FAA Backs Radar Altimeter 5G Coexistence in FCC C-Band Auction

The FCC will vote on July 22 on an order to auction 160 MHz of spectrum in the upper C-band (3.98 to 4.14 GHz) next year, a move the agency said exceeds the 100-MHz minimum Congress established. The auction would create a contiguous 440-MHz block when combined with the lower C-band (3.7 to 3.98 GHz), which the FCC previously cleared.

The FAA issued a statement saying it is confident that 5G signals from the auction band can safely coexist with aviation “after years of FAA-led testing and technical analysis.” The agency said it worked with the FCC to incorporate safeguards into the auction order, including limiting the power of auctioned 5G signals to levels the FAA has determined are safe for aviation, protecting the radar altimeter band with a buffer band between it and the auctioned frequencies, and limiting the height of 5G transmission towers.

“Additionally, the FCC’s order will ensure the functionality of key altimeter-based alerting systems, including terrain avoidance warning systems,” the FAA said.

In the third quarter, the FAA plans to issue its own rule requiring aircraft radar altimeter upgrades to ensure these devices can operate safely alongside 5G signals from the auctioned spectrum. The FCC order also proposes rebates to support domestic aviation operators and owners in upgrading their altimeters.

FCC Chairman Brendan Carr said the July 22 vote would advance a fast and fair transition for incumbent satellite services and a successful coexistence environment for critical aviation safety systems. “Thanks to the early and close collaboration with the FCC’s federal partners across the Trump Administration—including the Federal Aviation Administration—we are delivering on time, on budget, and with no surprises,” Carr said.

Winning bidders would be permitted to commence upper C-band wireless services in December 2030 for top-75 markets and in the remaining markets starting in July 2031. The FCC said the auction is expected to raise many billions of dollars for the U.S. Treasury.