Regulatory Alert: AAAE Responds to FAA’s Proposed Aircraft Altimeter Retrofit Requirements
March 10, 2026
Yesterday, AAAE submitted comments in response to the Federal Aviation Administration’s (FAA) proposed rule that would require all legacy aircraft equipped with radio altimeters to upgrade or retrofit their altimeters to ensure they can withstand potential interference from 5G and other advanced wireless signals. Under the proposal, all aircraft operating under Part 121 or Part 129 would have to meet the new requirements sometime between 2029 and 2032. All other aircraft with radio altimeters would have to comply within two years thereafter.
In our comments, AAAE expressed support for a permanent solution that allows advanced wireless networks, such as 5G, to safely co-exist with aviation and that does not negatively impact airport operations. To achieve that goal, we urged FAA to establish reasonable deadlines for operators of over 12,500 aircraft to retrofit their radio altimeters, recognizing that significant challenges exist to complete the transition. AAAE also encouraged FAA to work with the appropriate telecommunications companies to ensure that current mitigation measures—implemented by the companies to address potential interference from existing 5G networks with radio altimeters—remain in place until such time as air carriers can upgrade their aircraft.
You can read AAAE’s comments here.
Background. For years, AAAE has engaged with FAA to address concerns over the potential interference of wireless signals with radio altimeters in aircraft in order to mitigate possible operational disruptions at airports. In 2022, Verizon, AT&T, and other companies took steps to deploy their 5G networks in the 3.70–3.98 GHz frequency band (known as the Lower C-Band). FAA and the aviation community raised concerns that the networks in the Lower C-Band could negatively interfere with radio altimeters, which use signals in the nearby 4.2–4.4 GHz frequency band (known as the RA Band). Ultimately, the telecommunications companies agreed to implement measures to mitigate potential interference through January 2028.
Status Update and FAA’s Proposed Rule. Under the One Big Beautiful Bill Act of 2025, Congress required the Federal Communications Commission (FCC) to auction a certain amount of spectrum in the 3.98–4.2 GHz frequency band (known as Upper C-Band), which is intended to be used by telecommunications companies in a similar manner as the Lower C-Band. Recently, FAA has raised concerns that wireless signals from the Upper C-Band and Lower C-Band (when the voluntary mitigation measures cease in 2028) pose a risk of interfering with radio altimeters, with signals from the Upper C-Band being more problematic because of their adjacency to the RA Band.
To address these concerns, FAA proposed a rule in January that would require all radio altimeters on aircraft to meet minimum performance requirements that ensure the equipment can withstand wireless signals from both the Upper C-Band and Lower C-Band. Any aircraft operating under Part 121 or Part 129 would have to meet the new requirements by the date the FCC authorizes wireless services in the Upper C-Band, which is expected to occur between 2029 and 2032. All other aircraft with radio altimeters would have to comply within two years after the deadline applicable to aircraft operating under Part 121 and Part 129.
Summary of AAAE’s Comments. For years, AAAE has supported FAA finding a permanent solution to address the potential interference posed by advanced wireless networks to aviation safety. While AAAE did not weigh in on the specific radio altimeter requirements or performance standards, we urged FAA to ensure that the deadlines established for operators to retrofit their aircraft must account for the significant certification, production, and logistical challenges that remain. Similar comments and recommendations were submitted by airlines and manufacturers. Realistic and reasonable deadlines are necessary to ensure no disruptions to airport operations and air service occur.
While equipping all legacy aircraft with the next generation of radio altimeters would provide the permanent solution needed, many telecommunications companies are already implementing their 5G networks using the Lower C-Band. The mitigations implemented by these companies to address potential interference with radio altimeters caused by these networks are scheduled to sunset in January 2028, which is before operators are expected to have upgraded their altimeters. In our comments, AAAE encouraged FAA to work with the telecommunications companies to ensure that these mitigations remain in place until the date by which radio altimeters must be upgraded. This is to ensure that the risks posed by the networks using the Lower C-Band do not negatively impact aviation safety.
What’s Next? FAA will begin to review and adjudicate 46 comments that the agency received in response to the proposed rule. FAA will eventually have to issue a final rule and establish deadlines for operators of legacy aircraft with radio altimeters to complete their upgrades. In the meantime, AAAE will be working with our members and industry partners to ensure that operational disruptions are minimized, and FAA develops and implements a permanent solution that allows aviation and the 5G C-Band networks to safely co-exist.
