Hundreds of stranded passengers heaved a huge sigh of relief after the Thursday announcement by Air India to resume operations to key US airports. The national flag carrier had cancelled or rescheduled flights to New York City, San Francisco, Chicago and Newark for two consecutive days over fears of 5G telecom signals potentially interfering with the functioning of aircraft altimeters around those airports.
The altimeter is used in maintaining the distance of the aircraft above the desired or assigned altitude from the surface while in flight. As a principal navigation device on aircraft, the altimeter also facilitates landings in low visibility conditions.
The rollout of the fifth generation or 5G for broadband cellular networks by service providers AT&T and Verizon led the US aviation regulator, Federal Aviation Administration (FAA) to warn that telecom frequencies in a radio spectrum called C-band could hamper the normal functioning of altimeters in certain types of aircraft.
"Because the proposed 5G deployment involves a new combination of power levels, frequencies, proximity to flight operations, and other factors, the FAA will need to impose restrictions on flight operations using certain types of radar altimeter equipment close to antennas in 5G networks," it said in a statement.
With the world's second-largest telecoms market prepping to rollout 5G by the year-end, is similar chaos in the offing at international aviation hubs in the Indian cities of Delhi, Mumbai, Kolkata, Chennai, Bengaluru, Ahmadabad, Hyderabad and Lucknow?
A cross-section of experts that Business Today spoke to summarily ruled out such an eventuality.
"All wireless technologies are typically deployed in a particular part of the spectrum or utilise a certain set of frequencies. Since lower frequencies are expected to be used in India, we are unlikely to face similar issues with 5G rollout," asserted founder at telecoms consultancy ComFirst India, Dr. Mahesh Uppal.
Aircraft around the world use the frequency band 4.2-4.4 GHz for radio altimeters. According to reports, there is a risk of interference to some of the civilian aircraft from 5G systems being licensed in the US within the frequency band 3.7-3.9 GHz.
"In India, there is no risk from 5G services to aircraft and we are fully safeguarded as we are only allocating 3.3-3.6 GHz, which is more than 500 MHz below the altimeter spectrum. Thus, the C-band frequencies that are being auctioned for 5G in India are completely safe and there is no risk to the civil aviation radar altimeters," said Bharat Bhatia, president of the not-for-profit body ITU-APT Foundation of India (IAFI).
Telecom spectrum akin to fabric roll
The spectrum allocation can be better understood using the analogy of a roll of fabric.
"Different countries adopt different parts of the spectrum when they allocate it for different uses. It is equivalent to having a metre of material. You can allocate one metre for a specific use, leave half a metre as a buffer and then allocate the next half metre for another user and again leave half a metre as a buffer," explained former Cellular Operators Association of India (COAI) director general, Rajan Mathews.
"What other countries do is increase the buffer zone - though not an efficient use of spectrum if a country is spectrum-challenged - to prevent spilling over or interference in another user adjoining the spectrum band."
Indian Air Force (IAF) veteran and director of flight operations at the regional carrier IndiaOne Air, Wing Commander Prem Kumar Garg elaborated, "The Ministry of Communications had to restrict the upper-frequency band limit of 5G to an appropriate frequency in band n78, thereby ensuring minimum interference with radio altimeter of aircraft, which operates in 4.2-4.4 GHz band. Since the n78 band is till 3.8 GHz, the likelihood of interference is minimal."
Also known as the 3.5 GHz band or C-band 5G, n78 is the most widely used band in 5G communication.
Experts also feel that the current crisis at US airports could have been avoided through timely intervention.
"As per available information, the US aviation industry has not been sufficiently proactive in this regard. They could have easily raised the issue several months earlier and upgraded equipment on their aircraft. The same aircraft are not facing any problems with the technology in Europe or Japan," pointed out Dr. Uppal.
The experts also agree that aviation safety must be foolproof when 5G technology is introduced in one of the fastest-growing aviation markets globally.
"Learning from ongoing safety concerns for aircraft operations in the US during low visibility operations, all endeavours must be made by appropriate regulatory agencies to conduct adequate trials to rule out any safety concerns before rolling out 5G services in India," surmised Garg.
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