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​The Air Force cannot afford to increase the size of its bomber enterprise, so as the new B-21 bomber comes online, it must divest some of the legacy bombers. Here, all three of the Air Force's current variants conduct a flyover at Barksdale AFB, La., Feb. 2, 2017. USAF photo courtesy of Sagar Pathak.

With the Fiscal 2019 budget request, the Air Force is beginning an overhaul of its bomber fleet, planning to extend the B-52 beyond 90 years of service while retiring its younger B-1s and B-2s earlier than planned, in the early 2030s, as it brings on stealthy new B-21 aircraft. The Air Force is eyeing a bomber fleet of roughly 175 aircraft overall, although service officials said that number could go up with more generous budgets. 

The younger bombers would be retired early because the Air Force believes it must live with a bomber enterprise manpower footprint that is not much larger than it is now, meaning the new B-21 must replace—and not be additive to—much of the existing bomber fleet.

The Air Force had previously planned to operate the B-1 and B-52 until 2040, and the B-2 to 2058.

In judging which older bombers to retain, USAF chose the B-52 over its younger stablemates because of the aircraft’s versatile conventional payload, comparatively lower maintenance needs and the ability to carry the new Long Range Standoff cruise missile, or LRSO. The B-1, meanwhile, is labor-intensive and treaty-prohibited from carrying cruise missiles, and the B-2 fleet, at only 20 aircraft, is considered too expensive per airplane to retain beyond the early 2030s.

The Fiscal 2019 budget request will include the first monies necessary to begin equipping the B-52 fleet with new engines that will reduce its maintenance needs, extend its range and loiter time, and allow the aircraft to climb faster to cruising altitude. It would be retained into the 2050s.

The Air Force envisions retaining all existing bomber bases, swapping out B-1 and B-2 aircraft as B-21s become available. Very substantial military construction funds will be needed to accommodate the new aircraft, however.

The revelations were contained in USAF’s “Bomber Vector,” (previously called the “Bomber Roadmap”) which has been in development for several years and plans the phase-in of the B-21, the phase-out of older aircraft, and the timing and scope of upgrades and new munitions needed for the bomber enterprise. A draft of the Bomber Vector was obtained by Air Force Magazine. The Air Force plans to release a synopsis of the Vector along with its FY ’19 budget request supporting materials on Monday.

The Bomber Vector was to have been released last September at AFA’s Air, Space & Cyber Conference. It had been briefed to members of Congress by Global Strike Command chief Gen. Robin Rand during the summer months, and Chief of Staff Gen. David Goldfein announced at an AFA event in July that it would soon be released publicly. However, service leaders decided to wait to withhold it until after release of the Nuclear Posture Review and final decisions on the Fiscal ’19 budget request.

The NPR was released in early February, validating the need for the LRSO and retaining the B-52 as its launch platform for the near future. The B-21 will also be able to carry the LRSO, and the NPR said the missile will ensure the US continues to have a means to strike any target on the globe even after adversary technological advances whittle down the B-21’s stealthiness in the decades to come.


The Air Force plans to retire the B-2, shown here at Andersen AFB, Guam, more than a decade earlier than expected to make room for the new B-21 stealth bomber. Air Force photo by A1C Gerald Willis​.

The draft version of the Vector said the B-2 would be retired “no later than 2032” and the B-1 “no later than 2036,” although service officials said those dates may have shifted somewhat.

“Included in the decision calculus to retire the B-1 and the B-2,” the service said in the draft, is the need to try to maintain a “force-neutral manning structure,” and to do it, it must “harvest manpower billets from the retiring platforms.” Even so, the service sees growth in the bomber fleet from 157 aircraft today to at least 175, in order to provide the capability required by regional commanders, and so “some manpower growth is inevitable."

Keeping all existing fleets and adding the B-21 to them—for a total of 257 aircraft—“is neither fiscally realistic nor desirable,” USAF said in the Vector draft, adding that Global Strike Command “must pursue the optimal bomber force mix.” Simply shaving down the numbers of each type isn’t effective, the paper said, since it would require keeping all four logistical trains in place, each with their separate people, parts, and vendors. The bomber force today numbers 10,500 operations and maintenance manpower authorizations.

“Enterprise-wide reallocation of money, facilities, and other resources are necessary to facilitate B-21 fielding and ensure the Air Force has a capable and effective future bomber force,” USAF said in the paper. It pegged the cost of modernizing the B-1 and B-2 to keep them capable to 2050 at $38.5 billion, “which is enough money to fund modernization upgrades for the B-52 and help fund bomber base modernization and nuclear infrastructure.”

Upgrading the B-52 to last until 2050 would cost $22 billion, USAF said, but “this figure is offset by $10 billion cost savings from re-engining, which pays for itself in fuel, depot and maintenance costs, and maintenance manpower in the 2040s.”

After the B-1 and B-2 retirements, the Air Force would field a fleet of at least 100 B-21s and 75 B-52s.The timing also suggests B-21 deliveries will average less than one a month during production. The Air Force has said it plans to have a “usable” asset when the first aircraft is delivered in the “mid-2020s.” Assuming that production of the new bomber continues until the last B-1B is retired, a production window of 2025-2036 is likely. Dividing 100 bombers over 11 years suggests a rate of about nine aircraft annually. 

Former Air Force officials have hinted at such low numbers, explaining that the service wasted a lot of money tooling up to produce B-2 bombers at a high rate and then built only 21 airplanes, instead of the planned 132. At less than one B-21 a month, large savings can be reaped in facilitization, manpower, and tooling, although there would likely be offset costs in learning curve and economic quantity materials purchases.

The Air Force plans to re-engine the B-52 Stratofortress and conduct other upgrades that will keep it flying nearly a century after it was first introduced to the fleet.​ USAF photo by TSgt. Joshua J. Garcia​.​

Under the Air Force’s proposal, the 1963-vintage B-52s will receive a number of upgrades and improvements to keep them relevant in a world where they are too radar-reflective to get close to well-defended enemy airspace. With new engines, the B-52s would never have to stand down for engine overhauls, as the time “on wing” of the new powerplants would exceed the planned remaining service for the old bombers.

The B-52s would also be equipped with new standoff weapons allowing them to shoot into enemy territory from well outside the range of enemy air defenses. Among these would be the LRSO, which the Vector identified as the AGM-180/181, a possible reference to the two competing versions being developed by Lockheed Martin and Raytheon.

Goldfein, at the July event, said the new bomber force would be paired with intelligence, surveillance, and reconnaissance assets such as the RQ-4 Global Hawk to shoot targets at long range, yet with high accuracy.

The Bomber Vector draft made no mention of hypersonic missiles or any other wonder weapons that could enhance the B-52’s lethality, although it did say the venerable aircraft would be perfectly fine in operations where enemy air defenses either did not exist or had already been beaten down by other systems.  

The Air Force said the decision to retire the B-1 and B-2 instead of the much-older B-52 was based largely on the maintenance track records of the three aircraft. The B-1s and B-2s have higher non-mission-capable rates than the B-52, driven in large part by “vanishing vendor syndrome” situations where components—especially electronics—are no longer made. In the case of the B-2, the fleet is so small—only 20 airplanes—that vendors don’t want to tool up to provide parts in such low quantities. Other pieces of key gear, such as gyroscopes on the B-2, for example, “are obsolete,” the Vector reported, and maintainers are already making do by cannibalizing parts.

The B-1’s maintenance man hours per flying hour (MMH/FH) are the worst of the lot, at 74, while the B-2’s performance in this metric is 45, but that doesn’t count the hours needed to maintain its low-observable features, coatings, and materials, which the Vector did not state. The B-52’s MMH/FH rating was 62.

The Air Force said the B-52’s mission capable and aircraft availability rates consistently outperform those of the newer bombers. The B-52’s aircraft availability has averaged nearly 80 percent over the last five years, while the B-1 and B-2 averaged about 50 percent. In mission capable rates—meaning the aircraft is able to exploit its full range of capabilities, without any non-working systems—the B-52 averaged about 60 percent, while the B-1 averaged around 40 percent and the B-2 about 35 percent.

Cost per flying hour was another factor weighing against the younger bombers in USAF’s thinking. Both the B-1 and B-52 averaged about $70,000 per flying hour (USAF did not call out specific numbers and its charts were not fine-grained)—while the B-2 costs between $110,000 and $150,000 per flying hour to operate. Total ownership costs followed similar curves.

As advanced air defenses proliferate, for the time being, only the B-2 can penetrate them to hold targets at risk worldwide, USAF said. However, that aircraft will “see its technological advantages diminish in the not-too-distant future.” By contrast, the B-21 has been “designed to operate in this highly contested combat environment.” The B-52, despite not having the ability to penetrate, offers a lot of capability through “its high weapons carriage capacity and vast munitions diversity” to be of value either as a standoff platform or in “less challenging environments.” The LRSO will provide “a highly survivable, standoff nuclear weapon capability for the B-52 and B-21.” Some money can be saved by not fitting the B-2 with the LRSO, as had been planned.

The Bomber Vector pointed out that USAF’s bomber fleet has never been so small. Today’s fleet of 157 bombers (76 of which are B-52s) is only a tiny fraction of the 1960 bomber fleet of 1,526 aircraft. The Air Force said its bomber fleet is also spoken for many times over, on tap to support many missions all at the same time.

“In the last five years, [Air Force Global Strike Command] has gone from supporting one enduring COCOM [Combatant Commander] requirement to an average of 12 annually, a 1,100-percent increase. To meet this level of demand, AFGSC’s operation and maintenance personnel and bomber airframes are managed at peak utilization rates,” USAF said. These add-on missions include nonstop bomber action in the Middle East against ISIS targets and an increasing tempo of bomber deployments to the Pacific, both as a messaging device to China and North Korea and to conduct the now-routine Continuous Bomber Presence mission, out of Guam.

The Vector says that USAF’s preference is that “bombers replace bombers” at existing locations, since these bases are operationally and geographically “best suited” to the mission. Opening up new facilities or re-activating dormant ones would add a big cost penalty to build new weapons storage facilities, the service said. Even so, the price tag will be “several hundred million dollars per base” to properly modernize and add new “classified workspaces” at current bomber bases to protect B-21 technology, and to accommodate new weapons.

To help manage the manpower transition among the four systems, the Vector recommended a “hybrid ​manpower approach,” while fielding the B-21, using personnel “from retiring platforms as well as a Total Force and Contractor Logistics Support approach as necessary to minimize manpower spikes and delays” to implementation of the Bomber Vector.​