Sentinel ICBM faces year delay, Air Force One and F-15EX also at risk: GAO

US Air Force artist’s rendering of the Sentinel in flight. (Credit: US Air Force)

UPDATED 6/21/23 at 8:05 AM CET with clarification on the KC-46A’s remote vision system timeline from the Air Force, following comment from Boeing.

WASHINGTON — The Air Force’s $96 billion Sentinel program that will field a new fleet of nuclear-tipped intercontinental ballistic missiles is staring down a delay of about a year, the Government Accountability Office warned in a new report today.

GAO’s annual review of Pentagon weapon systems [PDF] also raised concerns about other key Air Force programs, such as the F-15EX, KC-46A and Air Force One replacement known as the VC-25B.

Top officials have signaled in recent months that the Sentinel could fall behind, pointing to issues such as supply chain constraints and workforce disruption. A timeline graphic compiled by GAO now states the missile’s initial operational capability (IOC) date is estimated for between April and June 2030, a delay of approximately one year.

“Sentinel is behind schedule due to staffing shortfalls, delays with clearance processing, and classified information technology infrastructure challenges. Additionally, the program is experiencing supply chain disruptions, leading to further schedule delays,” the watchdog wrote in its report.

“According to the program office, Sentinel’s master schedule contains many deficiencies and cannot be used to effectively manage the execution of the program. The prime contractor and the program are conducting a high-level review and discussing potential changes to the schedule,” the report adds.

The delay would still be within the program’s threshold date of June 2030 to meet IOC, according to a Selected Acquisition Report (SAR) on the program [PDF] released in September, though little (if any) schedule margin appears to remain. The program previously set an objective to meet IOC in June 2029, with an estimate that it could be reached by May of the same year, the SAR says.

A spokesperson for Northrop Grumman, the Sentinel’s prime contractor, did not immediately respond to a request for comment.

Air Force One, F-15EX and KC-46A

The Sentinel is not alone in facing delays. Following a re-baselined schedule set by the Pentagon last year, the VC-25B program is now over two years behind schedule, which GAO found carries continued risk.

Though officials have made progress in some areas — such as prime contractor Boeing ramping up hiring to address labor attrition — the watchdog reports that current test plans “will likely not” finish before a first flight set for April 2024. “If testing takes longer than expected,” GAO stated, “the program may experience
additional delays to future milestones.”

Boeing referred questions on the program’s schedule to the Air Force and confirmed that repairs for stress-corrosion cracks on some of the aircraft’s support structures, which GAO stated are scheduled to be completed this summer, are ongoing. (GAO’s report found the cracking issue did not pose a safety hazard “as long as planned inspections are conducted during scheduled VC-25B maintenance periods.”)

Similarly, the F-15EX program delayed delivery of jets in the aircraft’s lot 1B by six months due to production issues, according to GAO. Boeing plans to deliver the final lot 1B aircraft this year, but citing variance in schedule estimates offered by Boeing and the Defense Contract Management Agency, GAO stated that further aircraft delivery delays could disrupt the IOC and full-rate production decision dates respectively set for July and October 2023. (Boeing referred questions about the program’s schedule to the Air Force. Breaking Defense had asked the service about the IOC schedule on May 25, but did not receive a response by the requested deadline.)

The schedule for Boeing’s long-troubled KC-46A tanker, which recently topped $7 billion in charges, continues to see delays. Last year, officials disclosed that release of a new vision system for the aircraft’s boom operations was pushed to October 2025, and following publication of this article, an Air Force spokesperson confirmed that date has remained the same. The program’s initial operational test and evaluation (IOT&E) phase is currently set to conclude in December 2025, the spokesperson said, following reporting requirements to wrap up IOT&E.

The program has still not set a revised full-rate production decision date, according to the report, which is already seven years behind schedule. Additionally, the KC-46A’s required assets available date — consisting of “18 aircraft in final production configuration with two spare engines and nine wing aerial refueling pods” — was delayed by an extra 21 months to December 2023 since GAO’s last assessment.

That delay was due to pandemic and certification challenges for the pods, program officials told GAO, who added that issues with the vision system “were not directly related” to the shifting of the required assets available date.

The KC-46A’s effort to correct a boom stiffness issue — which Air Force Times previously reported would stretch into 2025 — will now cost slightly more, GAO found, creeping up to $128 million from $113 million “due to subcontractor difficulties meeting design specifications.” The cost to retrofit aircraft for the boom stiffness issue remains stable, however, at about $219 million.