The U.S. Air Force has confirmed that the United States has started physically building the next-generation B-21 Raider aircraft.

The B-21’s capabilities are the subject of intense speculation, and there is little doubt that the upcoming plane will substantially expand the Air Force’s capabilities. However, the Air Force has a logistics problem: once the Raider enters service, the U.S. Air Force will separately be flying four different bomber aircraft, several of which overlap substantially in their intended missions.

Currently, the United States operates the B-1 Lancer, the B-2 Spirit, and the B-52 Stratofortress. Although the B-1 and B-2 are intended to be phased out over time, this process will take at least a decade, and during this time, the Air Force’s operation of four separate bombers is likely to be costly and inefficient.

Air Force Lieutenant General David S. Nahom addressed these concerns at a Mitchell Institute for Aerospace Studies event on July 14. Nahom described the four-plane outlook as “not affordable […] The B-1 and B-2, as phenomenal as they are, we’ve got to get those out of service as the B-21 comes on.” Nahom indicated that the Air Force would focus on a two-bomber fleet, consisting of the B-21 and a substantially upgraded version of the B-52.

The B-52 is one of the oldest and longest-serving planes in the U.S. Air Force. The contract to produce the aircraft was negotiated in 1946, and the first B-52’s maiden flight took place in April 1952. Next year, the aircraft will mark its 70th year in service. Roughly seventy of the planes remain in the service of the U.S. Air Force.

The B-52s currently in service, however, have been substantially upgraded from their 1950s counterparts. Nahom described ongoing upgrades to the plane, including avionics upgrades and “re-engining.” The general expressed concern that these planes would be inoperable during the upgrade phase, potentially weakening the U.S. air fleet.

“We’re going to have a deficit in availability,” Nahom said, “while those airplanes are being modified […] That is my biggest concern on the bomber fleet […] over the next, I’ll call it, five to seven years.”

The Air Force has elsewhere indicated that the B-21’s first flight will take place in 2022. At that time, the first of the B-1 and B-2 bombers are scheduled for disassembly at the Air Force’s “boneyard” in Tuscon, Arizona. The Air Force had earlier indicated that the B-1 would be fully phased out by 2036.

Trevor Filseth is a current and foreign affairs writer for The National Interest.

Image: Flickr