A US FAA bulletin says 5G airwaves could interfere with the functioning of an aircraft's radar altimeter, a critical piece of equipment that measures the height of the plane from the ground below.
The US is set for a geographically limited 5G rollout this Christmas, after a bumper $81 billion spectrum auction earlier this year.
Just as the rollout date nears, the US Federal Aviation Administration (FAA) has sounded alarm bells over potentially fatal consequences of 5G interference on aircraft.
Similar consequences could apply in India, where 5G spectrum auction is scheduled in January 2022, with the rollout beginning later next year (though reports suggest impending delays).
A Directorate General of Civil Aviation (DGCA) official said that the regulator was “aware of the FAA bulletin but there was no cause of alarm yet in India”.
No deliberations on the warnings have yet taken place among officials at DGCA.
On November 2, 2021 the FAA issued a Special Airworthiness Information Bulletin (SAIB) that indicated radar altimeters in aircraft could potentially malfunction due to interference from 5G airwaves.
A radar altimeter is a critical piece of equipment that measures the height of the aircraft from the ground below.
These are located at the bottom of the plane’s fuselage and come into play when the aircraft is below 2,500 feet, mostly during takeoff and landing.
It measures the height above the ground by transmitting radio waves that hit the ground and are transmitted back.
This is what seems to be causing consternation in aviation regulatory circles as more nations around the world including the US and India move closer to introducing ultra-high speed 5G internet to their citizens.
The FAA in the report points to a Radio Technical Commission for Aeronautics (RTCA) study on the deleterious impact of 5G radio frequencies in the 3.7 to 4 GHz band on aircraft radar altimeters which generally operate in the 4.2-4.4 GHz band.
In the US, 5G will be rolled out on the 3.7-3.8 GHz band.
In India, the government is planning to roll out 5G in the 3.2-3.6 GHz band, perilously close to the danger mark that is currently being examined in the US.
The RTCA report issues dire warnings that even in the most fundamental scenarios, 5G radio frequencies could cause “exceptionally severe consequences to aircraft operations and aviation safety” in commercial planes.
The impact on shorter-haul regional aircraft, business jets and helicopters that fly at a lower altitude than commercial aircraft would be far greater especially when they fly over populated areas within range of a 5G base station.
RTCA noted, “This risk is widespread and has the potential for broad impacts to aviation operations in the United States, including the possibility of catastrophic failures leading to multiple fatalities.”
In low visibility landings, the kind of RISKS witnessed in many north Indian cities during the winter fog weeks and the rest of India in heavy monsoons, the impact could be even more devastating.
This, according to RTCA, would be the result of four kinds of failure caused by 5G interference.
First, 5G interference during an aircraft’s descent or take off could shut down both radar altimeters.
This would automatically disengage the auto-landing option leaving the pilots with little time to plan either an abortion or a go-around without knowing their distance from the ground.
If the pilots are unable to land the aircraft after repeated go-arounds, the air traffic control may have to shut off operations at the runway and possibly the airport.
Secondly, one of the two radar altimeters may switch off while the other may display wrong readings of the plane’s distance from the ground below due to 5G interference.
In this case, if the pilots rely on the sole functioning device and decide to land on those readings manually, it may lead to a “hard landing, and at worst, a catastrophic impact with the ground.”
Thirdly, both altimeters may show wrong readings which are different from each other.
In this case, the autopilot may use the wrong readings and crash the plane.
The autopilot may also sense an anomaly leading to pilot intervention which may or may not be timely to avert a disaster.
A similar accident is reported to have occurred with a Turkish Airlines flight at Amsterdam airport in 2009.
Lastly, both instruments may display wrong but similar readings due to 5G interference.
In this case neither the autopilot nor the pilots would be aware that they are headed for disaster.
The report states, “The approach will proceed with incorrect altitude readings causing either direct catastrophic impact with the ground, or causing the aircraft to stall and subsequently have a catastrophic impact with the ground.
"In this instance, the pilots will be unaware of the erroneous data and unable to intervene.
"The occurrence of such failures is certain to cause confusion among the flight crew which could further complicate and delay their response.”
In the Indian case, the band that will be up for sale is between 3.2-3.6 GHz which many believe should be an adequate leeway to prevent jeopardising aircraft operations.
An industry insider said, ”You have a guard band of around 300 MHz (difference between 3.6 GHz and the danger 3.9 GHz mark under review in the US) which is substantial as compared to some other nations.
"In any case 50 per cent of the spectrum is being deliberately kept out of reach of telecom operators by the government.
"So, the 5G roll out in India would be among the weakest in the world.
"This could prevent any air disasters due to interference.”
Would this mean Indians would be paying more for one of the slowest 5G networks in the world?
The industry expert said, “With the band, huge number of users and only half the spectrum available, India’s 5G certainly wouldn’t be the fastest.
"But that shouldn’t make a difference.
"Indians are used to living a life of constraints and seem to be happy with whatever they are being sold.”
There are a handful of nations in the world that are offering 5G spectrum upto the 3.7 GHz band.
They include the US, Italy, Switzerland, UK, Spain and Finland.
Nations like China and Hong Kong which have had functional 5G for a couple of years now have tried to circumvent the problem by offering bandwidth in the 4.8 GHz to 5 GHz band which is beyond the 4.2-4.4 GHz used by radars of commercial aircraft.
China has also limited the lower end of the spectrum to 3.6 GHz.
France was reportedly the other nation apart from the US which had conducted a study on the impact of 5G radio wave interference on aircraft safety.
Like the US, it had found that any interference could have deadly consequences for both the aircraft passengers and people on the ground.
The FAA has asked aircraft and radar altimeter manufacturers to continuously share information about their altitude reading equipment and results of their observations on interference of 5G radio waves.
Moreover, it has issued directions to airline operators to ensure that all 5G devices in checked in baggage are turned off and ‘protected from accidental activation.’
Meanwhile pilots have now been asked to instruct passengers to switch off their 5G devices while on the plane in a bid to lend some seriousness to the warning.
This job was earlier done by airhostesses whose warnings are usually ignored either due to ‘apathy or inattentiveness’ of the passenger.
Photograph: Rafael Marchante/Reuters