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L3Harris Tanker Glass targets KC-135 fleet past 2050
Simple Flying reports on a proposed digital cockpit overhaul that could keep the Air Force's Eisenhower-era tankers flying into the 2050s.
The Air Force needs to keep its oldest tankers flying. Simple Flying reports a proposal from L3Harris for a comprehensive cockpit upgrade called Tanker Glass that aims to keep the KC-135 Stratotanker fleet mission-ready past 2050. The design would strip out old analog instruments and replace them with digital hardware and LED displays.
The upgrade, according to Simple Flying, uses a Modular Open Systems Approach with government-owned architecture. Commercially available components would let the Air Force buy from multiple vendors, reducing its dependence on single suppliers and helping with the shortage of replacement parts. The company says the same package is already used on the RC-135 and WC-135 variants.
The fleet needs the intervention. The Air Force has been waiting on the Boeing KC-46 Pegasus to replace the KC-135s, but deliveries are lagging. Simple Flying reports that Boeing delivered 14 KC-46s in 2025, aimed for 19 in 2026, but fiscal requests have reduced that to 15 per year and pushed deliveries to October 2029. A planned 75-plane order is frozen until Boeing fixes a problem with the Remote Vision System, which is not expected to be fielded until early 2028.
The delays force the KC-135 to keep flying. A Government Accountability Office report from June 10, covered by Simple Flying, found that the tanker fleet failed to meet its availability and mission-capable targets each fiscal year between 2019 and 2025. Parts shortages and KC-46 delays were the main causes. The KC-135 mission-capable rate for fiscal 2024 was just under 68%, while the KC-46 managed 62%.
The Air Force completed its Block 45 cockpit upgrade in fiscal 2024, which installed digital engine displays and other modern equipment. But that upgrade was intended to support the airframe only into the 2040s, not through the 2050s as now required.
Combat losses have worsened the situation. Simple Flying writes that during Operation Epic Fury, Iranian strikes on Prince Sultan Air Base in Saudi Arabia damaged multiple KC-135s and at least one KC-46, and destroyed others. A KC-135R and its six-person crew were lost in a March midair collision over Iraq. The Air Force has begun pulling retired KC-135Rs from the Boneyard to restore them.
The Next-Generation Air-refueling System, or NGAS, which had been planned for the mid-2030s, is still decades away and received no funding in the fiscal 2027 budget. Instead, the Air Force created a $13 million Advanced Tanker Systems line for software development.
Gen. John D. Lamontagne, Vice Chief of Staff, told the House Armed Services Committee that the Air Force has stopped retiring a KC-135 every time a new KC-46 arrives, instead aiming to grow tanker capacity from 466 to 502 aircraft.
"We're no longer doing that so that we can grow our tanker capacity from 466 to 502," Lamontagne said, as reported by Simple Flying.
The L3Harris upgrade is part of that strategy, serving as a low-cost bridge until a new tanker can be developed.
The KC-135 fleet currently numbers 376, including 325 KC-135Rs and 51 KC-135Ts. The first one flew in August 1956. If the upgrade proceeds, these airframes could keep flying into the 2050s.
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