The Government Accountability Office (GAO) says low availability of unnamed “legacy” aircraft has created hurdles for flight testing of the new AGM-181A Long-Range Standoff (LRSO) nuclear-armed cruise missile. The B-52 is the only platform known to be involved in this effort. The fleet of these bombers is highly in demand, underscored by heavy use in strikes on Iran earlier this year, and has also recently suffered a tragic loss. U.S. Air Force officials have previously highlighted how the relatively small number of B-52s in service and the heavy demands placed on them create challenges when it comes to modernizing the aircraft themselves. GAO, a Congressional watchdog, provided new details about flight testing plans and other aspects of the LRSO program in an annual report published last week. The AGM-181A has been in active development since 2020, when the Air Force chose Raytheon to be the prime contractor. “LRSO reported unfavorable cost and schedule changes over the past year,” GAO reported. “For example, flight testing challenges, largely due to the poor readiness rates of legacy aircraft supporting LRSO testing, resulted in a 4-month delay to its initial capability.” The Air Force is now aiming to reach initial operational capability with the AGM-181 in November 2030.

GAO says that there have been nine LRSO test flights since October 2024. That is when developmental testing of the missile began. Six of those flight tests, along with seven ground test events, occurred last year. In a report dated December 2022, the Pentagon had previously disclosed nine more test flights as part of earlier phases of the program. Whether additional test flights occurred between December 2022 and October 2024 is unclear. “Since our last assessment, program officials realigned the test schedule, leaving less time to complete the 27 remaining test flights before operational testing starts in September 2027,” the report GAO put out last week also notes. “However, they noted that some re-testing can still be accommodated.” As noted, the B-52 is the only aircraft known to be involved in LRSO flight testing, and certainly meets the definition of a “legacy” platform. The last of these bombers rolled off Boeing’s production line in 1962, though the remaining examples have been upgraded repeatedly since then. The sighting last year of a B-52 carrying a pair of AGM-181s, or relevant test articles, on a pylon under its right wing offered the first public glimpse of the missile. Spotters have caught these bombers supporting LRSO tests on several other occasions since then. The Air Force currently has 75 B-52H bombers in service, in total. The entire fleet is never available at any one time for taskings of any kind, due to routine maintenance and other factors. The mission-capable rate for the bombers has been hovering between 50 and 55 percent in recent years. In addition, only one of the bombers is explicitly set aside to support test and evaluation efforts. B-52s from operational units are also used to support research and development and test and evaluation work on a more ad hoc basis. This is on top of the heavy operational demands put on the fleet, both for conventional combat operations and as a key component of the air leg of America’s nuclear deterrent triad. As mentioned, B-52s were heavily utilized just earlier this year for conventional strikes on Iran, adding to these strains.

Last month, the Air Force also lost one of its B-52s in a fatal crash at Edwards Air Force Base in California, which tragically killed all eight individuals onboard at the time. The aircraft in question was headed out on a flight test in support of a critical radar modernization program for the bombers when it went down, as you can read more about here. The radar modernization effort is part of a slew of major upgrades for the B-52 fleet, which also includes all-new engines, improved communication suites, and more. The upgrades are so substantial that the bombers’ designations will change from B-52H to B-52J in the process. They are also in line to see their arsenals grow, including with the addition of the LRSO. The future B-52Js are set to continue serving through at least 2050. Other aspects of the B-52 modernization plan have also been beset by cost growth and delays. Air Force officials have said this has been compounded by the total size of the fleet and operational demands placed on it. “The challenge with B-52 that I think everybody forgets, it’s such a small fleet that has such a tremendous requirement in terms of readiness,” Air Force Gen. Dale White, the service’s Direct Reporting Portfolio Manager for Critical Major Weapon Systems, told TWZ and others at the Air & Space Forces Association’s (AFA) annual Warfare Symposium in February. “You’ve got to have a certain number on the ramp. That’s a requirement.” The question becomes “how do you get these through the depot while at the same time meeting the operational requirements?” Gen. White further explained at that time. “That choreography, I think, is going to be tough.”

It’s worth pointing out here that both the war with Iran and the crash at Edwards came after the cutoff date for GAO’s report, and further impacts on the LRSO flight test schedule would not have been recorded therein. There has also been a broader surge in demand across the U.S. military for flight test assets. This is being driven by the needs of modernization efforts for several aircraft beyond the B-52, including the F-22 Raptor, as well as next-generation developments, like the F-47 sixth-generation fighter. Going back to LRSO, GAO’s latest assessment also highlights other challenges that the program has been facing that are unrelated to flight testing. “Program officials stated that 12 of 14 software releases are delivered, with the final delivery planned for March 2026. According to program officials, nuclear certification of LRSO software continues to be a risk that they expect to fully address by November 2026. As we reported last year, the program risks delays if additional LRSO software development is needed to satisfy this certification requirement,” per the report. “LRSO cybersecurity testing continues with some delays reported during the past year. Program officials stated these delays did not bring about any cost or schedule changes, with the final cybersecurity assessment still planned for September 2027.” “The missile’s technology maturity has advanced since our last assessment, with only two out of the six critical technologies still approaching maturity. They are both expected to be fully mature in fiscal year 2026, about 5 years after development start. DOE [Department of Energy] also identified critical technologies for the warhead, of which 80 percent are considered mature, more than double the percentage reported last year,” the report adds. “However, DOE may not mature all the remaining warhead technologies until the fourth quarter of fiscal year 2026. As we previously reported, both the missile and warhead started development with immature technologies, requiring parallel technology and design maturity efforts. This method falls short of the best practice to start with mature technologies and would have minimized the risks of future cost increases and schedule delays associated with concurrency during system development.”

There is also cost growth, as well as cost discrepancies. “Program costs increased by $347 million after Air Force leadership directed a 1-year extension to LRSO production due to near-term budget constraints,” according to GAO. “As we previously reported, Office of the Secretary of Defense and Air Force officials continue to work together to resolve a $1.9 billion difference between their production cost estimates for future LRSO production,” the report also says. “While a fully updated estimate is not expected until later in 2026, program officials now agree that OSD’s higher cost estimate provides an appropriate basis for the program’s fiscal year 2027 budget request and future year procurement funding needs.” Buoyed in part by the successful flight testing it has conducted to date, GAO says the Air Force remains confident that it can meet its goal of starting low-rate initial production of the LRSO next year. Hitting that milestone will be key to staying on schedule to start fielding the missiles in 2030.