Any new rule targeting potential 5-G C-band transmission interference with radio altimeters in helicopters needs to balance safety with operational impact, according to Helicopter Association International (HAI).
HAI’s comments come days after the FAA issued a notice of proposed rulemaking (NPRM) regarding the impact of 5G C-band transmissions on helicopters equipped with radio altimeters, which are also sometimes called radar altimeters.
For years wireless communication companies have been pushing the need for 5G C-band transmissions to handle the increase in wireless communications. There has been concern that 5G transmissions can interfere with the operation of radio altimeters, a device on many aircraft that provides pilots with information about the proximity of the aircraft to the ground. Radio altimeters are critical in low-visibility situations.
On April 12, the FAA released the NPRM on a proposed airworthiness directive designed to protect some 1,100 helicopters in the United States from 5G interference. According to John Shea, director of government affairs for HAI, the association is carefully reading the NPRM, and looking for a way that supports both safety and the mission of helicopters.
“At HAI, we understand and appreciate the FAA’s responsibility to ensure safety of the national airspace system for all its users. We are committed to working with the FAA on maintaining aviation safety in a 5G environment,” Shea said.
“It is important to recognize that the degree of dependence on a radar altimeter for safe helicopter operation can vary significantly based on the type of operation,” he added. “The FAA acknowledged this fact when establishing flight restrictions in their initial [airworthiness directive] AD. The recently published NPRM further acknowledges this by presenting operators with the choice to retrofit or to continue operating under the flight restrictions.”
Shea added that HAI is in the process of reviewing the NPRM that would replace the 5G-related AD for rotorcraft, adding, “In the coming days, HAI will submit public comments on the NPRM in the federal register. At that time, we will also release a statement summarizing our positions.”
According to Shea, the NPRM “establishes an interference tolerance threshold for radio altimeters on rotorcraft. Operators who retrofit their equipment to meet the threshold will not be subject to the flight restrictions in the AD, whereas those who do not retrofit will be subject to restrictions throughout the contiguous United States.”
The challenge, says Shea, is that there needs to be a balancing act between safety and operational impact of regulatory action, as helicopters are essential support in critical industries such as law enforcement, construction, and national security.
“Therefore, any revisions to the AD must be both effective and reasonable. Any undue financial or operational hardships imposed on the helicopter industry could have substantial downstream consequences for the vital industries and emergency response entities we serve.”
Per the FAA, the AD is for all helicopters equipped with a radar altimeter due to the potential for 5G C-band interference.
“This proposed AD would supersede a 2021 AD because the FAA determined additional limitations are needed due to the continued deployment of new 5G C-Band base stations.” the FAA states. “It requires revising the rotorcraft flight manual to prohibit certain operations that require radar altimeter data. The AD would require the rotorcraft flight manual revision on or before June 30, 2023.”
As previously reported in FLYING, multiple airports have Notices to Air Missions (NOTAMs) warning pilots about the potential impact of 5G transmission in their vicinity. In January 2022, the wireless companies voluntarily reduced the power of the 5G towers near airports to help protect air traffic while the industry focused on developing protections against interference.
The FAA noted that both AT&T and Verizon agreed to keep their voluntary mitigations in place until July 2023 to give the aviation industry an additional year to retrofit their airplanes with radio frequency filters.
The airlines have until 2024 to make upgrades to comply with 5G per an FAA AD. The proposed AD requires passenger and cargo aircraft in the U.S. to be equipped with 5G C-Band tolerant altimeters by next February.
