A soldier checks his radio headset in Iraq in 2009. Photo: Army

In key moments during the U.S. Army’s latest war game for advanced communications gear, the troops’ high-tech new radios failed them.

The setting was the semi-annual Network Integration Exercise in New Mexico in May and June. The radio in question: the General Dynamics Manpack, a backpack-portable version of the Pentagon’s ambitious Joint Tactical Radio System. Voice traffic from the Manpacks was “garbled” and “unintelligible,” according to Michael Gilmore, the Pentagon’s chief weapons tester. In a memo dated July 20, Gilmore declared the Manpack “not operationally effective.” In other words, it didn’t work in mock combat — and it probably won’t work in real combat, either.

But the scathing review hasn’t stopped the Army from doubling down on the meager remnants of the once-mighty JTRS initiative, which aimed to equip the entire U.S. military with hundreds of thousands of cheap, high-tech radios whose smart processors would switch waveforms in an instant, making them the radio equivalent of Star Trek‘s universal translator. Just over a week ago the Army dropped $54 million on 13,000 copies of General Dynamics’ similar Rifleman radio, banking on engineers to work out any bugs like those identified in the Manpack in New Mexico.

Congressional appropriators, however, are skeptical — and it’s their objections that could lead to the Manpack’s demise. That would be only the latest blow to the $17 billion JTRS program, which has seen its various components steadily stripped away over the past several years owing to technical flaws, shrinking it from a Pentagon-wide communications makeover to a modest effort confined mostly to the Army.

The Manpack’s glitch occurred at the worst possible moment for the 1st Armored Division soldiers assigned to use the new radio in simulated battle during the May-June Network Integration Exercise at Ft. Bliss and the adjacent White Sands Missile Range near El Paso. “The company commander was not able to communicate with supporting assets such as fire support and Apache helicopters,” Gilmore wrote.

In addition to voices sounding unintelligible, the Manpack radios at the exercise worked out to a range  of only 7 kilometers, roughly a third as far as old-fashioned radios. The Manpacks were also heavier than advertised: 19 pounds instead of 15.

To be fair, the Manpacks malfunctioned only when running the SINCGARS waveform, designed for transmitting voice and data between scattered combat units. When using the Soldier Radio Waveform, meant for connecting individual troops within a unit, the Manpack radios’ performance “was good,” Gilmore conceded.

Moreover, General Dynamics was able to fix “some” of the Manpacks’ flaws at the network exercise and the rest afterward, according to Defense News‘ Paul McLeary. But that didn’t stop Senate appropriators this month from cutting $190 million from the Army’s $290 million request for Manpacks in 2013. The Army was hoping to buy 4,500 of the radios.

The Senate urged the Army to “leverage commercially available technology” to fill in for the cut Manpacks, something the ground combat branch has done repeatedly over the 15 years of JTRS development. Two brigades slated to go to Afghanistan this fall were supposed to take Manpacks, but program delays that occurred before the Ft. Bliss exercise forced the Army to instead equip the brigades with upgraded, JTRS-compatible PRC-117G radios made by Harris Corporation.

And that’s how JTRS has been slowly rendered irrelevant. Every time there’s been a delay or technical glitch with the next-gen radios, the Army has bought upgraded versions of existing radios: more than 300,000 in all. For its part, Harris has managed to add many of JTRS’ features to the PRC-117G. “We continue to invest in its capabilities, to include porting of other JTRS waveforms,” Dennis Moran, a Harris vice president, tells Danger Room.

The Manpack’s gradual death-by-irrelevance leaves the Rifleman radio, plus niche air-, sea- and space-based radios, as the aspects of JTRS with the best chances of long-term survival. But even if these radios belatedly make it to the front lines, they will represent a profound failure of the Pentagon’s original vision of a universal radio.