What happened
On 7 September 2019, an Etihad Airways Boeing 787-9, registration A6-BLF, was conducting a scheduled passenger flight from Abu Dhabi to Hong Kong International Airport. While performing an Instrument Landing System (ILS) approach to the then Runway 25R, the aircraft's autoflight system successfully intercepted the localizer at waypoint RIVER.
However, shortly after interception, the aircraft overshot the intended localizer course. The aircraft then drifted to the right, moving toward terrain to the north, and descended below the Minimum Sector Altitude (MSA) of 4,300 feet. During this deviation, the Enhanced Ground Proximity Warning System (EGPWS) did not trigger any alerts. The pilot flying recognized the deviation approximately 30 seconds later, disengaged the autoflight system, and took manual control. The crew successfully re-established the aircraft on the correct course roughly 11 nautical miles from the runway threshold and completed the landing without further incident. There were no injuries and no damage to the aircraft.
The investigation
The investigation examined the performance of the Autopilot Flight Director System (AFDS) and the flight control electronics. Investigators analyzed the flight data and the behavior of the aircraft's flight control module during the localizer capture phase. The inquiry involved cooperation from the UAE's Air Accident Investigation Sector, the US NTSB, the Hong Kong Civil Aviation Department, Boeing, and Etihad Airways.