After nearly four decades, Kathmandu’s Tribhuvan International Airport, one of the most challenging airports to operate in the world, is set to get a new air traffic control tower equipped with modern systems and technology.

Nepal’s Cabinet this week approved a grant of around Rs2.73 billion from the government of Japan to construct a modern air traffic control (ATC) tower at the TIA. It is the fourth major grant from Japan aimed at enhancing the safety of Nepal’s civil aviation sector.

The proposed nine-storey tower will be built on the eastern side of the runway, near the airport’s rescue and firefighting division, according to sources familiar with the project.

On July 28, Dr Akihiko Tanaka toured the Japan International Cooperation Agency (JICA)-supported civil aviation safety facilities at the TIA and inspected the proposed site for the new ATC tower.

“As the existing ATC system is too old, we hope the new facility will help a lot to strengthen the air safety system, particularly for challenging airports like TIA,” said Nabin Prasad Acharya, deputy director at the Air Traffic Management Department of the Civil Aviation Authority of Nepal.

The project will involve construction of a new ATC tower and an air navigation service building, along with installation of an advanced air traffic management system, including a multi-sensor data processing system.

The existing control tower will remain in operation as a backup.

Officials say the new tower cannot be built higher than 32 metres because of Kathmandu’s bowl-shaped geography and the need to maintain safe flight paths around the airport.

Despite the height restriction, the proposed tower will provide a significantly more modern working environment and advanced surveillance and communication systems for air traffic controllers.

The latest grant is the largest assistance pledged by Japan for Nepal’s civil aviation sector.

“Japan has been supporting Nepal’s civil aviation sector for a long time. This is yet another gesture of goodwill,” said Acharya.

If preparations proceed as planned, a formal agreement for the three-year project could be signed by September, Acharya said. Japan plans to mobilise workers at the project site by October.

JICA and the Japanese government have supported the Civil Aviation Authority of Nepal in improving the safety and efficiency of air traffic management since 1988. Japan’s involvement gained particular importance following two major air disasters in Nepal in 1992.

On July 31, 1992, Thai Airways International Flight 311, flying from Bangkok to Kathmandu, crashed into a hill north of Kathmandu near Langtang National Park, killing all 113 people on board. The flight included 17 Japanese nationals.

Less than two months later, on September 28, Pakistan International Airlines Flight 268 crashed into a hillside south of Kathmandu, killing all 167 people on board. It remains the deadliest aviation disaster in Nepal’s history.

Before the twin disasters, Nepal operated in a non-radar environment. Air traffic control at TIA relied largely on procedural radio position reports from pilots rather than electronic surveillance. The crashes prompted Nepal to move towards modern radar-based air traffic management.

Nepal subsequently requested Japan’s assistance in installing the country’s first radar system.

In 1994, the Japanese government conducted a detailed study for installing a radar system at TIA, and the project was completed in 1997 under Japanese official development assistance at a cost of $34 million.

Again, in March 2013, JICA provided Rs906 million in grant assistance to install two advanced radars at TIA and Bhattedanda, on the southern rim of the Valley in Lalitpur.

The Monopulse Secondary Surveillance Radar at Bhattedanda has been providing en-route surveillance of flights within a range of up to 250 nautical miles, or about 450 km, since it began commercial operation on February 1, 2018.

The radar monitors Nepal’s airspace and tracks aircraft as far as Surkhet in the west and across the country to the east, north and south, extending from the northern mountain range to the Indian border. The system has made it easier for TIA air traffic controllers to monitor Nepal’s airspace more safely and efficiently.

In September 2016, Japan provided another grant of Rs1.51 billion to enhance the safety and efficiency of air transport in Nepal.

The assistance, then the largest Japanese grant to Nepal’s civil aviation sector, was used to implement the Project for Improvement of Aviation Safety Facilities. The project covered safety improvements at eight airports across Nepal, including five short take-off and landing (STOL) airstrips.

Beyond grant assistance and equipment installation, JICA has supported Nepal’s aviation sector by dispatching experts and senior volunteers and implementing technical cooperation projects. These have included establishing and operating a spare-parts management centre and building the capacity of personnel to operate and maintain aviation safety equipment.

The latest project comes as TIA continues to face growing pressure from rising passenger and aircraft movements.

TIA is the main hub of Nepal’s domestic airport network as well as the country’s principal international gateway.

In 2000, TIA handled 1.06 million international passengers. Over the past 25 years, international passenger traffic through Nepal’s primary aviation hub has increased roughly fivefold, crossing the 5 million mark.

In terms of flight movements, the airport handled 34,600 international takeoffs and landings in 2025, compared with 8,105 in 2000.

Domestic air travel has also expanded sharply. Nepal’s seven fixed-wing airlines and 12 helicopter companies carried 4.56 million passengers in 2025, the highest passenger traffic ever recorded by the country’s domestic aviation industry despite the economic slowdown.

The number of domestic air travellers has increased more than fourfold since 2000, when only 853,000 passengers flew domestically and air travel was widely considered a luxury.

Domestic flight movements have also nearly doubled, from 55,998 in 2000 to 103,556 in 2025.

With passenger numbers and aircraft movements continuing to rise, aviation officials say modernising the control tower and air traffic management system has become increasingly important to maintaining safety and improving the efficiency of Nepal’s airspace.