Major airlines expect minimal operational disruption as a result of the FAA rule.
Starting July 1, hundreds of aircraft from US airlines will be restricted from performing low-visibility landings due to the Federal Aviation Administration (FAA) mandate regarding 5G interference with aircraft radio altimeters. Only the aircraft equipped with upgraded or new 5G-tolerant altimeters may perform unrestricted operations. While airlines across the US began upgrading their aircraft last year, many planes haven’t seen the upgrades yet.
The 5G interference problem
While offering increased high-speed data, the 5G cellular network uses a range of frequencies. These frequencies (also known as C-band) have the potential to interfere with radio altimeters used on aircraft. Radio altimeters, which also use C-band frequencies, calculate the aircraft altitude and connect to several critical aircraft systems. The information transmitted through the radio altimeter is critical to automatic landing systems, flight controls, primary displays, crew alerting, and surveillance, just to name a few.
5G situation and recent developments
The US air transport system was threatened by the activation of 5G operations in January 2022. With the potential risk of interference with aircraft radio altimeters, the FAA mandated that the airlines could only operate at affected airports in low (category 2 and 3) visibility under the Alternative Means of Compliance (AMOC) method.
OEMs must establish that the installed radars provide sufficient resilience against C-band interference, especially during low visibility operations. Airlines can also modify existing RADALTs (radio altimeters) or replace them, at their own expense, to enable unrestricted operations.
The AMOC process was intended to be a temporary fix, as communicated by the FAA in May 2022. The FAA required airlines to upgrade or replace radalts to meet the minimum performance level by July 1, 2023. While many operators began the upgrade process across its fleet, current supply chain issues limit the upgrade of all aircraft in time. Not meeting the deadline means potential operational disruptions during one of the busiest travel seasons.
Current progress and potential disruptions
Large carriers in the US are well ahead in their equipment upgrade process. According to the FAA statement on June 30, "More than 85% of the domestic commercial airline fleet and about 66% of the international fleet are equipped with radio altimeters that can operate safely in the US 5G C-band environment."
However, with a very large fleet and expanded operations, some airlines have yet to complete upgrades to their entire fleet. Delta Air Lines will see significant disruptions onboard some aircraft during low visibility operations. The affected aircraft must be constantly rotated to minimize the impact. According to Delta, "Some of our aircraft will have more restrictions for operations in inclement weather. To mitigate long delays, Delta teams have the capability of moving assigned aircraft away from airports that stand to be impacted by weather."
About 190 of Delta Air Lines aircraft lack 5G-tolerant altimeters, including all its Airbus A220s, most A319s and A320s, and some A321s. According to the reports from American Airlines and United Airlines, their entire fleet has been upgraded. However, it is not known if their regional partner airlines have completed all their upgrades.
Both the Airlines for America (A4A) and the Regional Airline Association (RAA) say their member airlines have been updating jets in recent months, but that progress has been hindered by supply chain troubles. This may have operational disruptions, which are being tackled by advanced planning and scheduling.
While some disruptions are expected during the peak travel season, most airlines are confident that their existing capabilities and efficient flight planning will have minimal impact on their schedules.
This article originally appeared on Simple Flying.