Re-Thinking the High-Low Mix, Part I: Origins Story


Recently, Sen. John McCain released a white paper entitled Restoring American Power. In it, he calls for the restoration of the U.S. military’s advantage:

Our military’s capabilities are also out of balance. On the lower end of the spectrum, we need greater numbers of more affordable, less advanced systems to fight terrorist enemies in permissive environments. On the higher end of the spectrum, as nation-state rivals can increasingly counter our military’s ability to project power, we need longer-range, more survivable platforms and munitions, more autonomous systems, greater cyber and space capabilities, among other new technologies. In this way, the joint force should be equipped with what is often called “a high/low mix” of capabilities.

The “high-low mix” is often invoked in the manner Sen. McCain describes. Although there has been no shortage of ink spilled by defense analysts, tacticians, industry executives, and policy wonks in discussion of the high-low mix, the term is widely used but still lacks a meaningful definition or historical understanding.

As a result, the high-low mix has lingered in a purgatory of relevance, and few examples in procurement exist that fit neatly within its binary construct. As an often-cited, seldom-executed framework, perhaps the issue is the constraints of the model itself. It is time to revive the spirit of the defense reform movement and adapt the high-low mix paradigm to the 21st century. But first one must understand what it is — and isn’t.

Origins of Resource Allocation

In the 1970s, retired Air Force Col. John Boyd, Thomas Christie, Franklin “Chuck” Spinney, and Pierre Sprey were key players of what became known as the defense reform movement. Widely credited with creating the anti-establishment movement to temper the defense industry’s addiction to high technology and increasingly complex weapon systems, the reformers became associated with introduction of the high-low mix — a strategic acquisitions play in which a small number of extremely capable aircraft (high) coupled with a large number of less expensive aircraft (low) had the cumulative effect of a much larger force. By the late 1970s, this became a conceptualization of airpower and subsequently manifested as an aircraft procurement strategy that provided a reference point most in the field accept in theory. Yet 40 years later, examples of this in practice have been the anomaly — not the strategy.

The principles that underpin the reformer’s high-low force mix were born out of lessons observed during a period spanning the early 1960s to the mid-1970s. It started with the Air Force procurement strategy behind the “century series” aircraft. Driven by the sobering realities of near-technological parity over the skies of Korea, over six years the Air Force procured seven different types of aircraft built by five manufacturers  — a mix of fighter-bombers (F-100,  F-101A,  F-105) and interceptors  (F-101B, F-102, F-104, F-106). They were all designed as iterative high-end platforms and shared virtually nothing in common.

This “parity apprehension” was raised again in 1967 following the unveiling of the MiG-25 Fox Bat, a fighter aircraft equipped with the world’s largest missiles and capable of Mach 3 at 70,000 feet. It could presumably challenge the previously untouchable SR-71 and the in-development XB-70 supersonic bomber. This ultimately shaped the Air Force response in the form of the F-15 Eagle program and its Mach 2.5 requirement. However, by the time F-15 development began, the Air Force found itself staring at two divergent paths. It was chasing more advanced equipment that increased procurement costs and overruns, but also was slowly seeing its aircraft inventory diminish. Between 1957 and 1967, the Air Force inventory of bombers and fighters shrunk by 17 percent. By 1977, when the reformer movement was growing, this had been slashed another 26 percent.

In its simplest form, the high-low mix is a nod to an economic reality: the law of scarcity. Throughout history, military campaigns have always dealt with the tyranny of distance and the frustration of geography. Although the speed of maneuver has increased, the world remains a very big place. Even in the tidy confines of a state-on-state armed conflict, there are more fighter coverage gaps than there are four-ship formations out there to fill them with. The idea that a comparatively larger number of low-cost forces can picket, distract, channelize, and otherwise shape a battle favorably against comparatively high-end friendly forces is nearly as old as warfare itself — skirmishers working with heavy infantry, heavy infantry with cavalry, etc.

If we flip the construct, the idea that a small number of high-end assets can increase the utility of a large number of less-capable assets is the basis for the oft-touted “force multiplier,” and is also applied in non-military endeavors. A hospital has fewer surgeons than nurses on its staff, but the combination of the two is highly effective and resource-efficient.

Thus, the high-low mix may be most appropriately thought of as a two-way relationship. Properly implemented, both parts make the whole better. In this regard, the high-low mix is a binary construct. Military procurement programs that tempt fate by spanning the valley between the high-end and the low-end are replete with compromises in range, payload, speed, survivability, cost, complexity, and sustainability — not to mention the challenges of currency and proficiency operators must contend with.

Anything You Can Do, I Can Do Better, Except for That

Underpinning the ideas of the high-low mix are a few critical assumptions which, like the assumptions that support all conventional wisdom, should be revisited from time to time to validate the experience garnered. As the saying goes, wisdom comes from experience, but experience is often the result of the lack of wisdom.

At first glance, the high-low mix would seem to grade systems based on performance and then makes the reasonable assumption that aircraft cost is directly related to said performance. Yet Boyd, Christie, Spinney, and Sprey more precisely questioned the wisdom of the Pentagon’s pursuit of ever-more-complex weapon systems. In particular, their criticisms of what became the F-15 were instrumental in the development of a complementary lightweight fighter, the F-16. The F-15’s reliance on radar-guided missiles (complexity) was held up in sharp contrast to the highly maneuverable F-16 paired with heat-seeking missiles (simplicity).

Spinney’s “Defense Facts of Life,” which came along after these fighter programs, is a classic that bears re-reading today. He astutely noted that “advanced technology and high complexity are not synonymous.” Viewed through Spinney’s lens, the high-low mix is more about balancing complex systems with robust multi-domain performance but which historically offer lower reliability (the “high”) when compared to simpler, specialized systems (the “low”) — the latter of which may in fact outperform their high-end counterparts in specific mission sets. Today, this is best exemplified in the A-10 versus F-35 close air support (CAS) debate. Despite the now-defunct effort to retire the A-10 in the midst of the 2013 fiscal calamity, the A-10 bests the F-35 replacement in cost, payload, loiter time, resiliency, austere forward basing potential, firepower, and ironically — in CAS-centric electro-optical sensors. Yet, the F-35 is the most expensive, complex, and largest acquisitions program in history.

Augustine’s Singularity

In 1986, noted aerospace executive Norman Augustine published a now famous analysis of the cost of U.S. military aircraft. In it, he revealed exponential growth such that,

In the year 2054, the entire defense budget will buy just one tactical aircraft…which will have to be shared by the Navy and the Air Force 6 months each year, with the Marine Corps borrowing it on the extra day during leap years.

This prophecy has largely played out, as shown by an Economist article in 2010. Augustine even revisited his prediction in 2015 . After 30 years, his trademark style of incisive humor was intact. As an unfortunate corollary of Augustine’s law, the sheer variety of designs of aircraft in the U.S. inventory (and the world) has been on the decline. As an example, compare the carrier air wing of the 1980s with that of the near future. Tomorrow’s carrier air wing will contain 28 percent fewer aircraft and concentrate them in half as many types. The same rationale of consolidation was the impetus for pitching the A-10 retirement in 2013.

Of course, this is aimed at simplifying logistics and putting more resources toward maintaining the readiness of increasingly complex aircraft by simply supporting fewer types of aircraft. Concurrently, the number of companies required to build this diminishing variety of aircraft has not unexpectedly shrunk as well. Frank Kendall, the out-going Pentagon acquisition chief, recently warned that the defense industry has “over-consolidated” and has “reduced the number of new ideas and innovations pitched” to the department.

However, the ever-shrinking base of new aircraft procurements, astutely predicted by Norm Augustine 30 years ago, is but a symptom. 

Misunderstanding the Mix

In these origins, we find one of the biggest misunderstandings of the high-low mix. Today, it is generally accepted that high-end platforms have comparably high cost and high complexity. However, the reform movement was about breaking this association apart and challenging the notion that performance and complexity be dependent variables in the force structure formula.  Whereas high-performance niche platforms could be had at low cost, these would be augmented by platforms of greater complexity that could span several niches of a mission (or more than one mission).

The high-low paradigm receives nearly universal agreement but has rarely, if ever, been implemented during the course of subsequent procurement programs.

In the next part, we will apply the classic high-low paradigm discussion to the U.S. Air Force in order to highlight the lack of a true acquisition-equivalent of grand strategy, a misunderstanding of the dynamics of the evolution of warfare, and the inability of both procurement officials and industry to field high-performance, low-complexity designs.


Scott Bledsoe is the President of Blue Force Technologies, a North Carolina-based aerostructures and aircraft R&D firm.  He has led novel design / build activities for aircraft in the VTOL, supersonic, and low-observable regimes, as well as space launch systems.  The views expressed are his own.

Maj. Mike “Pako” Benitez is an F-15E Strike Eagle Weapons Systems Officer with over 250 combat missions spanning multiple deployments in the Air Force and Marine Corps. He is a graduate of the U.S. Air Force Weapons School and a former Defense Advanced Research Agency (DARPA) fellow. The views expressed are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government.

Image: U.S. Air Force