Mode awareness issue - VH-­NXN, near Ayers Rock Aerodrome, Northern Territory, on 14 July 2009

On 14 July 2009, at about 0948 Central Standard Time, the flight crew of a Boeing 717-200 aircraft, registered VH-NXN, were conducting a
visual approach to runway 13 at Ayers Rock, Northern Territory. While carrying out a practise circling approach, the pilot in command observed what he believed to be abnormal engine response.

While the flight crew addressed the apparent engine problem, the aircraft's airspeed reduced below the normal manoeuvring speed on two occasions. However, the aircraft landed without further incident and a subsequent analysis of recorded data indicated that safe control of the aircraft was maintained throughout.

In response to this incident, the operator issued a Notice to Pilots regarding autothrottle mode awareness and made a number of changes to the Boeing 717 operations manuals.

Those changes described a number of restrictions on the automation modes used during critical stages of flight that the operator believed were appropriate to prevent automation 'surprises'.