Interior Grounded T-Hawk Drones After Identifying Frequency Interference Issues

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By Rachel Leven

March 31 — The Interior Department grounded for months 22 unmanned aircraft systems that were being used to research, monitor and inspect the environment, according to e-mails obtained by Bloomberg BNA through the Freedom of Information Act.

The systems, which had been in use since late 2011, were grounded in February 2014 after it was discovered that the radios were set to the wrong frequency bands. Using the wrong frequency band could raise interference issues; however, there were no related safety issues.

There was “negligible” impact on the department’s operations, and no penalties were imposed on Interior for the frequency issues, Brad Koeckeritz, an unmanned aircraft system specialist for the Interior’s Office of Aviation Services, told Bloomberg BNA March 31. There is now one new radio available for use across this fleet of systems—but that appears adequate for current operations, he said.

“Not sure where the mix-up happened,” Koeckeritz said in a Feb. 14, 2014, e-mail. “It's a bummer, but at least we discovered it before we had a problem.”

The T-Hawk grounding came at a critical juncture for the Interior unmanned systems program, as the department is weighing which technology will be most useful in an unmanned system for environmental projects. The T-Hawks have been used in a “test and operational process” that is helping the department determine specifications for future system purchases, Koeckeritz told Bloomberg BNA.

Interior Unmanned Aircraft Projects 

The Interior Department has flown more than 300 hours since 2010 with the small unmanned systems, another Interior Department official told Bloomberg BNA.

These systems—drones not used for military purposes—have been used for purposes ranging from climate change research to abandoned coal mine investigations across the country.

The department uses RQ-11A Raven aircraft (three to a system) and RQ-16A T-Hawk aircraft (two to a system). Ravens are battery-powered with light fixed wings; T-Hawks are gas-powered with heavier rotary wings.

The use of these systems has provided several benefits, including saving the department money and providing for safer environmental research—such as sending an umanned system in and out of a volcano, Koeckeritz told Bloomberg BNA.

The 22 T-Hawk systems, built by Honeywell International Inc. and worth $10.8 million, were loaned to Interior by the Defense Department in 2012. Interior “took ownership” of the systems in late 2013, according to department e-mails obtained through the FOIA request.

“T-Hawks were just a bridge in our test and evaluation program for U.A.S.,” Koeckeritz told Bloomberg BNA.

Interior T-Hawk Use 

The T-Hawks were used in 31 training sessions and missions starting in late 2011, Koeckeritz said.

However, Koeckeritz told Bloomberg BNA he discovered Feb. 14, 2014, that the drones were set to incorrect frequencies when he went to view the aircraft at an Interior warehouse to consider options for retrofitting them. Koeckeritz announced in an e-mail the same day that the systems would be grounded.

The frequency bands were operating on a “M1 band” that can only be used for this equipment outside of the continental U.S., a 1625 to 1725 megahertz range rather than an acceptable “M2 band” in the 1755 to 1850 MHz range, Koeckeritz said.

The 1625 to 1725 MHz spectrum bands are used for several purposes in the U.S., including for broadband, phones, satellites and space research services, according to the Federal Communications Commission. The M2 band is “allocated for exclusive Federal Government use” of unlicensed, low power transmitters, according to the FCC.

Interior worked with the National Telecommunications and Information Administration collaboratively to resolve the issue, Koeckeritz told Bloomberg BNA.

Michael Hutt, then a staff member in the USGS National Unmanned Aircraft System Project Office, expressed frustration that the systems couldn't be used—“your kidding,” he said in an e-mail responding to Koeckeritz—and requested additional tests to be sure that none of the T-Hawks were available for use.

“Believe me, I wouldn't have sent that e-mail if I wasn't sure,” Koeckeritz replied Feb. 14, 2014.

New Versus Legacy Systems 

Over the following days and weeks, Interior staff debated whether retrofitting the T-Hawks—considered “legacy” systems—was economical or whether the department would be better off investing in new, commercial systems.

Hutt on Feb. 19, 2014, pointed to issues with the T-Hawk systems separate from the grounding-frequency band issue. He listed “hazmat, noise, [and] altitude limitation” as some issues that had arisen with the T-Hawks.

New systems’ user interfaces, versatility, and capabilities of commercial systems “have surpassed many of the legacy systems we are currently using,” Hutt said in the e-mail.

Hutt sent the message to Koeckeritz and 10 Interior staffers from Fish and Wildlife Service, USGS, the Office of Surface Mining Reclamation and Enforcement, the Bureau of Reclamation and the National Park Service.

“I agree with Lance and Mike, there are some far less expensive and problematic systems now available,” Jim Traub, then a National Park Service National Fleet and Pilot Aviation Specialist within the Fire Management Program Center, responded by e-mail the same day.

“Time to look at the next gen and move past several issues, frequency, parts, complexity, sensors and interchangeability, number of system operators,” Traub said.

In the meantime, the Interior’s Office of Aviation Services bought appropriate radio technology for one T-Hawk system and tested the system June 18, 2014, Koeckeritz said in the Oct. 5 e-mail.

No ‘Conflicting Demand.'

The test was successful, and that radio has been passed around to be used with other T-Hawk systems as the department looks for other options to retrofit the T-Hawks, Koeckeritz told Bloomberg BNA. There hasn’t been “conflicting demand” for the radio, and transferring the radio has been easy, he said.

“We can go back and purchase another one at any time,” Koeckeritz told Bloomberg BNA, saying he hasn’t received such a request.

Ultimately, the department chose to retrofit its existing T-Hawk fleet and is also looking to purchase new systems.

Initially, the department had expected to pay $22,000 per system to retrofit the T-Hawk system; however, the department found a company that would search for solutions to retrofit each T-Hawk system for closer to $5,000, according to the e-mail.

The department signed an “indefinite delivery, indefinite quantity” contract that “may not exceed $150,000” in August 2014 with Avid LLC, an aeronautical engineering company, to find a solution and retrofit the T-Hawks.

The contract, which took effect Aug. 25, 2014, and ends Aug. 24, 2019, was to purchase radios and have them installed in the remaining T-Hawks, according to contract documents obtained by Bloomberg BNA.

“This is a 75% decrease in the price of radios and will give us much more flexibility in using these aircraft,” Koeckeritz said in the Oct. 5, 2014, e-mail. “Additionally the … radios should allow us better resolution of the video which will help the bureaus more effectively conduct their missions.”

Avid is still working on the Interior contract, and the department hasn’t “taken delivery” from them yet, Koeckeritz told Bloomberg BNA.

New Solutions 

As to new solutions, Koeckeritz told Bloomberg BNA that Interior will soon finalize its request for new systems.

The department is working to finalize what specifications are needed in future aircraft purchases, in part informed by data from these T-Hawk uses, and expects to release in late summer or early fall a request for an “indefinite delivery, indefinite quantity” contract, Koeckeritz said.

That type of contract would allow the department to purchase one or two aircraft initially and have the ability to purchase several more during a certain time frame, he said.

To contact the reporter on this story: Rachel Leven in Washington at

To contact the editor responsible for this story: Larry Pearl at


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