January 21, 2022 ( updated January 23)   Major U.S. passenger and cargo airlines have  predicted an aviation crisis  if  telecom operators  launch new 5G services near airports
Their fear: the new 5G services in the  C band, will interfere with  instruments such as altimeters, which measure the height  above the ground of an airplane.  Such instruments  work in the 4.2-4.4 GHz which is  to close to the frequency band that 5G services  in the US will use. Altimeters are also used to  achieve automated landings.
US telecom players like Verizon and AT&T point out that the same C Band is used  to roll out 5G in over 40 countries – and no one objected. However they have agreed to keep buffer zones around airport free of 5G services on a trial basis for 6 months to study the problem.  These US telecom companies have bought spectrum in the 3.7-3.98 GHz range  of the C band to roll out 5G.
Hoewever the panic-type  warnings of the U.S. Federal Aviation Administration (FAA)  has resulted in many flight calculations.  
Air India  initially announced  that  flights departing from India and arriving at U.S. airports including the  New York Kennedy International Airport, Newark Liberty International Airport,  Chicago O'Hare International Airport and San Francisco International Airport would be cancelled.
Emirates airline cancelled U.S. -bound flights due to "operational concerns associated with the planned deployment of 5G mobile network services in the U.S."
But yesterday, Air India indicated  was resuming flights to the three of its four US destinations ( NY, Chicago and SanFrancisco)  and after Boeing, whose 777  aircraft it used for  mosrt of its US long haul flights had assured that their altimeters would not be affected.
Different countries  allocate different frequencies for 5G services. In  the Europe Union  telecom companies use 3.4-3.8 GHz range, a lower frequency than the service set to be rolled out in the United States and hence unlikely  to affect aircraft altimeters. France uses  3.6 to 3.8 GHZ GHz which is also safely separated  from the band used by altimeters.
In India the 5G band likely to be used is 3.3 GHz- 3.67GHz, allowing a comfortable gap of 530 MHz with the frequency used by most aircraft altimeters. On January 22, the Times of India quotes the chairman of Telecom Regulatory Authority saying: "India will have no poblem.. for the aviation industry within India over 5G spectrum rollout."
Auction of 5G spectrum is liekely to happen in India this year.