In the early hours of February 11 it was announced that the Indonesian Defence Ministry had signed a $13.9 billion contract for the acquisition of 36 Boeing F-15 Eagle heavyweight fighter jets from the United States. This made Indonesia the seventh client for the fighter after Israel, Japan, Saudi Arabia, South Korea, Singapore and Qatar, with the heavyweight fighters having seen relatively few exports primarily due to their high operational costs and maintenance requirements. Indonesia has since the 1990s operated heavyweight and lightweight fighters in parallel, and currently deploys a fleet of heavy Russian Su-27 and Su-30 jets complemented by lighter American F-16s. While Russian fighters were initially expected to be replaced by more modern Su-35S ‘4++ generation’ fighters, American threats to impose economic sanctions on the Southeast Asian country should acquire high-performance Russian weaponry led Jakarta to alter its plans and purchase F-15s in their place.
Although the designation of Indonesia’s F-15s remains uncertain, they are expected to be closely based on the F-15EX currently on order for the U.S. Air Force. The Su-35 and F-15EX are both based on rival Cold War era designs, the former the Su-27 Flanker and the latter the F-15C Eagle, which were the prime fighters of the Soviet and U.S. fleets during the period. Although the Flanker was considered the more capable fighter during the Cold War, as demonstrated in multiple exercises and simulations and attested to by multiple American military officials such as Air Force Chief of Staff Michael Ryan, the collapse of the Soviet Union and sharp contraction of the Russian tech sector allowed the U.S. military aviation industry to largely bridge the gap. The F-15EX is thus considered to stand a better chance against the Su-35 than F-15s from the 1980s did against the Su-27. The latest F-15 variants benefit from avionics, data links and sensors which are considered at least on par with if not more capable than those of the Su-35. The Russian fighter by contrast has significantly more powerful engines, three dimensional thrust vectoring capabilities for improved manoeuvrability, and an extended 400km air to air engagement range using R-37M missiles where F-15s can only fire an estimated 160-180km using the R-37M. The Su-35 also benefits from use of triple radars, with two L-band AESA radars embedded in its wings, where the F-15 uses only a single AESA radar in its nose. This provides the Russian fighter with unique electronic warfare capabilities and likely a superior performance against stealth targets.
An important advantage of the Su-35 program is that the Flanker family of aircraft to which it belongs has been at the core of Russian tactical combat aviation since the Soviet collapse, with the large majority of new fighters acquired since the Soviet collapse being derivatives of the Su-27, where the U.S. by contrast ceased F-15 acquisitions for almost 20 years from 2001 producing them only for export. More importance has thus been attached to bringing the Su-35 up to a performance standard where it can contend with the latest fifth generation fighters, in part due to Russia’s lack of its own fifth generation aircraft, where the U.S.’ fifth generation programs have made F-15 modernisation less of a priority. While the latest F-15 variants are well matched against the Su-35, the Russian fighter is expected to have an edge with advantages in more key areas of performance particularly for air to air and anti shipping missions.
For the Indonesian Air Force the choice between the Su-35 and F-15 would be a close one if they were offered under similar terms, with the American Eagle potentially advantaged by its greater interoperability with other Western fighters such as F-16s while the Su-35 will be able to use much of the maintenance infrastructure and armaments from the Su-27 and Su-30 and will require significantly less conversion training. The price difference between the two fighters has been tremendous, however, with the F-15 offered for $386 million each while the Su-35, if acquired in similar numbers, would be expected to cost around $78 million depending on the options added. This places the F-15’s cost at 495 percent that of the Su-35, or almost five times the price. In place of 36 F-15s, therefore, Indonesia could have purchased by far the largest Su-35 fleet in the world at 180 airframes – more than all Su-35s ever produced.
This comparison discounts operational costs, however, as both aircraft cost similar amounts to operate meaning sustaining such a large fleet of either fighter would be unsustainable. Neverthless, a comparison of the two fighters’ acquisition costs provides an important example of how much more cost effectively Russia has been able to offer heavyweight fighters for export, as well as the power the United States wields with threats of economic sanctions to effectively press Indonesia to abandon Su-35s in favour of a largely equivalent fighter for five times the price. This is despite the U.S. also placing strict restrictions on how its fighters can be used, including which bases can host them, where Russia has allowed its fighters to be used with almost no restrictions.