The United States Air Force is reportedly considering retiring its F-15 Eagle air superiority fighters after over 40 years of service, with the ageing platforms costing too much to maintain and increasingly considered obsolete in the face of threats by near peer adversaries. A report by military officials to the U.S. Congress in March 2017 indicates that this option is being actively considered, and the Air Force has since taken a number of steps indicating the likelihood of this option being followed up including cancelling upgrades for the Eagle fleet - essential to keep the platforms viable but a waste of funds should they be imminently about to retire. While the Air Force had planned to procure new electronic warfare equipment for the F-15 fleet, particularly key to enhancing the platform’s survivability considering its lack of stealth capabilities, a report declassified on May 21st 2018 showed that this critical but highly costly upgrade had been canceled. A report by the Defence Department’s inspector general stated regarding the significance of this upgrade, set to cost approximately half a billion dollars to apply to the entire Eagle fleet: “Using the F-15C aircraft without EPAWSS will limit the warfighter’s ability to detect and identify air and ground threats, employ counter-measures, and jam enemy radar signals.” The cancellation of the upgrade combined with the increased budgetary constraints faced by the Air Force, particularly in light of Congress’ insistence that the service retain its large but ageing A-10 Warthog attack fleet which has strained expenditures more than expected, has led a number of analysts to speculate that the F-15C/D’s cancellation remains likely. With 192 air superiority variants of the F-15 in service today, they represent the United States’ only high end air superiority platforms other than the F-22 Raptor - the Eagle’s next generation replacement. While the F-22 was initially planned to replace the Eagle entirely, with 750 air superiority variants of the aircraft set to enter service in the Air Force alone, the premature cancellation of the program meant that the service has had to keep its Eagles flying far longer than expected. While the F-15E Strike Eagle, a separate fighter based on the same airframe but allocated an entirely different role, is set to be retained indefinitely, largely as a result of the complete cancellation of the FB-22 strike fighter program which was set to replace it, the F-15C/D air superiority variant could well see retirement far sooner. With the F-15 having entered service in 1978, two years after the F-14 Tomcat which was designed to fulfil a similar role for the U.S. Navy, the platform is increasingly considered obsolete by much of the U.S. Air Force leadership. With the Tomcat having been retired in 2006, despite the lack of any new carrier based air superiority platform to replace it, it was considered only a matter of time before its land based counterpart saw a similar fate. Air Combat Command chief General Mike Hostage for one, when stressing the importance of the F-22 Raptor, predicted that the F-15 would be entirely obsolete as an air superiority fighter by 2024. While the F-15C/D is still among the most capable fighters in the world, able to far outperform all Western made fighters other than the Raptor but including lighter and less specialised&nbsp;F-35 and Eurofighter Typhoon in air to air combat, the aircraft struggles to contend with the near peer air superiority platforms developed since the Eagle’s induction and fielded by a number of the United States’ potential adversaries. The Su-27 Flanker, a fighter developed by the Soviet Union specifically to outperform the F-15 in combat which entered service in 1985, has been extensively modernised since its induction and proliferated widely across four continents. Advanced platforms based on the Su-27 airframe, including the Russian Su-30, 33 and 35 and the Chinese J-11B and J-15 all significantly surpass the Eagle in their combat capabilities, and are today fielded by over fifteen countries - with several hundred deployed by Russia and China each. While the F-15 retains a significant advantage over even the most modern light multirole fighters such as the Russian MiG-35, French Rafale and Chinese J-10 in air to air engagements, its continued viability as an air superiority platform remains highly dubious considering the vastly superior capabilities now widely fielded. This situation is only set to worsen for the U.S. as even more advanced fifth generation air superiority platforms such as the Chinese J-20 enter service in greater numbers, while high end fourth generation aircraft such as the Su-35 and J-11D begin to be used more widely. Should the United States choose to retire the F-15 its already undersized air superiority fleet, less than half the size of China’s today, would be even more vastly outnumbered until a sixth generation replacement for the F-22 itself can be developed. This next generation fighter will likely cost far more than even the Raptor itself however, and is unlikely to be fielded in large enough numbers to compensate for the F-15’s retirement. While Lockheed Martin has proposed designing a new fifth generation air superiority fighter based on the F-22’s airframe, whether this program will go ahead and how the U.S. Air Force will be able to afford it remains to be seen. The United States’ Air Force’s only feasible option to retain a sizeable air superiority fleet appears to be the retention of the F-15, and though the Eagle is far outmatched by more advanced air superiority platforms today a number of solutions to this issue have been proposed. The Boeing company for one has offered to significantly upgrade the F-15 into a ”˜4++ generation’ air superiority platform, carrying out an extensive upgrade and life extension program which would allow the enhanced Eagles, dubbed F-15 2040C, to contend with and likely surpass the capabilities of the Su-35 and other advanced Flanker variants. This would include doubling the fighter’s missile carriage to 16 air to air missiles, modifying the aircraft to carry new AIM-120D air to air missiles with a 180km strike range, and equipping it with fifth generation avionics including state of the art AESA radars, cockpit displays and infra red search and track systems. Whether the Air Force will opt to upgrade its Eagle fleet to the F-15 2040C or some other enhanced variant, allowing it to retain a viable and sizeable air superiority fleet key to retaining parity with near peer adversaries, or whether they will instead opt to retire the F-15 from service leaving the fleet poorly placed to contest air superiority with near peer rivals, remains to be seen.