Helicopter operations in the U.S. fall under new FAA 5G restrictions as detailed in airworthiness directive (AD) 2023-11-07, effective June 30. The date of the restrictions reflects that on or after July 1 up to 21 wireless companies are expected to “power up” their 5G C-band cellphone network transmitters.
Restrictions had been previously in place via an ever-expanding list of notams only in areas of proven 5G C-band interference with radio altimeters (radalts) and via an earlier AD, 2021-23-13, which the new AD supersedes. Under the new AD, operators must replace legacy radalts with new ones that meet newly-established minimum performance standards or update their rotorcraft flight manuals (RFM) to reflect the previously established flight limitations.
Those limitations prohibit using radalt minimums for offshore approaches and instead using barometric limitations; using autopilot hover mode that requires radalt data; engaging search and rescue autopilot modes that use radalt data; and performance of any takeoffs or landings in accordance with any procedure in the RFM or OpsSpecs with radalt data. Helicopter air ambulance operators using night vision goggles are exempt (Exemption No. 18973B).
The AD applies to contiguous U.S. airspace including the 12-mile air defense identification zone, but the FAA notes that 5G C-band interference could extend to up to 20 miles beyond these boundaries. Installing new filters to modify existing radalts can cost up to $10,040. A new radalt carries a price of up to $40,000, according to the Helicopter Association International (HAI). The organization noted that the current draft of the FAA reauthorization bill in Congress provides for a grant system to assist operators with these costs, but final enactment is not assured.
The new AD was developed in cooperation with a variety of aviation organizations including the HAI. “Since 2017, HAI has been working closely on the 5G spectrum issue with regulators and a large group of industry stakeholders, including helicopter operators, OEMs, and radio altimeter manufacturers,” said John Shea, HAI senior director of government affairs. “When the FAA issued the notice of proposed rulemaking, we were able to quickly coalesce on several fundamental issues in our filing.”