NEWTOWN, Conn. -- The C/KC-135 aircraft is in the final stage of its service life, both in the U.S. and abroad but the relatively slow production rate for the model's successor, the Boeing KC-46 Pegasus, is projected to modestly extend the program's service life. Under the United States' latest FY22 budget plan, the ultimate retirement date for the full C/KC-135 fleet is projected for 2060.

However, the annual rate at which C/KC-135 aircraft ought to be retired in the intervening period remains a matter of considerable debate within both USAF and U.S political circles. Cost-conscious USAF planners have generally favored an expedited divestment schedule for the aircraft, but have faced opposition in the legislature on both economic and readiness grounds. The USAF had requested a planned divestment of 13 aircraft during negotiations for the FY21 budget plan, but legislative opposition to this move saw divestments shifted to the service's KC-10 Extender inventories instead.

In May 2021, the leadership of the U.S Transportation Command (TRANSCOM) indicated that the impending resolution of various long-standing performance issues with the KC-46 program would allow for an accelerated retirement timeline for segments of the C/K-135 fleet. The USAF has requested for 18 C/KC-135 aircraft to be divested for FY22, but these plans remain provisional at the time of writing and FY22's retrofit funding requests account for the service's complete inventory.

The USAF is likely to provide only as much funding as necessary to keep the KC-135s in service until they can be retired without creating a gap in the service's critical airborne refueling capability. An exception may be a future LAIRCM upgrade, which may be necessary to keep pace with rapidly evolving air defense capabilities worldwide, but to date developmental work on this program has near exclusively favored the newer KC-46.

R&M activity focuses primarily on electronics, with a particular emphasis on sensory and communications capabilities. As the aircraft is one that, in a near-peer conflict, would be flying in what may be conflicted air space, maintaining parity with evolving adversarial capabilities is key. Such developments as the Block 45 upgrade, MUOS radio integration, and Aero-I satcom upgrades will extend the viability and survivability of the platform for the forecast period, near the end of which retirements may have started in earnest. For the most part, the funding requests submitted for these programs under the FY22 budget have aligned with prior expectations, suggesting that development and implementation work is progressing relatively smoothly and on schedule.

The United States is not the only country divesting the C/KC-135 series from frontline service, with both France and Singapore having acquired new-build Airbus A330 MRTT aircraft as successors for their aging C/KC-135 series inventories. Singapore is in the early stages of transferring its KC-135R fleet into the private ownership of the refueling and support specialist Meta Aerospace.

As aircraft are retired, some of the unneeded C/KC-135s may be sold or donated to other nations, with or without additional modifications to meet the new operators' specific needs. However, the series' potential as a secondhand export asset will be much circumscribed by the pronounced maintenance costs associated with aircraft of such an advanced age and the rising availability of capable alternatives. Still, Chile has already purchased three of these aircraft, and some existing operators may purchase older airframes for use as a pool for spare parts.

The USAF also maintains a number of C-135s as multipurpose transport and reconnaissance aircraft. The RC-135 Cobra Ball, Rivet Joint, Combat Sent, and Constant Phoenix programs feature a variety of enhancements and updates intended to improve integration between the RC-135S, RC-135V/W, and RC-135U fleets, and to match competing enemy capabilities.

Beyond the 2050s, as major operators acquire larget quantities of newer aircraft to fulfill their aerial tanker needs, the size of the global fleet of C-135s will fall dramatically, accompanied by an increasing focus on the surveillance variants. In time, even the RC-135 will be overshadowed by more modern alternatives.

Source: Forecast International