MY 2 CENTS By Randy Rowles


RADAR ALTIMETERS AND 5G EXEMPTIONS


The introduction of radar (also known as radio) altimeters to the helicopter industry began as a highly accurate tool to validate actual height above ground during


Instrument Flight Rules (IFR)


flight operations. Like the fixed-wing world, a helicopter being flown on an IFR approach needs accurate information on height above ground to continue to a safe landing.


As the helicopter industry introduced additional technologies, the requirement for a radar


altimeter in a helicopter


expanded. The Federal Aviation Administration (FAA) determined that a radar altimeter would be required equipment for NVG modified cockpits and


stated accordingly in 14 CFR


91.205(h)(7). After April 24, 2017, the FAA expanded the requirement for radar altimeter installation and use in Part 135 operations with the introduction of 14 CFR Part 135.160(a): Radio Altimeters for Rotorcraft Operations.


The clear intent of the regulation was to improve aviation safety. Providing the pilot with a highly accurate tool to know their actual height above ground would reduce controlled flight into terrain (CFIT) accidents.


In 2015, the FAA and the world aviation industry jointly raised concerns regarding 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.


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 also was a major issue for radar altimeter usage in aircraft, the FAA drafted a letter asking for an auction postponement so it could collaborate on a solution. But the National


8 Jan/Feb 2024 (NTIA),


FOR SAFETY OR CONVENIENCE?


Telecommunications and Information Administration


the federal


government’s coordinator on spectrum disputes, failed to put the FAA request to postpone the auction into the FCC’s docket.


In the United States, 5G C-Band services launched in 46 markets on Jan. 19, 2022, all but ignoring the FAA’s concerns on 5G implementation. In response, the FAA established 5G airworthiness directives addressing modifications to the regulatory utilization of radar altimeter equipment in helicopters.


The FAA states that safety is its mission, and safety guides all its decisions. I believe this to be true; however, it seems that common sense is not always included, at least initially.


The FAA requirement for a radar altimeter during NVG and Part 135 operations was a safety-based mandate. During FAA evaluation of early NVG cockpit modifications, FAA test pilots said no NVG flights should occur without a radar altimeter. The FAA’s decision for all Part 135 helicopter operators to install a radar altimeter for continued operations was again a critical safety decision. On both points, I will agree the intent of the FAA’s decision was its belief that a safety issue exists.


Once the 5G rollout began, the FAA issued Airworthiness Directives addressing radar altimeter usage in 5G affected areas. Since that time, the FAA has expanded its definition of 5G affected areas to say that the entire 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. The Helicopter Association International (HAI) soon filed a 5G


exemption request that was crafted to benefit all of HAI’s helicopter operator members. But the FAA exempted only helicopter air ambulance (HAA) operators. Additional exemption requests were submitted and approved for NVG pilot training that included FAA inspectors and HAA operators, to name a few.


It was the limited FAA 5G exemption language, although with the best of intent, that seemed to lack common sense.


For instance, 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.


Within the FAA’s exemption documents, the FAA outlines its belief that a radar altimeter is expected to be inaccurate and thus exempt from the regulatory requirements of 14 CFR Part 135.160(a). As a Part 135 operator, our company spent


thousands of dollars equipping


our helicopters with radar altimeter equipment. Why was this investment so critical to safety if the FAA expected it to have inaccurate readings? We can continue Part 135 flight operations since the FAA stated within 5G exemption language that a radar altimeter may be inaccurate, however, this perspective from the FAA on what was such a critical piece of safety equipment makes no sense.


Since we also operate with NVGs under Part 135 in most of our aircraft, a radar altimeter solution is required for those operations as well. In this situation,


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