Innovation and Air Dominance: Human-Machine Combat Teaming, A SoS Solution to Air Superiority - Part II

Image 4: Possible SoS solution to air superiority circa 2025. Image Credit: Matt

Lt. Gen. James M. Holmes, Deputy Chief of Staff for Strategic Plans and Requirements, and other senior USAF officials have advocated for a systems of systems (SoS) solution to U.S. air superiority which would grant greater modularity, lower cost, and acquisition speed when compared to a traditional follow-on platform approach. Ultimately a SoS approach to air superiority has the potential to deliver on many of the aforementioned benefits above, but a manned sixth generation follow-on platform is still required to ensure a robust air superiority capability following a lengthier acquisition cycle. The debate within the USAF for an SoS approach to air superiority has been influenced by broader DoD discussions of the third offset strategy and human-machine combat teaming. 

Human-machine combat teaming is an integral aspect of the third offset strategy which includes not only greater use and development of autonomous and semi-autonomous systems but also the organization of data and battlefield networks to facilitate greater situational awareness and human decision making.[1] Deputy Defense Secretary Robert Work cites the Army’s MUM-T system, in which an AH-64E attack helicopter can control an MQ-1C Grey Eagle, as an example of a highly capable human-machine combat system predating the third offset strategy. The MQ-1C’s remotely piloted vehicle (RPA) sensors enable the AH-64E to fire its hellfire missiles at longer ranges than otherwise possible using only the AH-64E’s sensors.[2] The Avatar/ Skyborg program by the Strategic Capabilities Office (SCO) is frequently touted as a representative example of expected future human-machine combat teaming, the Avatar program is often referred to as the “loyal wingman” concept by the USAF.  The Avatar program seeks to modify older fourth generation aircraft into unmanned systems, such as the QF-16 target drone, and pair them with manned 5^th generation assets. The unmanned systems would act as a force multiplier for manned assets by carrying additional weapons which would be directed by the sensors of other assets in a battlefield network.

Colonel Michael W. Pietrucha’s concept for a semi-autonomous force multiplier unmanned combat aerial vehicle (UCAV) outlined in, The Next Lightweight Fighter, provides a useful intellectual framework from which to conceptualize the role and requirements of the loyal wingman concept,

The UCAV will not replace the manned fighter aircraft – we cannot build a control system to replicate the sensing and processing ability of trained aircrews. Nevertheless, UCAVs may play a valuable role as a supplementary system. Not remotely piloted aircraft [RPA], they will operate semiautonomously, serving as literal wingmen of limited capabilities. We can build the technology to fly an aircraft and execute the preprogramed routines. The ‘brains’ of the operation will remain the nearby human, who needs only to tell the UCAV what to do and (mostly) forget about it.[3]

The UCAV would not be a dogfighter in the traditional sense. Rather, the UCAV would act as a “missile truck” for 5^th generation assets given the limited internal carriage of weapons in the F-22 and F-35. Therefore, the design can sacrifice many of the design attributes associated with high-end maneuverability in favor of payload, endurance, and range. Pietrucha outlines three modes from which his proposed F-40 Warhawk UCAV could operate: autonomous, semi-autonomous, and cooperative. However, Pietrucha’s vision of autonomous capabilities are relatively modest such as basic aviation capabilities related to navigation of predesignated locations and weapons employment against fixed targets. In the Air Force publication, Autonomous Horizons, the USAF Office of the Chief Scientist mirrors many of Pietrucha’s technical feasibility reservations regarding fully autonomous combat aircraft.[4]

Image 5: BVR detection and engagement ranges between the F-35 armed with an AIM-120D vs. a Su-30MK with a R-77M-PD. The length between points is to scale with real world figures, the width is not. Its also important to note the maximum kinematic range of each missile is never the actual effective range of the missile which is contingent upon its launch point with corresponding airspeed and altitude of launch platform as well as its position or aspect relative to the maneuvering target among other factors. Even with all these factors in consideration, the U.S. still maintains a substantial advantage in BVR as a result of low observability and more powerful AESA radars. Image Credit: Matt

            While a fully autonomous within visual range (WVR) capable UCAV could conceivably outmaneuver and outperform human pilots by virtue of lacking biological limitations, the technological, legal, and financial barriers are too significant to realistically field the system within the next decade. Furthermore, even if all the aforementioned challenges to autonomy were solved, the USAF would likely fiercely oppose any unmanned fighter on the basis of institutional-cultural grounds as demonstrated by the resistance to adopting the much more modest proposal of arming the MQ-1.[5] As an institution, the USAF has placed enormous faith in the longevity of the U.S.’ comparative advantages in stealth and avionics which enable “first shot first kill” capability. Unmanned systems have the capacity to solidify the U.S.’ comparative advantage in BVR engagements but will be unable to fulfill the WVR classic dogfighting requirement that traditional follow-on platforms provide. A manned sixth generation fighter is still necessary. U.S. strategic competitors have made significant progress in eroding the U.S.’ BVR advantage by fielding in theater numerically superior forces with both high missile loads and effective jamming to reduce the pk of U.S. radar guided missiles. A manned sixth generation platform provides a hedge against technological uncertainty by providing historically relevant capabilities in the context of the measure-countermeasure competition between the U.S. and potential adversaries in BVR technologies. While the USAF’s goal is to produce a sixth generation platform with an IOC by 2030, given numerous historical examples such as the F-35 program, an IOC by 2030 is likely optimistic. A low cost SoS solution incorporating a loyal wingman UCAV to smooth the transition between fifth and sixth generation platforms would be invaluable for the USAF.

Image 6: The loyal wingman concept is in many ways reminiscent of Lockheed Martin's modular optionally manned Saber Warrior concept. Image Credit: Lockheed Martin. 

The loyal wingman concept and other forms of human-machine combat systems naturally fit within a broader SoS architecture in terms of concepts of operation. SoS refers to a organizational structure in which multiple specialized independent systems are utilized in conjunction with one another to generate synergistic effects which are greater than the sum of independently operating those systems. SoS solutions are contrasted by platform centric solutions which seek to field highly capable multi-function platforms capable of undertaking a wide spectrum of missions.[6] Advocates of the SoS approach argue the more specialized and limited requirements for each individual component within the SoS decreases cost and technical challenges. Additionally, the low cost and technical risk of each component enables rapid replacement and greater agility when upgrading the SoS. In an environment of approximate technological parity, the ability to quickly upgrade and reconfigure systems in order to counter adversary developments is invaluable. Rather than defeating an adversary outright as a result of superior technology, the pronounced aversion to high technical risk platforms has guided the service to place a greater emphasis on concepts of operation and the integration of several different mature but promising technologies, as SoS can, to deter and defeat near-peer competitors.

At a CNAS event in 2015, Deputy Secretary Robert Work remarked on the current strategic environment with respect to integrating existing technologies into operational concepts: “…this is much more like the inter-war period, where everything was available and all you had to do -- it was the competitors who put the components together into operational and organizational constructs that gave them the advantage.”[7] The inter-war period and early Cold War demonstrate the feasibility of SoS with respect to two foundational concepts of peacetime innovation: (1) superior concepts of operation can result in decisive battlefield results over a technically and numerically matched adversary and (2) effective management of technological uncertainty is achievable through extensive prototyping and diversifying investment in several technologies. For example, the Wehrmacht’s success in the battle of France was determined not by technological superiority but by its organizational structure and superior understanding of armored warfare developed in the interwar period. In May 1940, French and British tank forces not only had numerical superiority over the Germans, but also allied tanks often had superior firepower and protection relative to German tanks.[8] The U.S. development of guided missiles between 1945 and 1955 serves as a model in which technological uncertainty was mitigated through extensive prototyping of multiple systems, but procurement was deferred until other uncertainties – such as political considerations, were resolved.  The diversification and risk mitigation of several technologies has a high degree of applicability to a SoS approach to air superiority. [9] With the aforementioned principles to peacetime innovation in mind, the following recommendations would enable the USAF to field a SoS approach to air superiority which would significantly augment existing platforms within a relatively short period between 2025 and 2030.

The focus of this SoS approach to air superiority is to seek promising existing technologies and integrate them in such a way that the U.S. can quickly produce new capabilities at a relatively low cost. All the systems discussed are either operational, in the midst of the procurement process, or incorporate mature technologies but no procurement decision has been approved. The approach seeks to solve as many of the six aforementioned challenges to air superiority the U.S. will face in the Asia-Pacific between 2025 and 2030. The following are the major components in the proposed SoS solution to air superiority: the miniature air launched decoy (MALD), SACM, loyal wingman, and 5^th generation fighter platform. As MALD, 5^th generation platforms, and SACM have all been approved from a development perspective, this paper will focus on the development and integration of a loyal wingman aircraft to the other SoS components. An analysis of the role of the loyal wingman and its associated benefits and limitations will be followed by an analysis of recommendations regarding how to transition the SoS concept into an operational reality.

Image 7: SoS components. The design characteristic of SACM, that it can fit on a SDB rack, is inferred from Lockheed Martin's CUDA concept which competed and ultimately lost against Raytheon's SACM concept which has not been revealed at this time. Image Credit: Matt

            The rapid pace at which the loyal wingman would need to be developed necessitates fairly conservative requirements to boost acquisition agility. The core requirements of any force multiplier type UCAV are: semi-autonomous control via F-35 and F-22, air-to-air missile storage capacity, reduced radar cross section, extended range and endurance, and low cost and technical risk. The use of a secure resilient data link would enable 5^th generation platforms to act as forward command and control (C2) assets by directing larger formations of force multiplier type loyal wingman UCAVs. The superior avionics and integration of data via fused sensor inputs of 5^th generation fighters naturally facilitates this C2 role. Over the skies of Syria, F-22 pilots regularly guide and direct other assets given their superior situational awareness of the battlefield.[10] This SoS approach would expand upon those C2 capabilities by granting the F-22 and F-35 pilots control over UCAVs. The following is a hypothetical scenario which demonstrates the utility of a SoS solution to air superiority featuring MALD, SACM, the loyal wingman, and 5^th generation platforms:

1. 24 MALDs fly towards an adversary IADS and utilize their onboard signature augmentation subsystems to mimic a formation of F-15s
2. An adversary formation of 20 Su-30s detects the decoys via radar and fires a salvo of R-77 BVR radar guided missiles
3. A formation of 4 F-35s operating in a low electronic signature state detect the radar emissions of the Su-30s utilizing their geolocation apertures and determine their position via time difference of arrival (TDOA)
4. The lead pilot in the F-35 formation commands 8 nearby low observable UCAVs to fire their payload of 48 SACMs in lock-on after launch (LOAL) mode
5. The lead F-35 pilot guides the SACMs to the approximate location of the Su-30s via a two-way data link with each missile
6. The terminal seekers of the SACMs activate when in close proximity to the Su-30 formation, the use of LOAL and a two-way data link gives the Su-30s the minimum possible time to detect the missiles and employ countermeasures thereby maximizing the missile’s pk

Of the six major aforementioned challenges with respect to establishing air superiority in the Pacific, a SoS approach has the potential to solve the reduced missile storage and pk issues as well as both mitigating strain on aerial refueling assets and reducing the PRC’s regional numerical superiority. The service does not have time to initiate a new clean-sheet design if it seeks an operational capability between 2025 and 2030, an existing design with modification potential must be selected. Two possible designs meet the desired requirements for the loyal wingman: a modified QF-16 and Predator-C Avenger.

Author's Note: Part III: Loyal Wingman Options and Procurement Strategy

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[1] Sydney J. Freedberg, Jr., “People, Not Tech: DepSecDef Work On 3rd Offset, JICSPOC”, February 2016. http://breakingdefense.com/2016/02/its-not-about-technology-bob-work-on-the-3rd-offset-strategy/

[2] Richard Whittle, “MUM-T Is the Word for AH-64E: Helos Fly, Use Drones “, January 2015. http://breakingdefense.com/2015/01/mum-t-is-the-word-for-ah-64e-helos-fly-use-drones/

[3] Col Michael W. Pietrucha, "The Next Lightweight Fighter", Air & Space Power Journal, August-July 2013.

[4] United States Air Force Office of the Chief Scientist, "Autonomous Horizons", June 2015. http://www.af.mil/Portals/1/documents/SECAF/AutonomousHorizons.pdf?timestamp=1435068339702

[5] Richard Whittle, Predator, (Henry Hold and Company, 2014).

[6] John Shaw, “System of Systems Integration Technology and Experimentation (SoSITE)”. http://www.darpa.mil/program/system-of-systems-integration-technology-and-experimentation

[7] Robert Work, “Deputy Secretary of Defense Speech”, December 2014. http://www.defense.gov/News/Speeches/Speech-View/Article/634214/cnas-defense-forum

[8] Steven J.Zaloga, PANZER IV VS CHAR B1 BIS France 1940, Osprey Publishing, 2011.

[9] Stephen Peter Rosen, Winning the Next War, (Cornell University Press, 1991).

[10] Lolita C. Baldor, “F-22 Raptor Ensures other War-Fighting Aircraft Survive Over Syria”, July 2015. http://www.military.com/daily-news/2015/07/21/f22-raptor-ensures-other-war-fighting-aircraft-survive-syria.html

Innovation and Air Dominance: 2025 and Beyond - Part I Intro

Image 1: F-22s from the 27th FS transit from Wake Island to Anderson AFB, Guam. Image Credit: USAF, Captain Gary Wallace.

Author's Note: This article series will discuss the anti-access threat environment the U.S. is likely to encounter post-2025 and advocates for both a near-term systems of systems (SoS) solution to bridge the gap between current 5th generation and future 6th generation fighters.

Air Superiority – A Foundational Element of American Security

Air superiority is a foundational objective to not only all other United States Air Force (USAF) core missions such as space control, intelligence, surveillance, and reconnaissance (ISR), rapid mobility, global strike, and command and control, but also air superiority is critical to the success of the joint force and a core tenant of the American way of war.[1][2] In the post-Cold War era, the USAF and U.S. policymakers have become accustomed to uncontested freedom of action across multiple domains in permissive environments such as Iraq and Afghanistan. The lopsided success of coalition forces against the integrated air defense systems (IADS) of Iraq in 1991 and Libya in 2011 are attributable to both technological and training advantages of coalition forces. The overwhelming capabilities of American airpower have become associated as a uniquely American capability to destroy an adversary’s means to wage war at minimal cost. The formidable reputation of American air power thereby serves as a powerful deterrent.[3] However, the technologies which form the basis for the U.S.’ current qualitative military edge provided by the second offset strategy have proliferated to U.S. strategic competitors such as the People’s Republic of China (PRC) and the Russian Federation. Anti-access/area denial (A2/AD) threats severely constrain the U.S. ability to project power, maintain freedom of action, and secure use of the global commons which are historically integral U.S. national security objectives.[4]

The PRC’s A2/AD strategy in particular threatens many of the core national military and security objectives outlined by the Joint Chiefs of Staff such as: protecting vital economic interests, U.S. allies, and U.S. overseas territories.[5] The combination of the evolving threat environment and the 15 to 20 year traditional weapons acquisition process has elevated the sense of urgency within the USAF to rapidly field capabilities to address the threat environment to the joint force.[6] This paper will propose (1) fielding a modular low cost systems of systems (SoS) approach to air superiority between 2025 and 2030 and (2) accelerating the USAF’s sixth generation F-X program to replace the fifth generation F-22 in the dedicated high-end air dominance role with an initial operational capability (IOC) no later than 2035. An analysis of the expected future threat environment will be provided prior to an examination of the SoS proposal, the F-X program, how the USAF could accelerate the program, budgetary considerations, and relevant counter arguments.

The A2/AD Threat Environment of 2030

Image 2: PRC A2/AD systems. Image Credit: CSBA 

The People’s Liberation Army (PLA) was largely a poorly trained, Soviet equipped, and manpower centric defense force for much of the 1970s and 1980s. The decisive results of the Persian Gulf War surprised many PRC strategic planners and contributed towards an internal belief within the PLA that it was insufficiently prepared to confront the U.S. and that a conventional force-on-force engagement with the U.S. was not a viable option.[5][6] The general deterioration of Sino-U.S. relations following Tiananmen Square in 1989, the Third Taiwanese Strait Crisis in 1996, and the U.S. bombing of the Chinese embassy in Kosovo in 1999 all provided the impetus for China's development of its current A2/AD strategy and transformative military modernization effort.[7] In 2015, the PRC spent $215 billion on its military making it the second largest source of global military expenditures after the U.S.[8]The PRC’s modernization effort more broadly is contextualized by its national objectives set by the Chinese Communist Party (CPP):

·         Perpetuating CCP rule;

·         Sustaining economic growth and development;

·         Maintaining domestic political stability;

·         Defending national sovereignty and territorial integrity; and

·         Securing China’s status as a great power and, ultimately, reacquiring regional preeminence[9]

The PRC leadership has clearly shown its preference for asserting regional hegemony by gradually altering the status quo by coercing U.S. allies below the threshold of overt military force.[10] However, the PRC actively seeks “counter intervention” capabilities (反侵入 or 反干涉) which facilitate PRC regional hegemony by denying the U.S. the ability to intervene on behalf of threatened U.S. allies such as the Philippines, Japan, or Taiwan in the event of hostilities.[11] To constrain US power projection near its shores, the PRC has implemented a host of A2/AD systems including: sea mines, anti-ship cruise missiles, electronic and GPS jamming, submarines, anti-satellite weapons, conventional land attack and anti-ship ballistic missiles, and extensive surface to air missile systems (SAM) networked with air power.[12] These systems collectively limit how close US forces can safely operate in proximity to the PRC. The PRC’s acquisition of advanced SAMs such as the HQ-9 and advanced fifth generation fighters such as the J-20 and J-31 are a particularly significant challenge to U.S. regional air power.

While the F-22 provides unmatched air superiority capabilities, the original requirements for the F-22 are becoming less relevant for the Asia-Pacific threat environment of 2030, particularly its limited range. The original Advanced Tactical Fighter (ATF) program requirements called for a fighter which could penetrate Soviet and Warsaw Pact airspace from a network of nearby bases in Western Europe.[13] Any sixth generation solution to bolster U.S. air superiority capabilities in the not too distant future of 2030 will face the following challenges with respect to the Asia-Pacific region in support of the Administration’s pivot:

1. The PRC is expected to retain an in theater regional numerical superiority over the U.S. in terms of deployed fighter aircraft even with a surge force deployed from the continental U.S.[14]
2. Air superiority requires secure bases close to the desired operational area. The significant distances between U.S. and allied facilities in the Pacific relative to key areas of interest such as the Strait of Taiwan, East China Sea, and South China Sea will cripple sortie generation rates and would put a tremendous strain on U.S. tanker assets[15]
3. Air bases close in proximity of China, such as Kadena, are not only within range of China’s short to medium range conventional ballistic missiles, but also feature few hardened aircraft shelters and exposed above ground fuel depots[16]
4. The emergence of high quality low cost digital radio frequency memory (DRFM) jammers has significantly degraded BVR radar guided missile probability of kill (pk) performance while U.S. fifth generation aircraft have a reduced missile load due to their internal carriage of weapons for the purposes of low observability
5. Increasingly capable very high frequency (VHF) radars will degrade the effectiveness of X and S-band optimized stealth aircraft, such as the F-22 and F-35, into the late 2020s to 2030s. VHF radars do not provide target quality track data and could at best serve as early warning systems to cue other assets[17]

Image 3: Approximate distances of U.S. and allied air bases in the Western Pacific relative to key areas of interest. The F-22’s unrefueled internal stores only combat radius at is 410 nautical miles (nm) with a ferry range of at least 820 nm: blue = locations with no inflight refueling required per sortie, yellow = at least one per sortie, red = at least two per sortie.[18][19][i]

In response to the evolving threat environment, the USAF continues to work with its sister services to devise means to counter A2/AD capabilities under the Joint Concept for Access and Maneuver in the Global Commons (JAM-GC) operational concept, formerly Air-Sea Battle.  JAM-GC is not a war plan nor is it directed at any one country, rather JAM-GC’s purpose is to provide an operational level description on how the joint force will gain and maintain freedom of action across all domains in the global commons. Attaining freedom of action is necessary as it is the precursor to all other operations including deterrence and power projection.[20] Under JAM-GC, the joint force will conduct networked integrated operations capable of attacking in-depth to disrupt, destroy, and defeat adversary forces.[21]  

The USAF will comprise a core component of the joint force’s collective capability to attack in-depth through a highly contested A2/AD zone with a mixed force of F-35s, B-21s (LRS-B), and sixth generation F-X fighters. Without a sixth generation F-X to provide air superiority, the ability to attain freedom of action for the joint force is compromised. The F-X’s extended range, deep magazine capacity, and broadband all aspect stealth will enable the F-X to survive in the most contested A2/AD environments and execute key air superiority and destruction of enemy air defense (DEAD) missions. However, between late 2015 to early 2016, the USAF has grown increasingly noncommittal towards pursuing an F-X platform given the immediate needs of the service relative to the acquisitions process.[22] The hesitation to commit to an F-X platform within the USAF coincides with the broader Department of Defense’s (DoD) third offset strategy, a competitive strategy which seeks to maintain the U.S. military’s qualitative technological superiority over near-peer adversaries.

Author's Note:  PART II: Human-Machine Combat Teaming: A SoS Solution to Air Superiority

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[1] USAF, “Air Force Core Missions”, August 15, 2013.  http://www.af.mil/News/ArticleDisplay/tabid/223/Article/466868/air-force-core-missions.aspx

[2] Colin S. Gray, “The Air Power Advantage in the Future”, December, 2007. http://aupress.maxwell.af.mil/digital/pdf/paper/ap_0002_gray_airpower_advantage_future_warfare.pdf

[3] Eliot A. Cohen, “The Mystique of U.S. Air Power”, Foreign Affairs, Jan. – February, 1994, pp. 109-124. 

[4] William J. Perry, et al, “Ensuring a Strong U.S. Defense for the Future – The National Defense Panel Review of the Quadrennial Defense Review”, 2014.

http://www.usip.org/sites/default/files/Ensuring-a-Strong-U.S.-Defense-for-the-Future-NDP-Review-of-the-QDR_0.pdf

[5] “Robert Farley, What Scares China's Military: The 1991 Gulf War”, November 24, 2014. http://nationalinterest.org/feature/what-scares-chinas-military-the-1991-gulf-war-11724

[6] Sam J. Tangredi, Anti-Access Warfare: Countering A2/AD Strategies (Naval Institute Press: 2013).

[7]Andrew S. Erickson, “Chinese Anti-Ship Ballistic Missile (ASBM) Development: Drivers, Trajectories and Strategic Implications”, May 2013.

http://www.andrewerickson.com/wp-content/uploads/2014/01/China-ASBM_Jamestown_2013.pdf

[8] Jon Gambrell, “Global military spending nearly $1.7T amid Mideast conflicts”, April 4, 2016.   http://bigstory.ap.org/article/d9a7ab6fb5f4430db369b80c696e62fb/global-military-spending-nearly-17t-amid-mideast-conflicts

[9] “Annual Report To Congress Military and Security Developments Involving the People’s Republic of China 2015”, Department of Defense, 2015. http://www.defense.gov/Portals/1/Documents/pubs/2015_China_Military_Power_Report.pdf

[10] Truong Minh Vu and Ngo Di Lan, “Flexible Response To Deter In The South China Sea”, April 7, 2016.

http://amti.csis.org/flexible-response-deter-south-china-sea/

[11] Timothy Heath and Andrew S. Erickson, “Is China Pursuing Counter-Intervention?”, The Washington Quarterly, Fall 2015.  https://twq.elliott.gwu.edu/sites/twq.elliott.gwu.edu/files/downloads/TWQ_Fall2015_Heath-Erickson.pdf

[12] Matthew J. Jouppi, “America's Sixth Generation Fighters: The F-X and F/A-XX”, February 18, 2015. http://manglermuldoon.blogspot.com/2015/02/americas-sixth-generation-fighters-f-x_4.html

[13] Carlo Kopp, “The Advanced Tactical Fighter [YF-22 and YF-23]”, last modified 2005. http://www.ausairpower.net/TE-ATF-91.html

[14] John Stilton and Scott Perdue, “Air Combat Past, Present, and Future”, August 2008.  https://www.defenseindustrydaily.com/files/2008_RAND_Pacific_View_Air_Combat_Briefing.pdf

[15] Ibid.

[16] Ibid.

[17]  Dave Majumdar, “Chinese and Russian Radars On Track To See Through U.S. Stealth”, July 2014. https://news.usni.org/2014/07/29/chinese-russian-radars-track-see-u-s-stealth

[18] Google Maps Data, 2016.

[19] Department of Defense, “Selected Acquisition Report (SAR) The F-35 Joint Strike Fighter (JSF), Mary 18, 2015. http://fas.org/man/eprint/F35-sar-2016.pdf#page=16

[20] Terry S. Morris, et al., “Securing Operational Access: Evolving the Air-Sea Battle Concept”, February 11, 2015

http://nationalinterest.org/feature/securing-operational-access-evolving-the-air-sea-battle-12219?page=2

[21] CDR John Callaway, “THE OPERATIONAL ART OF AIR-SEA BATTLE”, July 18, 2014.

http://cimsec.org/operational-art-air-sea-battle/11913

[22] James Drew, “USAF backs off sixth-gen 'fighter' in quest for air supremacy”, April 2016. https://www.flightglobal.com/news/articles/usaf-backs-off-sixth-gen-fighter-in-quest-for-air-423994/

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[i] Total trip distance is twice the distance from the area of interest relative to the base. The number of full aerial refueling required is calculated by dividing total trip distance by ferry range. This is an approximate figure as the aircraft will have extra fuel upon reaching its maximum combat radius to conduct its mission i.e. patrol an area before returning to base.