Executives from both Boeing and Airbus have joined the chorus of airline executives calling for a halt to the rollout of C-band 5G.

As WebProNews has covered extensively, C-band is in the mid-band range of available spectrum for 5G, and is considered the sweet spot for speed, coverage, and penetration. Verizon and AT&T coughed up more than $68 billion for C-band spectrum, only to have the airline industry raise concerns the spectrum is too close to that used by aircraft altimeters.

The FAA weighed in with new guidance limiting the use of those altimeters in low visibility conditions over fear of interference. Those efforts only raised more concerns, with United Airlines CEO saying continued rollout of the spectrum “would be a catastrophic failure of government.”

According to Reuters, Boeing and Airbus executives are weighing in, sending a joint letter to Transportation Secretary Pete Buttigieg.

“5G interference could adversely affect the ability of aircraft to safely operate,” the letter said, adding the rollout could have “an enormous negative impact on the aviation industry.”