Groups representing airlines and aircraft manufacturers have asked the Biden Administration to further delay the launch of 5G in the C-Band spectrum, and are asking mobile network operators to join them in finding ways to mitigate the possibility of 5G interference with radio altimeters.

A coalition of 21 companies and airline industry groups has asked the US president’s National Economic Council (NEC) to “convene a joint industry working group to bring the aviation and telecommunications industries together”. In a letter, the coalition states the airline industry wants to find a way to ensure “radio altimeters operate accurately while allowing 5G to roll out safely”.

Last week, AT&T and Verizon both voluntarily delayed their C-Band rollouts, initially scheduled for 5 December. Also last week, the Federal Aviation Administration (FAA) issued a Special Airworthiness Information Bulletin (SAIB) in anticipation of the C-Band transmissions.

The bulletin recommends that radio altimeter manufacturers, aircraft manufacturers, and airlines submit to the FAA information about their altimeters and perform additional tests.

“Further FAA actions beyond this SAIB may still be necessary to ensure safety”, the airline representatives wrote to the NEC. “These FAA actions will have enormous economic impacts that the country cannot face, resulting in needless supply chain delays and travel and shipping cancellations”.

Radio altimeters are used by the airline industry in the 4.2GHz to 4.4GHz band. AT&T and Verizon are set to launch 5G in the 3.7GHz to 3.98GHz band, but the C-Band n77 spans 3.3GHz to 4.2GHz, meaning that future 5G transmissions could use the higher part of the band.

The FAA bulletin acknowledged other countries are already deploying wireless networks in the C-Band, but noted operators in some of these countries have “implemented temporary technical, regulatory and operational mitigations, including temporary proximity and power restrictions, on wireless broadband networks operating in bands”.

The airline industry wants the US cellular industry to also take action to mitigate the possibility of interference. Its letter states “mitigations by the cellular industry” are necessary to “maintain the current level of public safety”.

The coalition’s letter also states the airline industry is committed to developing new standards and equipment in order to reduce potential interference, adding that the industry needs more time and “detailed knowledge of the C-Band” in order to do this.

AT&T stated last week it is already working with both the FAA and the Federal Communications Commission to understand this issue, and emphasised the need to rely on data and science in determining the best course of action.