A single digit error caused a 4,000-mile detour.

By Cailey Rizzo
Updated: October 25, 2016
Pascal Pavani/Getty Images

Safety officials revealed Wednesday that it was pilot error that caused a plane to land nearly 4,000 miles from its original destination last year.

The pilot of an AirAsia X flight from Sydney to Malaysia incorrectly entered the plane’s longitude right before takeoff on March 10, 2015. The error caused the plane’s navigation system, flight guidance, GPS and flight control systems to go haywire, according to a report by the Australian Transport Safety Bureau.

The pilot inadvertently left out a zero when inputting the plane’s longitude, which made the plane’s navigation system believe that it was taking off from Cape Town, South Africa—almost 7,000 miles away. The A330 was not outfitted with “an upgraded flight management system that would have prevented the data entry error,” the ATSB’s report said.

The error was not detected until the plane was already airborne and heading in the wrong direction. Attempts to troubleshoot the problem just made matters worse. The autopilot and navigation systems were botched. The flight could not return to Sydney because of low clouds, rain and low visibility.

With radar guidance from air traffic controllers, the captain—who had logged over 22,000 miles—manually flew the plane to Melbourne. After three hours on the ground and lots of inspections, there was deemed to be no error with the onboard systems and the flight continued on to Kuala Lumpur with no problems.

This “position initialisation” error occurs about twice a year, the report said. In 2013, Airbus recommended its customers update their planes’ systems to prevent this type of error. However, three years after the recommendation, only about 46% of the world’s 515 affected planes have updated.

Since the incident, AirAsia X has updated its training procedures, emphasizing the importance of data entry.

“This occurrence highlights that even experienced flight crew are not immune from data entry errors,” the report said.

Cailey Rizzo writes about travel, art and culture and is the founding editor of The Local Dive. You can follow her on Instagram and Twitter @misscaileyanne.