WASHINGTON — There were foggy and subtle signs the U.S. Army's key future anti-missile command-and-control system's schedule was slipping, but the service's fiscal 2018 budget request is now showing the initial operational capability, or IOC, of the program is delayed by four years.

And the research, development, test and evaluation, or RDT&E, account in FY18 show an increase of more than half a billion dollars from FY17 through FY21 compared to the FY17 request.

Last year's budget request documents had the IOC milestone set for its Integrated Air and Missile Defense Battle Command System, or IBCS, in the third quarter of FY18, but the new documents released Tuesday show an IOC now scheduled for the third quarter of FY22.

The Northrop Grumman-manufactured IBCS is a key component of the Army's future Integrated Air and Missile Defense System that will replace the Patriot system. IBCS will also connect to other major systems on the battlefield such as the Army's Indirect Fire Protection Capability, or IFPC, system to defend against rockets, artillery and mortars.

"The additional funding and schedule allows for integration with the latest version of Patriot software that is currently undergoing operational test and evaluation; increased time for development, testing and analysis to demonstrate software capabilities; purchase  and refinement, if needed, using RDT&E funds that support the emplacement time for the IFPC as well as addressing potential obsolescence and hardware performance actions; additional cyber and Electronic Attack events as well as additional training time prior to [Limited User Test]," Army spokesman Dan O'Boyle said in a statement sent to Defense News on Thursday.

Bringing IBCS to life is no easy endeavor by nature. It involves complicated software development, and the plans for IBCS on the battlefield have expanded, resulting in the need for more development.

IBCS has completed three successful test flights with four successful intercepts to date.

The Army indicated to Defense News in February that IOC wouldn't happen as planned due to "IBCS software deficiencies" that needed to be resolved, but the service was unable to say how delayed the program was.

While the Army’s budget request this year shows a four-year delay, an April 13 Federal Business Opportunities request for information required before soliciting a noncompetitive acquisition for IBCS shows the possibility of an IOC schedule slip even further than FY22.

"The requirement of this acquisition is to add additional period of performance to the current IBCS development contract," it reads, "for IBCS EMD, [or engineering and manufacturing development], development efforts through 3rd [quarter of] FY21."

Comparison of the FY17 and FY18 requests show a delayed and extended EMD developmental test phase. According to the FY17 document, EMD was supposed to end in the first quarter of FY16 and take five quarters. In the FY18 document, the EMD developmental test phase will take four years. And an "EMD continuation" that started in FY16 will wrap up five years later at the end of FY20.

However, if EMD extends all the way to 2021, as the RFI indicates, the IOC date could slip even further as well.

With major milestone schedule slips, other events in the program have been pushed back.

A Milestone C decision, which would decide whether the program enters a production and deployment phase, was planned for the end of FY16, according to the FY17 budget request, but is now expected at the end of FY20.

And an initial operational test and evaluation scheduled to take place over three quarters in FY18, wrapping up at the end of the third quarter, is now going to start in the fourth quarter of FY20 and won’t finish until the second quarter of FY22, essentially doubling the length of the test period and delaying its conclusion by four years.

Completely missing from the FY18 request are plans for a second limited-user test said to be in the works. The Army has said the second LUT needs to happen before a Milestone C decision.

The service has restructured the program to allow an additional LUT in FY20 "to ensure requirements are met before entering Low Rate Initial Production," O'Boyle said.

The Army has taken delivery of two IBCS software builds that demonstrated marked improvement over the software used in the first LUT, he added.

This year, Army troops will test the updated software at an event at Fort Bliss, Texas, scheduled to complete in September 2017 with further evaluation at a joint interoperability test schedule for Yuma Proving Ground, Arizona, in October 2017. The FY17 document shows a low-rate production test was scheduled in 2017, but the test is missing from the FY18 request.

Also missing in the FY18 request are plans for setting up a First Unit Equipped, which was expected in 2017, according to the FY17 request. A First Unit Equipped is the first unit to be equipped with a capability in advance of initial capability.

In FY18, the Army plans to spend roughly $546.6 million dollars more than it budgeted from FY17 through FY21 in the development and test phase of the program compared to the FY17 request.

And while RDT&E funding received a major increase, the FY18 procurement account shows no money in 2018 or 2019. The Army had originally planned a year ago to spend $287.2 million in FY18 and $372.9 million in FY19 for procurement. The total amount cut from the procurement budget from FY18 through FY21 comes to about $790.536 million.

The IBCS program's delays do not impact currently fielded systems, IFPC or the Lower Tier Air and Missile Defense Sensor program, O'Boyle said. The LTAMDS is looking to replace or upgrade the Patriot system's current radar.

The IBCS delay doesn’t just affect the U.S. Army’s future plans for missile defense. Poland has said it wants to buy Patriot systems with IBCS, and the country has indicated it wants those systems soon as Russia continues to pose a threat to the region.

Poland wants to finalize a contract by November this year to buy eight Patriot systems, and it wants the first two systems with IBCS by 2019.

A waiver is said to have been granted for Poland to procure IBCS at the same time the U.S. Army begins to field it, rather than wait for the U.S. Army to reach a full-rate production capability before selling the system abroad.

When asked whether the IBCS delay could affect its pending deal with Poland, Raytheon said it "can help Poland meet its 24 month timeline for having an operational air defense system, and we stand ready to deliver to Poland a Patriot system with a C2 that is IBCS-ready when IBCS comes online."

Jen Judson is an award-winning journalist covering land warfare for Defense News. She has also worked for Politico and Inside Defense. She holds a Master of Science degree in journalism from Boston University and a Bachelor of Arts degree from Kenyon College.

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