After stalling for almost two years, FAA cleared 78% of planes in the past week. //

These statements marked a sudden shift, coming just three days after Parker and Kirby signed a letter claiming that 5G on the C-band would cause "catastrophic disruption" to air travel. //

The biggest recent development is that the FAA finally started a process to evaluate and approve altimeters after claiming without proof that 5G on C-Band spectrum (3.7 to 3.98 GHz) would disrupt altimeters that use spectrum from 4.2 GHz to 4.4 GHz. While the Federal Communications Commission created a 220 MHz guard band to protect airplane equipment, poorly built altimeters may be unable to filter out transmissions from other spectrum bands.

The FAA didn't start its process of evaluating the actual altimeters used by airplanes after February 2020, when the Federal Communications Commission approved the use of C-Band spectrum for 5G. The FAA also didn't start this evaluation process after the FCC auctioned off the spectrum to wireless carriers in February 2021. Instead, the FAA continued arguing that 5G deployment should be blocked long after carriers started preparing their equipment and towers to use the C-band. //

The FAA saying that deployment at these frequencies might cause problems doesn't make any sense at all because its already been done. Is the US some special case where laws of physics don't apply?

As someone joked in another post, metric vs imperial wavelengths? //

The FAA could have been in CYA mode even three months ago and had 99.9% of aircraft cleared prior to the Jan 17th go live date. They didn't even start to do their job until Jan 4th. I would point out the original go live date was 1 Nov so the FAA got a homework extension twice and still didn't turn it in on time. //

The FAA came up with a testing regime this year and now we've got most altimeters in use having been cleared, just 3 weeks later. The resources it and the airline industry spent fighting 5G C-band deployment seem quite clearly to far exceed the resources it spent on testing and discovering there's actually no problem. //

I can't help but think that some airline CEOs tinfoil hat wearing, 5G conspiracist brother-in-law got a hold of them at a holiday get together to let him know of the imminent air disaster due to the 5G transmitters and now caused this ridiculousness for the past several weeks.