Let’s Talk About the Air Force Potentially Replacing the F‑15E With the F‑15EX 

 In Air, Forces & Capabilities

It seems like a straightforward idea, but it would be controversial and it points to a bigger role for the F‑15 in the U.S. Air Force of the future.

KC-135 Keeps the Eagles Fueled

U.S. Air Forces Central Command — Public Domain

The U.S. Air Force could expand its current F-15EX procurement plans in order to replace its F-15E Strike Eagles, accord­ing to offi­cial doc­u­men­ta­tion. The ser­vice cur­rent­ly aims to recap­i­tal­ize its aging F-15C/D air supe­ri­or­i­ty fight­ers with the new F‑15EX as a pri­or­i­ty, but it has also left the door open to replac­ing its Strike Eagles with the type. Such an ini­tia­tive would­n’t come with­out con­tro­ver­sy though, espe­cial­ly in terms of threat­en­ing the Air Force’s long-held, but often ques­tioned F‑35A pro­cure­ment number goal of 1,763 air­frames.

The Justification and Approval (J&A) doc­u­ment lays out the USAF’s case for buying the F‑15EX. It says: “The objec­tive of this pro­gram is to rapid­ly devel­op, inte­grate, and field the F‑15EX weapon system to refresh/replace aging F‑15C/D air­craft. A deci­sion to also refresh F‑15E air­craft has not yet been made, but remains an option.”

The report sets out the Air Force’s rea­son­ing for the sole-source con­tract being award­ed to Boeing for F‑15EX, and it was signed off by USAF acqui­si­tion chief Dr. William Roper in August 2019. It care­ful­ly lays out the urgent plans to replace an F‑15C fleet that it is run­ning out of air­frame hours. It adds: “The F‑15 fleet is in dire need of a refresh, in par­tic­u­lar the F‑15C/D fleet, which with­out an expen­sive ser­vice life exten­sion, will run out of air­frame flying hours in [redact­ed}.” In keep­ing with major recap­i­tal­iza­tion projects, the timing would sug­gest that, when it comes, the need to replace the Strike Eagle will be just as urgent as it is cur­rent­ly for the F‑15C/D.

You can check out the doc­u­ment for your­self here:

The first pro­duc­tion-stan­dard F‑15E Strike Eagle made its maiden flight on December 11, 1986, from McDonnell Douglas’ Street Louis, Missouri, plant. The first of 236 pro­duc­tion Strike Eagles was handed over to the 461st Tactical Fighter Training Squadron “Deadly Jesters” on April 12, 1988. The first oper­a­tional unit — the 336th Tactical Fighter Squadron (TFS) “Rocketeers” —start­ed to receive Strike Eagles at Seymour Johnson Air Force Base, North Carolina, in December 1988. The type was famously thrust into combat for Operation Desert Storm in 1991.

National Museum of the United States Air Force

Prior to the first true F-15E's first flight, a TF-15A (F-15B) was used to prove the Strike Eagle concept, acting as a prototype and capabilities demonstrator.


Strike Eagle serial 89 – 0487 from Seymour Johnson became the first exam­ple to reach 12,000 flight hours on August 16, 2016. The F‑15E was beefed-up in com­par­i­son to the F‑15C in order to carry a heavy weapons loads, how­ev­er, like the Eagle, the youngest of which is 35 years old, the Strike Eagles are aging air­frames.

The small 219-strong Strike Eagle fleet remains in high demand with an endur­ing com­mit­ment in the U.S. Central Command region that leverages many impressive niche capabilities. With just six front line Strike Eagle squadrons, at least one is always deployed. The F‑15E is also capa­ble of deliv­er­ing nuclear weapons and is the first jet certified to employ the newest vari­ant of the B61 tac­ti­cal nuclear bomb.

The cur­rent F‑15E fleet fea­tures two dif­fer­ent engine class­es. The oldest jets fea­ture the Pratt & Whitney F100-PW-220E with rough­ly 23,500lbs of thrust. The younger models fea­ture the P100-PW-229 engines with around 29,000lbs of thrust, making them the most capa­ble of the lot by a seri­ous margin. They are also the most numer­ous. The F-15EX is set to receive the F110-GE-129 engine that also has 29,000lbs of thrust.


Buying more F‑15EXs to replace the cur­rent F‑15E would be hugely sig­nif­i­cant. USAF Chief of Staff Gen. David L. Goldfein has made reg­u­lar asser­tions that the F‑15EX will not impact the F‑35 Lightning II pro­gram, but switch­ing later F‑35 pro­cure­ment tar­get­ed at replac­ing the F‑15E to the F‑15EX could impact the over­all F‑35A pro­ject­ed inven­to­ry require­ment. Moreover, the Boeing fight­er has been used as a means to pile com­pet­i­tive pres­sure on Lockheed Martin to reduce F‑35 pro­cure­ment and through-life costs.

The J&A report under­scores the rea­son­ing behind pur­chas­ing the F‑15EX in terms of ease of tran­si­tion: “Refreshing the exist­ing F‑15 fleet (versus tran­si­tion­ing to a new advanced fight­er air­craft) with F‑15EX will dra­mat­i­cal­ly reduce dis­rup­tion to the logis­tics and sus­tain­ment infra­struc­ture, as well as oper­a­tional train­ing and Mission Ready status of cur­rent F‑15 units, by taking advan­tage of inher­ent famil­iar­i­ty with the exist­ing air­craft, which will allow focus on the new and improved sys­tems.”


The case for the urgent replace­ment of the F‑15C/D includes rea­sons regard­ing safety. “The sched­ule impact if there is no refresh is exac­er­bat­ed by the fact that the aver­age age of the F‑15C/D fleet is 35 years. The fleet’s struc­tur­al integri­ty is rapid­ly degrad­ing due to the high‑g flight pro­file used during train­ing and oper­a­tions. One wing com­man­der imposed a G restric­tion due to a loss of con­fi­dence in the safety of the fleet.”

The USAF examined a service life extension for the F‑15C but this was ruled out as not being cost-effec­tive. The speed with which Boeing can build the F‑15EX is cited as anoth­er key dif­fer­en­tia­tor. Based on the for­eign invest­ment in the Saudi Arabian F‑15SA and Qatari F‑15QA projects, the USAF’s F‑15EX will share “90−95 per­cent com­mon­al­i­ty” with the Qatari jets, but it will receive some USAF-spe­cif­ic addi­tions such as Eagle Passive/Active Warning and Survivability System (EPAWSS).


The report adds that buying the F‑15EX “will save the USAF $3 bil­lion over the Future Years Defense Program com­pared to replac­ing that fleet with F‑35s by avoid­ing sig­nif­i­cant tran­si­tion costs required for a new air­craft.” It adds: “The USAF esti­mates that it will take six months or less to tran­si­tion from the F‑15C/D to the F‑15EX given the sig­nif­i­cant com­mon­al­i­ty between the F‑15C/D and F‑15EX air­craft com­po­nents and ground sup­port equip­ment, while the tran­si­tion time from F‑15s to the F‑35 (or any other air­frame) will take approx­i­mate­ly 18 months for an Active Duty squadron and 36 months for an Air National Guard squadron. Accordingly, from both an eco­nom­ic and readi­ness per­spec­tive, no other air­craft will sat­is­fy the USAF require­ment to refresh the F‑15C/D fleet.”

In addi­tion, the doc­u­ment makes it clear that the pre­mi­um once placed on an all stealth tac­ti­cal fight­er fleet has eroded: “The USAF has deter­mined that a mix of 4th gen­er­a­tion capac­i­ty and 5th gen­er­a­tion capa­bil­i­ty is nec­es­sary in bal­anc­ing near and mid-term readi­ness with future needs.”

These were all rea­sons we dis­cussed as per the jus­ti­fi­ca­tion for the ‘F‑15X’ when The War Zone broke the story of its exis­tence two years ago.


There are no offi­cial plans to replace the F‑15E when it is retired from ser­vice, and offi­cial­ly it could remain in ser­vice through life-exten­sion pro­grams. Yet, based on the sit­u­a­tion facing the F‑15C/D, it could be up for replace­ment as early as the end of the decade. Previously, the War Zone was told that the F‑15EX “is intend­ed to direct­ly replace the USAF’s entire F‑15C/D fleet. It would have no impact on the exist­ing F‑15E Strike Eagle fleet or its planned upgrade path­way that is under­way now.”

The F‑15E shares sim­i­lar cut­ting-edge tech­nol­o­gy as is being field­ed in the F‑15EX. It has been upgrad­ed with the Raytheon AN/APG-82(v)1 Active Electronically Scanned Array (AESA) radar, the new Advanced Display Core Processor (ADCP) II, and it too is receiv­ing the new EPAWSS self-pro­tec­tion system.

The cur­rent F‑15EX pro­cure­ment plan as set out ear­li­er this month could be worth up to $22.9 bil­lion over 10 years. This cost ceil­ing is based on a March 2019 F‑15 SPO Rough Order of Magnitude (ROM) esti­mate for the max­i­mum quan­ti­ty of 200 air­craft. However, the report says pro­cure­ment quan­ti­ties will be estab­lished at a Most Probably Quantity (MPQ) of 144 air­craft. Still, this is seen as min­i­mum fleet size, and it is likely to reach near or at the 200 level just in regards to replac­ing the F‑15C/D fully.

The youngest F-15C/D in the USAF's fleet is 35 years old.


The current F-15C/D fleet of approx­i­mate­ly 245 air­craft would be replaced on what would be close to a one-for-one basis if all options are exer­cised. While the report does­n’t dis­cuss actual num­bers, it would sug­gest the sim­i­lar­ly sized F‑15E fleet could be recap­i­tal­ized under a very sim­i­lar model, which would take F‑15EX pro­cure­ment out to rough­ly 400 air­craft.

A USAF spokesman told Air Force Magazine “That deci­sion has not been made,” regard­ing the F‑15E. A common F‑15EX fleet in a merged Eagle com­mu­ni­ty would have its ben­e­fits both logis­ti­cal­ly and oper­a­tional­ly. There is also bound to be some ten­sion between the F‑15C/D units, the vast major­i­ty of which are Air National Guard, and the active-duty F‑15E com­mu­ni­ty under the cur­rent pro­cure­ment plan for the F‑15EX.

As the plan sits, the F‑15EX would equip squadrons whose only mis­sions have been air-to-air combat and air sovereignty with the most advanced and reli­able multi-role F‑15s in the entire force. In other words, the F‑15E com­mu­ni­ty, which is tasked with some of the most com­plex combat oper­a­tions abroad, would be flying aging, par­tial­ly upgrad­ed jets while the Guard has brand new F‑15EX with excess capa­bil­i­ties. This has raised the ques­tion of why does­n’t the F‑15E get replaced with the F‑15EX and the cur­rent F‑15C/D com­mu­ni­ty receive sur­plus F‑15Es?

F-35As and F-15Es in formation.


With over 50 years of pro­duc­tion, the F‑15 is enter­ing into unchart­ed ter­ri­to­ry for fight­er air­craft man­u­fac­tur­ing. Boeing has clev­er­ly retained cred­i­bil­i­ty through rein­vent­ing the F‑15 via foreign investment. With at least 144 new F‑15s enter­ing the Air Force’s fleet in the near term, some 16 years after its last new Eagle was deliv­ered, the prospects for follow-on orders are cer­tain­ly there. This does­n’t mean that recap­i­tal­iz­ing the Strike Eagle fleet with F‑15EX is any­where near a done deal, but the door is open and it might just prove to be anoth­er case of the swiftest, cheap­est, and most sen­si­ble way to keep some of the Air Force’s most impor­tant fight­er squadrons in busi­ness.

Regardless, with the F‑15EX’s stated ser­vice life of a whop­ping 20,000 hours, the Eagle will be grac­ing American fight­er wing ramps well into the second half the cen­tu­ry.

Contact the editor: Tyler@thedrive.com

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