Weapon Systems

In service for decades, KC-135 Stratotankers embody strategic refueling versatility


The large inventory of KC-135s enables the US Air Force to extend the range and endurance of US and allied fighters and bombers anywhere in the world.

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A KC-135 Stratotanker performs a no-contact aerial refueling demonstration with an F-16 Fighting Falcon aircraft during the Sun 'n' Fun airshow last March 29 in Lakeland, Florida. [US Air Force]
A KC-135 Stratotanker performs a no-contact aerial refueling demonstration with an F-16 Fighting Falcon aircraft during the Sun 'n' Fun airshow last March 29 in Lakeland, Florida. [US Air Force]

The KC-135 Stratotanker's aerial refueling capabilities enable it to support the US Air Force's Agile Combat Employment (ACE) concept.

The Stratotanker has extended the range and endurance of US tactical fighters and bombers for more than 60 years.

It can pump 90,700kg of fuel through a flying boom, which is controlled by a crew member during in-flight refueling, according to the Air Force.

Some Stratotanker aircraft have also been configured with the Multi-point Refueling Systems (MPRS) comprising special pods mounted on the wingtips.

The MPRS modification adds refueling pods to the KC-135's wings to allow refueling of US Navy, US Marine Corps and most NATO tactical jet aircraft via the probe and drogue method while also keeping the tail-mounted refueling boom.

These KC-135s are capable of refueling two receiver aircraft at the same time, which directly enables the ACE concept by expanding the type and number of supported aircraft.

Introduced as US Air Force doctrine in 2022, ACE focuses on spreading out power and operations from large, centralized bases to smaller, dispersed locations, providing the force with greater mobility and the ability to rapidly respond to a wide variety of threats.

Physical dispersal further complicates adversaries' abilities to target US Air Force and allied air power, enabling ACE to "increase survivability while generating combat power," according to the Air Force.

The ACE concept centers around multiple, small-scale ground operations in a forward battlefield area supported by multiple fighter and land attack aircraft.

Key to the concept is the KC-135 Stratotanker and its ability to aerially refuel aircraft to get them to their dispersed locations.

Versatility for ACE

The KC-135's flight capabilities also enable it to conduct refueling missions across a wide battle space and in various conditions in support of ACE.

Four turbofans power the KC-135 for takeoff, carrying gross weights topping 146,200kg and enabling it to reach a ceiling of 15,240 meters.

The Stratotanker can also reach speeds of up to 853 km/h at 9,144 meters.

At the same time, the US Air Force's large inventory of KC-135s means that they are readily available anywhere around the world for ACE operations.

The US Air Force maintains 377 KC-135 aircraft, according to Flight Global's 2024 World Air Forces directory. Many fly with the Air Force Reserve and Air National Guard, which operate Stratotankers in support of Air Mobility Command's mission.

The KC-135 Stratotanker also provides aerial refueling support to Navy, Marine Corps and allied nation aircraft.

Such large numbers also mean the KC-135 has a large number of well-trained maintainers as well as a robust inventory of spare parts, making it a reliable mainstay for ACE.

With the model having been in service for more than six decades, each KC-135 Stratotanker undergoes a thorough inspection roughly every two years to preserve its integrity. The Air Force plans to retain the fleet 10 years beyond its planned service life, keeping some jets in service to at least 2050.

The planes have been retrofitted several times with new engines, avionics and structural upgrades.

The life-cycle upgrades have expanded capabilities and improve reliability for the workhorse aircraft. The upgrades include improved communications, navigation, autopilot and surveillance equipment to meet future civil air traffic control needs.

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