The Republic of Singapore Air Force (RSAF) has acknowledge the critical role of its four Boeing KC-135R tankers, which exited operational service in June.
In its official Pioneer newsletter, Singapore’s defence ministry confirmed that the type has exited service following Singapore’s introduction of the Airbus A330 Multi-Role Tanker Transport (MRTT).
It listed a range of missions the type undertook during two decades of service with the RSAF. In addition to air-to-air refuelling work during coalition missions and exercises, the type saw extensive use in humanitarian support missions.
Notable missions included providing support following the earthquake that struck Christchurch, New Zealand in 2011, and flying home Singaporeans injured in October 2000 aboard Singapore Airlines flight SQ006, a 747-400 that crashed while mistakenly taking off from a Taipei taxiway in bad weather, killing 83.
“This was the KC-135R's first aeromedical evacuation mission,” says the report. “The team modified the aircraft, usually used for refuelling missions, to make it suitable for evacuating the casualties. For example, they suspended equipment like intravenous drips from the cabin roof using a looped line normally used by static-line parachutists.”
In the early 1990s Singapore looked at several options for a boom-equipped tanker. These included second-hand KC-135s offered by the US Air Force, and commercial offers from Airbus, Boeing, Israel Aerospace Industries, and McDonnell Douglas. Ultimately, used USAF KC-135s were seen as the most cost effective solution.
The RSAF had initially hoped to lease USAF aircraft, but there were insufficient CFM International CFM56 aircraft available, resulting in a decision to upgrade stored USAF jets to the KC-135R standard.
The total cost of the purchase was $225 million. The aircraft were sent from desert storage to Wichita where they were re-engined with CFM56-2B turbofans. They also received new wiring, a refurbished airframe, and a glass cockpit.
Cirium fleets data shows that the average age of the four KC-135Rs is 57.1 years. They entered service with the USAF in the early 1960s, and were placed in storage in the early 1990s.
Globally, there are still 420 KC-135s listed as in service, with an average age of 58.1 years. Following the retirement of Singapore’s fleet there are four remaining operators. These are the USAF (396 examples), France (14), Turkey (7), and Chile (3).
The RSAF has four in-service A330 MRTTs, out of total orders for six.