The FAA intends to pass an altimeter update mandate this summer, but aircraft operators could get rebates for the expense.
The Federal Aviation Administration will soon issue another rule requiring all radio altimeters on US aircraft be updated to prevent interference from 5G transmissions, though cellular companies are likely on the hook to help foot the bill.
That is according to the FAA and the Federal Communications Commission (FCC), which plans in 2027 to begin auctioning radio spectrum in the 3.98-4.14MHz range (the “Upper C-band”) to cellular companies. Those firms intend to use the bandwidth to roll out new 5G networks.
That portion of the spectrum edges close to the 4.2-4.4MHz range used by radio altimeters, creating the risk of interference that can cause a variety of avionics and aircraft systems to malfunction, the FAA says.
In response, the agency in January proposed requiring operators to update all altimeters on all aircraft – some 59,000 units on 41,000 aircraft at an estimated cost of at least $4.5 billion.
A final rule is now imminent.
“Later this summer, the FAA will issue its own rule to require aircraft altimeter upgrades to ensure altimeters can safely operate with signals from the 5G wireless signals that will be auctioned,” the FAA said on 1 July.
The order will be the latest in a string of FAA directives targeting the risk of 5G signals interfering with radio altimeters. As recently as 30 June the FAA issued a rule addressing 5G interference, specific to flights in Canada.
FCC commissioners will also hold a vote on 22 July on a proposal to approve the Upper C-band auctions to cellular firms. That proposal specifies that auction winners help finance the expense of altimeter updates.
It will “ensure a continued successful coexistence between wireless operations throughout the C-band and radio altimeters” and include “establishment of retrofit rebates to support the domestic aviation sector in its efforts to upgrade the performance of these critical safety tools”, the FCC says.
The draft “proposes that winning bidders will be responsible for… rebates for the purchase and installation of upgraded radio altimeters”.
The FCC has not disclosed the dollar amounts of the rebates, citing “the sensitive nature of this type of financial information”. It plans to disclose the figures after the commission vote.
Both the FAA and FCC decline to provide more information.
The 5G interference issue arose several years ago as cellular companies were then preparing to begin using the 3.7-3.98GHz range, called the Lower C-band.
In response, the FAA in 2023 issued orders requiring altimeter updates and prohibiting aircraft from many types of operations at US airports. Cellular companies also agreed to temporarily reduce transmissions at some airports to prevent interference.
But those prior altimeter updates do not make the units resistant to interference from the Upper C-band transmissions cellular companies are now preparing to use.
The FAA’s January proposal calls for airlines to update their altimeters between 2029 and 2032.
Aviation trade groups initially baulked at the timeline, saying any earlier than mid-2032 would be impossible.
But in March the industry changed its tune, saying most altimeters could indeed be modified by 2029 – on condition that airlines receive help paying for the project.
The post Cellular companies set to help foot the cost of 5G-required altimeter updates first appeared on FlightGlobal.