WASHINGTON — A rapidly fielded counter-fire radar was not able to detect and differentiate volley-fired mortars in tests, the Pentagon’s chief weapons tester has found, but the Army says said it has a plan to fix the problem.

While the Q-53 Counterfire Target Acquisition Radar System was found to be effective against single-fired rockets, artillery and mortar munitions during a second initial operational test and evaluation (IOT&E) at Yuma Proving Ground, Arizona, in June 2015, it wasn't able to handle the detection of more than one munition fired at the same time, J. Michael Gilmore, the director, Operational Test & Evaluation, finds in his annual report released Feb. 1.

"Volley-fire is a common technique used by a variety of threat nations and an important component of an operational evaluation for the counterfire radar," Gilmore statesd.

The Army has a contract with Lockheed Martin to rapidly field 38 of the radars in support of an urgent material release, but the service plans to buy a total of 136 radars. First fielded in 2010, the radars will replace the legacy AN/TPQ-36 and AN/TPQ-37 Firefinder radars.

Because of the Q-53 radar’s performance in its first IOT&E, the program office decided to postpone a full-rate production decision to November 2015, the report notesd. The second IOT&E used two radars during five, continuous 72-hour record test scenarios.

"The radar will report false targets when no projectiles are in the search area," Gilmore writes wrote, adding, "a false target occurs when the radar determines that a threat weapon is firing, when none is present."

The radar also struggled to tell the difference between a mortar, a rocket, and artillery. While the radar was able to correctly identify single-fired mortars, it mistook rockets and artillery as mortars, Gilmore notesd.

"Operators are not able to distinguish between real and false targets, which can result in wasted counterfire missions and loss of confidence in the radar," he adds added.

Particularly when operating near an air station, the radar had "high false target rates" likely due to activity there, Gilmore says said. "The program office is investigating ways to reduce the Q-53’s false target rate."

During the second IOT&E, Gilmore found the radar also "incorrectly" calculated the "terrain mask" causing projectile trajectories to fly below the radar beams. This may happen more often in mountainous terrain, he notesd.

Gilmore said the program office is developing a fix for the problem and is testing it.

The test also did not include 240 mm or 122 mm cannon artillery which will be addressed in the full operational test and evaluation (FOT&E).

Despite the shortcomings, the radar was deemed operationally suitable due to its high operational availability of 99 percent, which exceeded the 95 percent requirement.

Yet the radar is not meeting reliability requirements, due to  because of the total number of failures, and it is also not meeting doesn't meet maintainability requirements, according to Gilmore.

The program executive officer for missiles and space approved the program's entrance into Full Rate Production (FRP) on Dec. 22, 2015, and assessed the program as operationally effective, survivable and suitable, Army spokesman Dan O'Boyle told Defense News. The DOT&E "fully supported" the decision, he said.

The Army has developed a strategy to address the DOT&E report through more testing in fiscal year 2019, which includes the development, test and implementation of software upgrades to improve system reliability as well as the implementation of product improvements to enhance system performance in "high-clutter environments and against low-quadrant elevation targets," O'Boyle said.

Additionally, the Army will test the 240 mm and 122 mm munitions not assessed in previous tests.

"The system has performed exceptionally well in real-world contingency operations in both Iraq and Afghanistan," O'Boyle said.

The radar is deployed in support of Operation Inherent Resolve — the military operation against the Islamic State group. The radar's operational readiness has been 100 percent over the past eight months of "continuous" operations, O'Boyle said.

The program is on track to obtain a materiel release in the second quarter of fiscal year 2016 with fielding to the fleet beginning in the third quarter of fiscal year 2016.

Email: jjudson@defensenews.com

Twitter: @JenJudson

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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