As India’s telecom operators prepare to launch 5G services, the country’s aviation safety regulator has written to the telecom department concerned about potential interference of the 5G C-Band spectrum with aircraft radio altimeters, The Indian Express has learned.
A radio altimeter is an instrument that provides direct information about the altitude above the ground for various aircraft systems. The main concern of the Directorate General of Civil Aviation (DGCA) stems from the fact that these altimeters as well as part of the 5G telecom services operate in the C band.
For telecom service providers, C-Band offers a great place to deploy 5G services, ensuring coverage as well as higher bandwidth, resulting in faster internet speeds. For aircraft operations, the use of altimeters in this range ensures very accurate measurements of the aircraft’s altitude.
“The DGCA is working in close coordination with the Department of Communications (DoT) and has informed them of its concerns about possible interference of the 5G C-Band spectrum with aircraft radio altimeters,” said a senior government official.
These red flags are based on concerns raised by the US Federal Aviation Administration (FAA) over the past year since US carriers, such as AT&T, Verizon, T-Mobile and others, began rolling out 5G services. In the US, an agreement between the Federal Aviation Administration and telecom operators has delayed the deployment of 5G services in the C-band near airports that have been assessed as difficult for pilots to take a visual approach.
Radio altimeters pick up the faintest of ground-reflected signals at designated frequencies to achieve highly accurate results. This makes it possible for the instruments to pick up what are known as “out of band” signals. Another official said these out-of-band signals could significantly impair the functionality of the radio altimeter.
However, a third DoT official played down the impact. We have auctioned C-band spectrum in frequency range from 3.3 GHz to 3.6 GHz (in India). Aircraft radio altimeters mainly use frequencies ranging from 4.2 to 4.4 GHz. Therefore, there is a large 500MHz gap between the two frequency bands. Having said that, the Communications Department has noted the concerns indicated by the DGCA, and we are working together,” the official said.
In the US, the official said, the issue is becoming significant because operators there are deploying 5G services at frequencies of 3.7-3.98GHz, which are closer to radio altimeter frequencies.
the news | Click to get the best explanation of the day in your inbox
The DGCA and DOT did not respond to emails sent by The Indian Express, seeking their comments.
Earlier this year, Air India was forced to cancel some of its flights to the US as airlines globally scrambled to reschedule flights amid concerns that the rollout of 5G mobile services in the US could interfere with air navigation systems. Even at that time, the Directorate General of Civil Aviation had coordinated with Indian airlines on the issue.
Over the past year, the Federal Aviation Administration (FAA) has issued several directives for airlines to install certain filters or modify their equipment to ensure that 5G broadcast waves do not interfere with their navigation systems.