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Radar Altimeters and 5G Exemptions. For Safety or Convenience?

In the January/February issue of RotorPro, Randy Rowles takes a hard look at the aviation industry and the FAA’s concerns, airworthy directives and FAA exemptions for Part 135 pilots and passengers from 2015 through today.

Radar altimeters are critical for helicopter operators to receive accurate information on height above ground for flight and safe landings and are required for all night vision goggle (NVG) operations. However, radar altimeters were affected when the telecommunications industry was permitted to use the high-power frequencies needed for full 5G implementation.

“In 2015, the FAA and the world aviation industry jointly raised concerns regarding the allocation and permitted use by telecom companies of frequencies in the 3.4 to 3.7 GHz spectrum (i.e., 5G) — but not the 3.7 to 3.98 GHz spectrum, that is, the issue for radio altimeters.”

The aviation industry reacted quickly and was highly concerned about safety and the risk that radar altimeters would not be accurate.

“From 2018 to 2020, ahead of the auction for 5G C-Band, the FAA again raised concerns. Then, in 2020, concluding the 5G C-Band was also a major issue for radar altimeter usage in aircraft, the FAA drafted a letter asking for an auction postponement to collaborate on a solution. But the National Telecommunications and Information Administration (NTIA), the federal government’s coordinator on spectrum disputes, failed to put the FAA request to postpone the auction into the FCC’s docket.”

On January 19, 2022, the US launched 5G services in 46 markets, ignoring the FAA’s concerns about aviation safety risks. Therefore, the FAA quickly acted using exemptions for previously required radar altimeter mandates.

“Once the 5G rollout began, the FAA issued Airworthiness Directives addressing radar altimeter usage in 5G affected areas. Since then, the FAA has expanded its definition of 5G affected areas to say that the lower 48 states are now 5G critical….The use of regulatory exemptions was the FAA’s solution to allow flight operations to continue when radar altimeter equipment is required.

While the exemptions were intended to protect operations and public safety, Randy details the limitation of the exceptions, especially when the entire purpose of the radar altimeter is to enhance public safety.

“…the FAA stated that the approval of the HAA 5G exemption was in the best interest of public safety. If true, why weren’t law enforcement, firefighting, and other public safety operations included? Within the initial HAI 5G exemption, most law enforcement agencies that fly with NVGs were forced to do so contrary to regulations, unless they chose to operate as a Public Aircraft Operation due to non-compliant radar altimeters.”

The FAA outlined the radar altimeter inaccuracy in the exemption documents; however, Randy outlines why the exemptions granted to critical, mandated equipment weren’t even making ‘common sense.’

“Here is an example, in the form of a question, where common sense was lacking on the 5G exemption issue: If an HAA operator is exempt from 5G limitations and allowed to fly NVGs for the safety of a single passenger and crew, why would a Part 135 helicopter with nine or fewer passengers have a lesser requirement for safety and be unable to fly NVGs to aid in terrain and weather avoidance?”

The FAA maintained that the exemption process was valid. During the pre-launch of the 5G, FreeFlight Systems took action and developed a new ground-up radar altimeter to mitigate safety concerns and address the 5G interference.

“The FAA states that until 5G radar altimeter solutions are more available, the exemption process is valid. The radar altimeter industry is ready now with 5G solutions. Companies like FreeFlight Systems, a radar altimeter manufacturer, now offer 5G-compliant, software-based radar altimeter solutions for helicopters.

On June 23, 2023, the FAA reissued Exemption Number 18973B to HAI on behalf of the industry. Updates to this exemption took an unexpected turn in the form of a common-sense approach to the 5G challenges the helicopter industry has been facing on the issue. Within the update, the FAA stated, ‘This exemption applies only to Part 91 operators and Part 119 certificate holders authorized to conduct Part 135 operations.’

Randy concludes the article that the FAA exemptions now make more sense and apply to Part 135 and Part 91 operations and expands NVG operational approval from just HAA to anyone operating under Part 91.

Read the full article.

Randy Rowles has been an FAA pilot examiner for 20 years for all helicopter certificates and ratings. He holds an FAA Gold Seal Flight Instructor Certificate, NAFI Master Flight Instructor designation, and was the 2013 recipient of the HAI Flight Instructor of the Year Award. Rowles is currently the owner of the Helicopter Institute.







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The “My 2 Cents” column is published in each edition of RotorPro magazine and copyrighted by JustHelicopters.

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