The Royal Saudi Air Force (RSAF) deployed six of its new Boeing F-15SA Advanced Eagles to participate in the latest Red Flag exercise (Red Flag 19-2) at Nellis AFB, Nevada. This afforded the U.S. Air Force its first close-up view of the latest variant of the second-generation F-15 Advanced, since the decision to include the similar F-15EX in the Pentagon’s Fiscal Year 2020 budget request.
The F-15K Slam Eagle for Korea marked the first step on the road to the F-15 Advanced. A derivative of the F-15E Strike Eagle, the F-15K introduced an AAS-42 IRST (infrared search and track) system, an enhanced Tactical Electronics Warfare Suite, and the Joint Helmet Mounted Cueing System, and was fitted with an AN/APG-63(V)1 radar that incorporates digital processing. This made it upgradable to APG-63(V)3 standards via an Active Electronically Scanned Array (AESA) antenna modification. The F-15SG for Singapore was fitted with an AN/APG-63(V)3 AESA radar and a BAE Systems Digital Electronic Warfare System (DEWS), among other enhancements.
The F-15SA for Saudi Arabia was the first variant to formally use the F-15 Advanced/Advanced Eagle name. It introduced a fully digital cockpit and featured a digital fly-by-wire flight control system that permitted the reactivation of two outboard underwing hardpoints, known as Stations 1 and 9, which had been deactivated early in the F-15 program due to stability issues.
In 2010, the RSAF requested 84 new-build F-15SA jets and an upgrade/remanufacturing program to bring 70 (later reduced to 68) existing F-15S aircraft to the same standard. The rebuilt aircraft are sometimes referred to as F-15SRs. The first four F-15SAs ordered by the Royal Saudi Air Force (two new-builds and the first pair of F-15SR conversions) were delivered to King Khalid Air Base at Khamis Mushayt on December 13, 2016. Qatar ordered 36 further improved Advanced Eagles under the designation F-15QA, with large area displays and other improvements.
In early 2017 the U.S. Air Force approached Boeing, inquiring about the acquisition of a similar F-15 variant, dubbed F-15X. The USAF wanted to boost its shrinking force structure and to reinforce its air defense capabilities, but without disrupting the larger F-35 program. The proposed F-15X for the USAF (known as the F-15CX in single-seat form or as the F-15EX in two-seat form) combines the advanced features of the F-15SA and F-15QA with an AN/APG-82 AESA radar—as used by upgraded F-15E Strike Eagles. The new aircraft would offer a 20,000-hour service life as well as a dramatic reduction in hourly operating costs compared to the legacy F-15 or to the F-35A.
Procurement would likely start with eight aircraft that have been requested in the FY20 budget. There is a stated plan for a total of 80 through 2024, with roughly 18 each year from 2021 to 2024. A tranche of 144 aircraft would “initially refresh” squadrons that fly Cold War-era F-15C Eagles designed for air-to-air combat. The USAF might eventually hope to directly replace the USAF's entire 235-strong F-15C/D fleet and could eventually refresh the 218-aircraft F-15E fleet.
The budget request for new F-15s is, however, likely to face political headwinds in Congress, where there is opposition to any procurement that diverts funds that could be potentially spent on more F-35s.