Aviation: The Department of Civil Aviation (DCA) has found no cause for concern regarding similarity in radio call signs between Drukair and Tashi Air subsidiary Bhutan Airlines.

A radio call sign is assigned to a specific aircraft and used by an Air Traffic Control (ATC) tower to give instructions to that aircraft using radio communications, such as whether to lower or increase altitude.

The national airline had raised safety concerns that the call signs of the two airlines, “Royal Bhutan” for Drukair and “Bhutan Air” for Bhutan Airlines was too similar and could lead to an incident.

The radio call sign is also followed by the flight number. For instance, today, a Royal Bhutan 120 and a Bhutan Air 700 will operate to Bangkok.

The national airline reasoned that with both airlines operating on the Paro-Bangkok sector with as little as 15 minutes for some flights, either ATC or the pilots may err given that both audio call signs include “Bhutan” and that ATC could issue or pilots could follow instructions meant for the other aircraft.

DCA director Wangdi Gyaltshen said that the department has studied the issue and obtained feedback from other countries and pilots but has found no cause for concern.

“They’ve all the reason to believe there is no issue,” he said.

The director said that it was also pointed out that in airports like Suvarnabhumi in Bangkok there are large numbers of aircraft of the same airline that operate close to each other, all with the same radio call sign. For instance, Thai Airways International operates with the radio call sign Thai and there are usually a few of the airline’s aircraft operating around the same time around Savarnabhumi.

Observers in the aviation industry also pointed out that at times Drukair also operates two flights close to each other to Bangkok, which would both be called Royal Bhutan and only distinguishable by the flight number.

However, director Wangdi Gyaltshen said that even though the department has found no cause for concern, ultimately flight safety still depends on the pilots and ATC. He said that both sides must ensure that communications between each other are understood clearly and precisely and that all standard communications procedures are followed.

By Gyalsten K Dorji