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`Slip’ spins drama in the skies

Phila Siu  HK Standard

Wednesday, May 30, 2012

A “slip of the tongue” placed two passenger planes carrying about 600 people on a collision course in Hong Kong airspace two weeks ago, an investigation by The Standard reveals.

Instead of instructing an aircraft to descend to 36,000 feet, the controller ordered the pilot to drop to 26,000 feet, according to the Civil Aviation Department. But the error was rectified in time, just as the collision avoidance system of one of the planes was also activated.

A CAD spokeswoman said the May 14 incident involved a Hong Kong Airlines B737 bound for the SAR from Denpasar, Bali, and a Jeju Air B737 flying through Hong Kong to Bangkok from South Korea.

The controller, understood to be a non-local, intended to instruct the Hong Kong Airlines plane to drop to 36,000 feet but, due to a “slip of the tongue,” said 26,000 feet. The Jeju Air plane was at 34,000 feet at that time.

After noticing the Hong Kong Airlines plane was passing through 36,000 feet on its descent, the controller immediately corrected the situation. The plane then ascended to the correct level.

During the process, the traffic collision avoidance system on the Jeju Air plane was activated, moving it to a lower level.

The distance between the two aircraft was 4.6 kilometers horizontally and 700 feet vertically – against the standard safe horizontal distance of 9.25km and a vertical distance of 1,000 feet.

But the CAD spokeswoman stressed there was “no risk of collision.” She also ruled out fatigue as a reaso

n for the incident.

“The controller had been off duty for 14 hours and had just commenced duty when the minor incident occurred,” she said, adding the controller has been serving in the CAD for more than 13 years.

Former CAD chief Peter Lok Kung-nam said the two aircraft should have been within visual contact of each other.

“The danger was higher than usual but there wasn’t any immediate risk of collision as they were not flying toward each other,” Lok said.

This latest near-crash incident happened eight months after The Standard revealed that a Cathay Pacific plane and a Dragonair plane came within six seconds of a head-on collision, prompting the CAD to review its operation system.

A senior Dragonair pilot said yesterday the situation in the air traffic control tower “is only getting worse” since August, and that some of his fellow pilots are expecting an accident to happen soon.

The pilot said it is due to poor CAD management and the fact that many local controllers, instead of experienced foreign controllers, are hired.

However, Hong Kong Air Traffic Control Association chairman Ivan Chan Pui-kit said the situation has improved since August to what he calls a “satisfactory” level.

He also agreed the latest incident was merely a “slip of tongue.”

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