The Federal Aviation Administration has issued a pair of airworthiness directives based on concerns that potential interference from C-band 5G wireless services could pose a safety risk to air traffic and lead to flight diversions.
According to reports in Reuters, the aviation industry and the FAA have raised concerns about of 5G with sensitive aircraft electronics like radio altimeters. The airworthiness directives call for airplane and helicopter flight manuals to be revised to prohibit some operations requiring radio altimeter data in the presence of C-band wireless signals.
In November, both AT&T and Verizon Communications agreed to push back the commercial rollout of C-band wireless until Jan. 5, to give the companies time to work with the FAA to address the safety concerns.
However despite assurances from the wireless companies that they would take “additional steps to minimize energy coming from 5G base stations,” aviation industry groups maintain the limitations would not be sufficient to address air safety concerns.
One of the FAA directives said the planned use posed an “unsafe condition” that required immediate action before the Jan. 5 deployment “because radio altimeter anomalies that are undetected by the aircraft automation or pilot, particularly close to the ground could lead to loss of continued safe flight and landing.”
Next generation 5G devices can transmit data up to ten times faster than 4G, reaching speeds of over a gigabit of data per second. However the high-frequency band which offers those data rates and speed has a huge capacity but short range.
On the other hand, lower bandwidth frequencies cover a wider area but at the cost of limited capacity. The C-band is a mid-spectrum frequency band located between 3.4GHz and 3.8GHz, and gives 5G carriers a workable compromise between the two.
At this point, it is not clear what specific aircraft or airports may be affected. The FAA said it would publish notices to identify specific areas where 5G C-band wireless broadband signals could impact radio altimeter data.
In a statement, Verizon argued that “there is no evidence that 5G operations using C-band spectrum pose any risk to aviation safety, as the real-world experience in dozens of countries already using this spectrum for 5G confirms.”
The company said it was confident the FAA ultimately will conclude C-Band 5G use “poses no risk to air safety.”
For its part, the FAA said in a statement that the two directives “provide a framework to gather more information to avoid potential effects on aviation safety equipment,” and that the “expansion of 5G and aviation will safely co-exist.”
Currently the FAA is working with the Federal Communications Commission and the Biden administration to lay out the precise limitations of the directives, which are expected to be outlined in a series of notices in the coming weeks.