Kathmandu, February 4

The country’s sole international airport has failed to operate its voice communications control system more than a month after it went dysfunctional, endangering flight safety.

“It’s been more than a month since the critical ATC communications are being carried out through backup portable VHF radio transceivers at Tribhuvan International Airport as the primary as well as secondary frequencies (118.1/118.5 MHz) for aerodrome control service at the control tower went dysfunctional due to VCCS failure,” on-duty air traffic controllers told this daily.

Interestingly, the technicians have also failed to identify the hitches that plague the communication system, according to a TIA source.

The situation could get worse and even lead to near-misses or even mid-air collision while handling inbound and outbound aircraft if the problem is not resolved, a senior ATC officer warned.

“Portable VHF radio transceivers can only be used as an emergency backup just for a day or two but VCCS witnessed a problem since December 16.”

According to him, poor-quality aging portable radio transceivers are also not immune from the problem as ATCs often receive complaints from the aircraft crew. “Neither the TIA authority nor the Civil Aviation Authority of Nepal seemed serious about resolving the problem.”

Strangely, the TIA management deliberately misled and chose not to warn the users while VCCS was idle for over a month, thus endangering flight safety.  “Till date, there is no Notice to Airmen issued to inform the users — flight crew — about the dysfunctional state of its primary and secondary frequencies,” a senior captain with a private airlines said, adding, “It’s a criminal negligence.”

The CAAN as an ATC provider is required to maintain both primary and secondary frequencies tuned under the VCCS to ensure smooth flight operations as per international standards so that the users can immediately tune their communication radios to the other if one is disturbed.

The International Civil Aviation Organisation requires extremely reliable equipment to prevent aircraft collision and ensure optimum utilisation of air space.

Admitting the VCCS failure for long, CAAN’s Deputy Director General Raj Kumar Chhetri, who took charge as TIA’s general manager just a couple of days ago, said that he would seriously take up the case and instruct the concerned departments to resolve the problem immediately.

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

As per the ICAO stipulations, air-ground communication facilities should enable direct, rapid, continuous and static-free two-way communications to take place between an aerodrome control tower and appropriately equipped aircraft operating at any distance within 25 nautical mile (45 km) of the aerodrome concerned,. “But, the portable VHF sets now cover just less than 5NM at TIA,” the ATC officer shared.