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A KC-46 is marshaled on the flightline at McConnell AFB, Kan., on Feb. 21, 2019. The Air Force is beginning analysis of the future KC-Z tanker this year, while it is still bringing on the first KC-46s. Air Force photo by A1C Alexi Myrick.

The Air Force is mapping out the unprecedented capabilities it will need in a next-generation tanker, laying out an aggressive timeline for the “KC-Z” while it is only just getting the KC-46 to operational status. It’s not expected at this point that the KC-Z will be stealthy, however.

Air Mobility Command boss Gen. Maryanne Miller said it will take a year to identify the capabilities it wants in the future tanker, a process that is beginning right now. These requirements will be driven by the threat, as laid out in the National Defense Strategy and USAF’s Next Generation Air Dominance future fighter system. “We’ll have a tanker that supports” NGAD, she said, though she said it’s too early to say what exactly what will mean; whether, for example, the future tanker will be autonomous.

“Our priority right now is going to be the KC-Z,” she said.

After figuring out what it must have to accomplish the future tanker mission, AMC will start an analysis of alternatives expected in three and five years, toward fielding an aircraft in the mid-2030s, said Maj. Gen. Mark Camerer, the command’s director of strategic plans, requirements, and programs.

“We’re at the very, very beginning trying to describe what the requirements will be,” Camerer said, adding that since this aircraft will be developed from scratch, it will be a “very large investment for the Air Force” and essential that it be done right.

While the specific requirements aren’t set, Miller said it looks for now as if stealth won’t be a requirement for KC-Z. While the tanker may need to get closer to the fight, no one knows how to keep a tanker stealthy once it deploys its refueling boom, so that feature isn’t likely to be required, she observed. Alternately, AMC is looking at a Navy study suggesting a “mother tanker:” a larger tanker that refuels smaller aircraft, which then go forward to refuel other platforms. However, she also called this prospect unlikely.

The move toward a future tanker is launching even as the Air Force brings on the KC-46 because “We have got to get on this,” Miller said. The “Air Force We Need” study found the biggest shortfall in mobility is in aerial refueling, and the planned number of KC-46s is not enough. “We will have 300 KC-135s in the inventory by the time we field the KC-46,” she said. The buy ends in 2028.

The KC-46 was originally known as the KC-X. There was to be a second competition, called KC-Y, to recapitalize the remaining KC-135s, and that program was to be ready in 2028, to follow closely after KC-X. Some AMC leaders have suggested, however, that the KC-Y competition may be skipped, in order to save the time and money of a new contest and simply expand the purchase of KC-46s to promote fleet commonality. The KC-Z project was originally intended to recapitalize the KC-10 fleet in the late 2030s.

Shortly after Miller made her comments, the Air Force said it will delay the retirement of 28 KC-135s due to delays in bringing into service the KC-46s that were to replace them. The move is meant so “we don’t have this exorbitant dip in capability over time,” US Transportation Command boss Gen. Stephen Lyons told the Senate Armed Services Committee on Wednesday.

Miller said the KC-135s have been “heavily used” and face issues such as corrosion, which is “being mitigated, Miller said.

“It’s one of the issues that comes up with a 60-year-old airframe,” she said, adding that the aircraft are otherwise “in great shape.”

Each tanker goes in for in-depth, depot-level maintenance every three years to get a “really good look at the airplane,” Camerer said. Each aircraft is stripped down to check for corrosion and the engines are overhauled. That way, while “the aircraft is 50 years old, the components inside the airplane aren’t 50 years old,” he said.

In addition to structural integrity, the Active Air Force and Air National Guard are further upgrading their KC-135s to keep them relevant. The Guard jets and a small number in the Active fleet are receiving the Real Time Information in the Cockpit system to improve their situational awareness. While the KC-46 comes with factory-installed systems such as Link 16 to be better able to communicate, the older KC-135s require upgrades to be able to stay relevant in the long term, Camerer said.

“We’re still going to be flying KC-135s for a long time,” he said.