Kathmandu, January 23

The country’s sole international airport has failed to operate its primary frequency for air traffic control for more than two weeks raising serious safety risk in Nepali airspace, it has been revealed.

“Two weeks have already passed since the primary frequency for aerodrome control service (118.1 MHz) at the control tower went dysfunctional owing to unknown interference and as a result critical ATC communications are being carried on the backup secondary frequency (118.5 MHz), which for the last few days is also not immune to the problem,” a senior ATC officer told this daily.

The situation could get worse and even lead to near-misses or even mid-air collision while handling inbound and outbound aircraft if the technical hitches are not resolved at the earliest, he added.

The Civil Aviation Authority of Nepal as an ATC provider is required to maintain both primary and secondary frequencies to ensure smooth flight operations as per international standard so that the users, including flight crew, can immediately tune their communication radios to the other if one is disturbed to maintain essential safety related communications.

“Multiple instances of interference have been recorded in the tower frequency (118.1 MHz) while communicating with aircraft pilots while the technical problems in the area control frequency have resulted in the suspension of Kathmandu-Mahendranagar-Delhi airway (L626), the shortest as well as major exit route for international carriers from Nepali airspace, for several days in the last two weeks.”

A senior captain with Nepal Airlines who often used the shortest L626 route also confirmed that pilots held communication with the ATC tower using secondary frequency for more than two weeks. “When we try to use 118.1 MHz to contact pilots, we hear Kantipur FM broadcast garbling critical aeronautical communications,” another tower ATC officer shared.

Though the stakeholders solely blame carelessness on the part of CAAN for its failure to adequately maintain the air traffic control system time and again, Devananda Upadhyaya, general manager at TIA, however, claimed that technicians have been monitoring the situation and trying to fix the problem. Ministry of Culture, Tourism and Civil Aviation has also received a written memo from CAAN about the frequency interference, a ministry official said.

According to TIA sources, the affected communication system developed by the Aeronautical Radio of Thailand (AeroThai), was recently upgraded under the controversial Asian Development Bank-funded Air Transport Capacity Enhancement Project (International Competitive Bidding -02) Project and has remained prone to problems resulting in poor availability and reliability against International Civil Aviation Organisation requirements.

GM Upadhyaya also said that outgoing air route (L626) was suspended for a few days to complete maintenance work at Nepalgunj repeater tower station.