An All Nippon Airways Boeing 787 lands at Hong Kong International Airport for the airplane's inaugural commercial flight from Japan, Oct 26, 2011. (PHOTO / AP)

HONG KONG – An investigation into four incidents involving Boeing 787 passenger aircraft which deviated from their courses while approaching the Hong Kong International Airport in 2019 found that a software issue in the Autopilot Flight Director System had caused the troubles.

In all four incidents that took place between July and October 2019, the aircraft deviated from the courses during Instrument Landing System approaches to landing. The pilots then assumed manual control of the aircraft and landed safely. 

None of the aircraft was damaged and no one was injured in the incidents, according to the Air Accident Investigation Authority (AAIA), which published the investigation reports on Friday.

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“The investigation team has made one safety recommendation and the aircraft manufacturer has taken relevant action,” the government said in a statement.

The investigators also identified an audio quality issue during a review of audio recording of a cockpit voice recorder in one of the incidents, it said. 

The investigation team has made one safety recommendation based on which the aircraft manufacturer is reviewing the necessary actions, added the statement.

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"The objective of the investigation was to identify the circumstances and causes of the incidents with a view to preventing a recurrence," said a spokesperson for AAIA, an independent investigation authority responsible for the investigation of civil aircraft accidents and serious incidents.