuary that America enjoyed in the decades after the Cold War is over. The threats posed by Russia, China, and a host of other nations like Iran and North Korea are very real. As Senate Armed Services Committee Chairman Sen. Jim Inhofe (R-Okla.)  recently concluded, “I really believe we’re in the most dangerous situation we’ve been in this world in my lifetime.” 

B-17 Flying Fortresses during World War II. A cost-per-effect model using normalized dollar figures puts the cost-per-effect at $292 million per target during that war—and $36 million just 50 years later with precision weapons. George Letzer/American Air Museum/Imperial War Museum

Meeting those threats demands accurately aligning DOD’s weapon procurements with tactics, operational concepts, and warfighting strategy. Cost-per-effect must be harnessed as a tool by the Air Force, Department of Defense, OMB, and Congress to ensure tomorrow’s military personnel are equipped to meet the nation’s security requirements.                                                     

Lt. Gen. David A. Deptula, USAF (Ret.) is the dean of the Mitchell Institute for Aerospace Studies. Douglas A. Birkey is the executive director of Mitchell. This article is adapted from the Mitchell Institute’s research study, “Resolving America’s Defense Strategy-Resource Mismatch: The Case for Cost-Per-Effect Analysis,” which can be downloaded in its entirety at: