'We have informed the government multiple times that the situation in the US and India are different.'
'Here, there will be a 500 MHz gap in the frequencies which will safely allow aviation without interference.'
In the face of 5G expansion, the Directorate General of Civil Aviation (DGCA) is ready to make it mandatory for all airlines to replace radio altimeters (RAs) on their aircraft, according to government officials.
This move is designed to facilitate setting up of 5G base stations near airports.
In November 2022, the Department of Telecommunications (DoT) had directed major telecom operators -- Bharti Airtel, Reliance Jio, and Vodafone Idea -- to refrain from setting up 5G base stations operating in the 3,300-3, 670MHz frequency range, also known as the C-band, within certain zones near airports.
These zones extend 2,100 metres from both ends of the runway and 910 metres from the centreline of the runway. These restrictions were put in place due to potential interference between 5G emissions and airplane RAs.
DoT further stipulated that 5G base stations within a 540-metre perimeter of these zones limit their power in the 3,300 to 3,670MHz range to 58 decibel-milliwatts (dBm). These restrictions would remain until all aircraft have upgraded RAs, government officials said.
A month later, in December 2022, the DGCA instructed all airlines to work with aircraft and RA manufacturers to replace RAs, the officials noted. During subsequent meetings, Boeing and Airbus communicated that new RAs for Indian planes would only be available from 2024.
Boeing informed the Indian government that it would first retrofit its approximately 4,500 operational planes in the US (1,500 of those were retrofitted until April 2023), they said.
The company aims to finish retrofitting all US planes by March 2024.
Airbus disclosed that its A320 family planes operating in India, equipped with RAs from French company Thales, would undergo retrofitting. The European aircraft maker also noted the availability of upgraded Thales RA models.
Sector-wide impact
The retrofitting process will impact the majority of commercial planes operating in India. However, some planes, including all B787s and B777s in Air India's fleet, already have new RAs.
According to Air India executives, retrofitting an RA is an overnight process and does not affect an airline's flight schedule.
They also said that talks with RA manufacturers for retrofitting RAs on A320 family planes are at an advanced stage.
The airline has 129 planes in its fleet. About 39 per cent of its fleet consists of B787s and B777s. The remaining planes in its fleet are of the A320 family.
As on August 1 2023, India had a total of 647 commercial aircraft, with Airbus and Boeing accounting for 68 per cent and 22 per cent respectively, according to aviation analytics firm Cirium.
According to aviation industry sources, airlines will have to bear the cost of the replacement of RAs. However, at this stage, it is unclear what the final cost will be, they said.
With DoT repeatedly urging the aviation regulator to set a clear timeline for replacing RAs on all planes in India, DGCA had extensive discussions with Indian carriers.
Following these talks, DGCA has decided to ask all carriers in the country to install modified RAs on their planes.
The officials cited above revealed that DGCA has already sent a proposal on this matter to the MoCA for a final decision.
Meanwhile, the regulator has also asked Airbus and Boeing to provide a timeline for the replacement of RAs on planes operating in India.
Airbus informed the government that 5G emissions between 3,700MHz and 3,980MHz can impact radio altimeters at specific power levels, elevation, and tilting of 5G antennas, the officials said.
In January 2023, US aviation regulator Federal Aviation Administration reported over 420 instances of anomalies in radio altimeters in areas where 5G C-band had been deployed.
In nearly 100 of these cases, the FAA was unable to rule out the possibility of 5G emissions interfering with RAs.
Telcos stick to position
Commercial aviation RAs function within the 4,200 to 4,400MHz band, separated by 220 MHz from the 5G C-band transmissions situated in the 3,700 to 3,908GHz band, according to the US aviation regulator.
Telecom industry executives pointed to these FAA guidelines to stress their opposition of the existing ban on 5G base stations.
"We have informed the government multiple times that the situation in the US and India are different. Here, there will be a 500 MHz gap in the frequencies which will safely allow aviation without interference," a telco executive said.
"We have argued that if the government wants to codify the rules, we will work with them," the telco executive added.
The Cellular Operators Association of India, which represents telecom operators, has told the government there should be controlled flight simulations to prove that 5G signals do not interfere in controlling air-borne planes.
It has also pointed out that nearly 40 countries already use 5G in the C-band with no reported impact on aviation services.
Role of radio altimeters
Radio altimeters, or RAs, measure the distance between an aircraft and the ground below.
In conditions of low visibility, they bolster the situational awareness of pilots, providing vital inputs for onboard systems, such as the traffic collision avoidance system.
What's the issue?
In November 2022, telecom operators were barred from setting up 5G base stations near airports over fears of 5G signals interfering with RAs.
Feature Presentation: Ashish Narsale/Rediff.com
