Already a member? Please login below for an enhanced experience. Not a member? Join today

FAA questions compliance of some NavWorx UATs

Certain ADS600-B units don’t meet TSO specs, agency says

The FAA issued an unapproved parts notification Oct. 14 affecting specific NavWorx, Inc. model ADS600-B remote-mounted universal access transceivers (UATs). The products provide Automatic Dependent Surveillance-Broadcast (ADS-B) Out and In on the 978 MHz frequency.

Technicians at Propellerhead Aviation measure to determine the proper location for a universal access transceiver antenna. They are installing Automatic Dependent Surveillance-Broadcast in a Cessna 152. Photo by Mike Collins.

NavWorx part numbers 200-0012 and 200-0013, with software release 4.0.6 through 4.1.0, are affected by the notification. The unapproved parts notification follows reports from aircraft owners that the NavWorx UATs could not be selected in the FAA’s online ADS-B rebate application form.

An FAA investigation determined that those ADS600-B UATs, delivered or updated with the specified software releases, do not meet the minimum performance standards specified in TSO C-154c—even if they are marked with the TSO number and all markings specifically required by that TSO, according to the FAA’s unapproved part notification. The TSO establishes specifications for ADS-B equipment operating on the 978 MHz UAT frequency.

“These models indicate that they are broadcasting with the integrity required by 14 CFR 91.227; however, they contain an internal commercial GPS unit that has not been shown to meet the ADS-B Out performance requirements of 14 CFR 91.227,” the FAA said in its notification. “As a result, the operation of these units could result in an unsafe condition in the national airspace system due to the transmission of inaccurate aircraft position data.” NavWorx ADS600-B UATs with part numbers 200-0112 and 200-0113 contain an approved GPS position source and are not covered by the notice, according to the FAA.

The FAA recommends that affected NavWorx UATs installed in an aircraft not be operated, and should be removed or deactivated, the notification states.

“The products are designed and were tested and manufactured to meet the 2020 rule,” NavWorx said in a statement provided Oct. 17 by NavWorx President Bill Moffitt. “We are working with the FAA to rescind the UPN and get the product established on the FAA rebate website. We remain committed to supporting our present and future customers.

“FAA certified our products three years ago,” the NavWorx statement continued. “At that time our testing demonstrated that the products’ GPS module met 91.227(c) integrity. Nevertheless, the FAA required that we output at an integrity level lower than our testing demonstrated. But, even with the lower integrity output, the FAA assured us the products would receive traffic. Unfortunately, this January the FAA changed their system to stop sending traffic to our products for reasons unconnected to the performance or integrity of our products.

“By changing their system after issuing certification of our products, the FAA knowingly and intentionally modified the functionality of our products in a manner that deprived our customers of information intended to improve safety in the NAS. NavWorx notified the FAA of this problem and for some time has been working with the FAA to address this issue to maintain NAS safety.”

“AOPA is still monitoring the situation, but at this stage, this is a commercial issue that NavWorx needs to address with its customers,” said Justin Barkowski, AOPA director of regulatory issues.

Mike Collins

Mike Collins

Technical Editor
Mike Collins, AOPA technical editor and director of business development, died at age 59 on February 25, 2021. He was an integral part of the AOPA Media team for nearly 30 years, and held many key editorial roles at AOPA Pilot, Flight Training, and AOPA Online. He was a gifted writer, editor, photographer, audio storyteller, and videographer, and was an instrument-rated pilot and drone pilot.
Topics: Avionics, ADSB

Related Articles