Phub Dem

The recent development concerning the launch of 5G in a 3.7–3.98 GHz band in the United States has led to immediate concern regarding the potential harmful interference to radio altimeters used in civil and commercial aircraft.

The U.S. Federal Aviation Administration (FAA) has warned that the new 5G technology could interfere with instruments such as altimeters, which measures how far above the ground an airplane is travelling.

Altimeter readouts are also used to facilitate automated landings and help detect dangerous wind shear currents.

Altimeters operate in the 4.2-4.4 GHz range, and the concern is that the auctioned frequencies sit too close to this range.




According to international media, the deployment of 5G has led to flight cancellation and delays in the United States due to the potential interfering concerns from the deployment of 5G in the vicinity of airports

However, in Bhutan, no risk of unsafe interference has been identified, according to Bhutan Civil Aviation Authority (BCAA).

According to the impact report, two telecom operators in Bhutan are assigned with the mid-band frequency of (3.4 – 3.6) GHz for deploying 5G services in Bhutan.

The authority did not receive any report of incidents or interference to aircraft instruments since the launch of 5G.

Beginning the launch of 5G services in December last year until February 25, Drukair, Bhutan Airlines, and Royal Bhutan Helicopter Service Limited carried out 196 operations (takeoff and landings).

The authority also confirmed the impact assessment during the virtual meeting among chief pilots, training managers, technical pilots and head of operations representatives from the three air operators.

The report states that the radio altimeter of RBHSL’s helicopter has been flying over almost all the 5G towers in Paro and Thimphu as close as 30 feet above live towers but haven’t experienced any issues. “RBHSL reconfirmed that they have no reservation and safety concern for helicopter operations due to 5G rollout by two telecom operators.”

Although Drukair and Bhutan Airlines have not encountered any issues during their operation in and out of Paro airport, the technical representatives from operators suggested restricting the installation of 5G towers along the arrival and departure route until a proper risk assessment, and the global consensus is reached.

The operators mentioned that the pilots are trained to overcome all kinds of system failures for the safe operation of flights as per the Standard Operating Procedures (SOP) provided by aircraft manufacturers.

Assessing the situation, BCAA issued an advisory circular to the operators regarding potential risk and safety measures in time of interference from 5G ground stations.

According to the Communication, Navigation and Surveillance (CNS) officer of BCAA, Karma Gayley, the authority asked the operators to conduct a safety risk assessment that includes training flight crews to deal with unreliable radio altimeter scenarios during landing and takeoff of recurrent flight training sessions conducted in the flight simulation training device. He said that such measures prepare air operators to deal with interference to radio altimeters from 5G operation.

He said that BCAA and BICMA would coordinate possible mitigation measures due to the operation of 5G stations and the installation of additional 5G stations around the vicinity of the airports and along the departure and arrival flight paths.




He said that BICMA would carry out regular frequency monitoring to prevent out-of-band frequency transmission from the mobile Base Transceiver Station (BTS) and power level monitoring of the 5G base station to ensure it is within the permissible level. “The telecom operators are not allowed to transmit and receive beyond the assigned range of frequencies, which means, the 5G mobile stations are not allowed to transmit and receive beyond 3.4 – 3.6GHz.”

Karma Gayley said that BICMA notified the telecom operators that the 5G base stations in the vicinity of the airports have to be relocated or shut down if any serious interference to aviation radios is experienced.

He said that while no event of 5G technology interfering with aircraft radio altimeters has been recorded, the concerned agencies are constantly monitoring the global updates on this matter.