Input error sends plane astray

AirAsia X flight from Sydney to KL ended up in Melbourne after pilot's mistake

MELBOURNE • An AirAsia X flight from Sydney to Kuala Lumpur ended up in Melbourne instead after the pilot entered the wrong coordinates into the internal navigation system, an investigation shows.

In a report released yesterday on the incident in March last year, the Australian Transport Safety Bureau (ATSB) described how the incorrect coordinates entry by the captain, a series of alarms and deteriorating weather in Sydney meant the plane had to fly to Melbourne, more than 700km away.

After departing Sydney following a series of alarms, the flight crew told traffic control they would try to restore the aircraft's navigation systems but could not. Instead, the captain and first officer relied on continuous radar vectors messages from traffic controllers to make it to Melbourne, where the system was reset.

The Airbus A330 had been scheduled to leave Sydney international airport at 11.55am on March 10 last year, and arrive in Kuala Lumpur just under nine hours later.

According to The Guardian newspaper, ordinarily the captain would conduct an external inspection of the plane while the first officer completed the position initialisation and alignment procedures.

But that day, the captain's ear protection was not available so he took over the cockpit tasks, which included entering the current coordinates, usually those of the departure gate, into the plane's internal navigation system.

The plane spent three hours on the ground in Melbourne fixing the problem before departing for Kuala Lumpur, where it arrived six hours behind schedule.

The captain manually copied the coordinates from a sign outside the cockpit window, and later analysis showed a "data entry error". Instead of entering the longitude as 151° 9.8' east, or 15109.8 in the system, he incorrectly entered it as 15° 19.8' east, or 01519.8.

"This resulted in a positional error in excess of 11,000km, which adversely affected the aircraft's navigation systems and some alerting systems," the ATSB said, adding this "equates to a position off the coast of Cape Town, South Africa, about 11,000km from Sydney airport".

The report said the crew had "a number of opportunities to identify and correct the error" but did not notice it until they had become airborne and started to track in the wrong direction.

Those opportunities included a flag or message that flashed up on the captain's screen during crosscheck of the cockpit preparations, which the first officer later told ATSB investigators he had seen but not mentioned because it was "too quick to interpret"; and three separate chimes which, because they were not accompanied by a message from the computer, were ignored, The Guardian reported.

The plane spent three hours on the ground in Melbourne fixing the problem before departing for Kuala Lumpur, where it arrived six hours behind schedule.

The ATSB said "even experienced flight crew are not immune from data entry errors", and advised AirAsia to upgrade its flight systems to assist in preventing or detecting such errors in future.

AirAsia X told The Straits Times it had cooperated fully with the Australian investigators.

The ATSB report said the airline had taken steps, including "the development of a training bulletin and package for its flight crews that emphasised the correct operation and alignment of the air data and inertial reference system".

A version of this article appeared in the print edition of The Straits Times on September 08, 2016, with the headline 'Input error sends plane astray'. Print Edition | Subscribe