As an air refuelling operator previously on the KC-135R aerial tanker, First Sergeant (1SG) Jonathan Paul Augustine was among the second batch of operators to convert to the newly-acquired Multi-Role Tanker Transport (MRTT).

For the Republic of Singapore Air Force (RSAF) airman, the new aircraft is a significant upgrade over the KC-135R, which was acquired second-hand from the United States, and has ceased operations after more than 20 years in service.

For instance, instead of having to lie prone and look through a window in the back of the KC-135R to refuel fighter jets, he now does so sitting in the MRTT cockpit while wearing special glasses that allow him to see a 3D model of the situation at the back of the plane.

The Airbus A330 MRTT, which has replaced the KC-135R, is taking part in its first overseas exercise at Exercise Forging Sabre, held at the Mountain Home Air Force Base in Idaho from Sept 30 to today.

It was the first time air-to-air refuelling was done as part of the integrated strike exercise involving around 600 soldiers from the Singapore Armed Forces (SAF).

Such refuelling allows RSAF fighter jets to take on longer missions in a single flight.

Reporters witnessed one such airborne refuelling mission on board the MRTT on Tuesday, when five fighter aircraft were refuelled in a three-hour flight.

1SG Augustine said that in the KC-135R, manual adjustments might still be needed after the boom refuelling system is connected to maintain the alignment in midair. In the MRTT, such adjustments are done automatically.

However, he said that despite the automation available, an operator's skill still matters, especially during the critical part when the fighter jets move in to connect with the MRTT for fuel.

"While there are visual aids to help us, when you are going in for the contact, it's all on you control-wise. You have full control when you're going for the contact," the 26-year-old airman said.

The RSAF operates four MRTTs, which offer improved endurance, cargo and passenger capacity over the KC-135R.

The MRTT can carry a maximum weight of about 111,000kg, consisting of fuel, cargo and passengers.

The maximum capacity for cargo and passengers is about 45,360kg.

Major Victor Ong, an MRTT pilot, said flying the KC-135R was like wrestling with a beast, and required a lot of hands-on control to fly smoothly.

"The MRTT (control system) is fly-by-wire. It is more automated and smoother because your inputs are more calibrated," said the commanding officer of 112 Squadron, which operates the MRTTs.

In wartime scenarios, as the MRTT is considered a high-value target, it is usually deployed in a safe zone, added Major Ong, 36.

But it is able to fly out with the fighters if the situation calls for it.

He added: "When we do that, there will be high-value unit protection procedures in place."

Fighter jet crews appreciate the increased endurance which allows them to fly longer missions.

Captain Leonard Brandon Lim, an F-15SG pilot, said the transition from being refuelled by the KC-135R to the MRTT was seamless. Citing a mission in which fighter jets had to employ live munitions at the Utah Test and Training Range, the 28-year-old said: "With the support of the MRTT, we're able to get there and employ our munitions, take some gas, and conduct additional profiles for more training in accordance with the exercise's tasking, which includes striking additional targets."