Similarity in call signs with Tashi Air’s Bhutan Airlines may confuse … but not all pilots agree

Aviation: The national airline, Drukair, has raised issues of safety with the government concerning  the similarity of the call sign being used by Bhutan Airlines, a subsidiary of Tashi Air pvt ltd.

A call sign is used to identify and give instructions to a specific aircraft during radio communications between the aircraft and an air traffic control (ATC) tower during flight operations, mostly during takeoffs or landings.

Drukair’s call sign is Royal Bhutan, while Bhutan Airlines’ is Bhutan Air.  The call sign is followed by the number of the particular flight, for example, Royal Bhutan 129 or Bhutan Air 701.

Drukair CEO Tandin Jamso said the similarity in the call signs, as both include “Bhutan”, could lead to an incident.  He explained that this is because both airlines operate on the same sector, the Paro-Bangkok-Paro route, separated by only about 20-30 minutes.

The CEO said the similar call signs could get either the Bangkok ATC or airline pilots confused.  He explained that the radio frequency or channel with which an ATC communicates with aircraft is open, meaning all aircraft within a certain vicinity can listen in.

He said this raises the possibility of, for instance, a Drukair pilot following an instruction to descend to a certain altitude that may have been issued for a Bhutan Airlines flight, instead or vice versa.

“My biggest worry on the safety factor is on this one,” Tandin Jamso said.  He added that there would be no concern if there was significant time difference between the flights, or if the flights were operating in different directions or difference sectors.

Kuensel confirmed that there can be even less time separation between the flights.

For instance, today, a Bhutan Airlines (Bhutan Air 700) and Drukair flight (Royal Bhutan 128) arrive at 4:15pm and 4:30pm respectively.

Tandin Jamso said Drukair has communicated its concerns to the information and communications ministry. “MoIC should seriously view before anything happens,” he said, adding that ensuring safety is Drukair’s top priority.

Department of Civil Aviation (DCA) director Wangdi Gyaltshen said the Drukair management had communicated its concerns.  He said a meeting between the ministry, the department, and the two airlines had also been held and that DCA is studying the issue.

An observer in the aviation industry, requesting anonymity, said that there are hundreds of Thai Airways International flights that operate in and out of  Bangkok daily and that all these aircraft have “Thai” as their call sign. The observer said that if there is no safety concern about the similarity with “Thai” as a call sign, then there should not be one between Drukair and Bhutan Airlines.

The observer added that if there was a safety concern then the pilots or Bangkok ATC would have raised the issue. It was also pointed out that if the similarity in call signs was a safety concern the International Civil Aviation Organisation would not have approved the call sign.

A former captain with Drukair and former CEO of Tashi Air, David Young, said the call signs of the two airlines are not likely to be confused.  He explained this is because pilots usually pick up only the second half of the call sign.

David Young said that, as flight operations manager with Drukair in the 90s, he had changed the call sign of Drukair, which was then “Druk Air”, to Royal Bhutan, as it was too similar to Singapore based Silk Air.

“We’re half listening for messages sent to our call sign and often pick up only on the second part of the words, so that the ‘k’ at the end of Druk Air was sometimes confused between Silk Air and Druk Air,” he said.

“Royal Bhutan and Bhutan Air seem to me to be totally different,” he said, adding that pilots have to be alert for their own call sign, and if there is any confusion, should ask for confirmation from ATC. “I’m sure that the pilots of Drukair and Bhutan Airlines, being well trained professionals, are fully aware of this.”

An experienced pilot, who requested anonymity, also said there was no ground for concern.  The pilot said there was also a “squawk” or transponder code, which ATC uses to identify aircraft.  The pilot said the call signs were different enough to be not mistaken and added that, while there were “slips of the tongue” by Bangkok ATC, it was not considered a threat.

However, one experienced pilot, also requesting anonymity, said there was a risk of call signs being mistaken. “It was very wrong and strange of DCA to approve this right from the beginning,” the pilot said.

Tandin Jamso said Drukair has also objected to Tashi Air pvt ltd using “Bhutan Airlines” as its airline’s name.  He said this was because it has been creating confusion among passengers, as check-in counters usually open at the same time.  He added it has been observed that Drukair passengers have ended up at the Bhutan Airlines counters in Bangkok resulting in delays.

He suggested that the private airline should stick to Tashi Air, and to indicate that it was a Bhutanese airline below the title.

By Gyalsten K Dorji