How did a commercial jet bound for Southeast Asia end up landing in Australia? Good old-fashioned human error.

You might remember hearing about Airbus A330, the Malaysia-bound AirAsia flight that touched down at Sydney's international airport instead of arriving at its intended destination, Kuala Lumpur, on March 10, 2015. Now, according to CNN, an aviation investigation report reveals that the plane’s pilot made a big blunder: He accidentally entered incorrect coordinates for plane's starting position into the flight's onboard navigation systems [PDF].

To be fair, as The Guardian points out, entering the plane’s coordinates isn’t typically part of the pilot’s job. The report states that his earmuffs were defective, so the captain and the first officer switched their normal pre-flight checks. The pilot, who typically inspects the plane externally, stayed inside the cockpit and performed the first officer’s duties. Among other tasks, they involved finalizing the plane’s current coordinates—which are normally the coordinates of the departure gate—into the plane’s internal navigation system before takeoff.

The captain looked out the cockpit window, and manually recorded coordinates from a sign into the system. However, he accidentally recorded the longitude wrong, resulting “in a positional error in excess of 11,000km, which adversely affected the aircraft’s navigation systems and some alerting systems,” the Australian Transit Safety Bureau (ATSB) wrote in their report.

Alarms, messages, and warnings popped up, but the plane’s crew ignored them. In fact, they didn’t even notice that things were amiss until the plane took off, and it started tracking in the wrong direction.

The captain and the first officer tried to fix their navigation, to no avail. They wanted to return to Sydney, but since the navigation systems were out of whack, they had to rely solely on visuals. The weather was bad in Sydney, so air traffic control advised them to head to Melbourne.

The plane spent three hours in Melbourne fixing the system, and later arrived in Kuala Lumpur six hours later than intended. To prevent future flight snafus, the ATSB later recommended that AirAsia upgrade its flight systems. The airline followed suit, and also sent staffers additional training materials and briefed them on the investigation's findings.

[h/t CNN]

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