The third and last phase of the United States Air Force tanker fleet modernization is likely to take place earlier than expected. 

Initial studies known as the analysis of alternatives (AOA), which assess the relevance of a program, could happen in 2024, Paul Waugh, Program Executive Officer for the USAF Mobility and Training Aircraft Directorate, told Breaking Defense.  

The beginning of the program, known as KC-Z, was initially due to start at the beginning of the next decade. 

Since the turn of the millennium, the USAF has been attempting to modernize its fleet of aerial refuelers. After several stalled attempts, it was decided in 2007 to renew the fleet in three installments. 

The first phase, called KC-X, was initially won in 2008 by the A330 MRTT, proposed by Airbus partnered with Northrop Grumman. However, the victory of a non-US manufacturer triggered intense political lobbying. Eventually, in 2011, the contract was taken away from Airbus and given to Boeing, which had offered the KC-46 Pegasus. 

The Air Force has ordered 98 of a planned fleet of 179 KC-46 tankers. But Boeing’s aircraft has encountered numerous technical problems since the first delivery on January 10, 2019.  

Boeing's new tanker, the KC-46, has - to put it very mildly - a lot of problems. A lot. How did Boeing end up offering such an aircraft to USAF?


In June 2021, the Air Force Life Cycle Management Center issued a Sources Sought Notice for the second phase of the program called KC-Y. If it is held, the competition should once again see Boeing’s KC-46 face Airbus’ A330 MRTT, this time in a partnership with Lockheed Martin. 

With the KC-Y program, the US Air Force intends to acquire between 140 and 160 new tanker planes in support of the current Boeing KC-46A Pegasus.


Manufacturers were asked to provide “approximately 140-160 Commercial Derivative Tanker Aircraft—at a rate of 12 to 15 per year”. The KC-Y program is meant as a bridge solution between the KC-X and the KC-Z. The first aircraft is set to be received in 2029, right after the delivery of the first batch of 179 Boeing KC-46A tankers. 

Though the requirements for the KC-Z are unconfirmed, it is slated to be a blank sheet design. Early reports and airshow models hinted at an emphasis on stealth. Now, Waugh mentioned that the AOA would help elaborate a “family of systems,” a similar idiom to the “system of systems” coined by most sixth-generation fighter developers. 

While countries are still developing the 5th-generation fighter jets, the most advanced so far, manufacturers around the world are already outlining the future of combat aircraft. Let's take a look at the most promising ones to try and decipher what could be the 6th generation fighter jets.