On 30 July 2011, a Virgin Australia Airlines, Embraer-Empresa Brasileira de Aeronáutica ERJ 190-100 IGW aircraft, registered VH-ZPA, was being operated on a scheduled passenger service from Sydney, New South Wales to Melbourne, Victoria.
The crew were assigned the LIZZI FIVE VICTOR standard arrival route for a visual approach to runway 34 at Melbourne by air traffic control, with a requirement to cross waypoint SHEED (overhead Essendon Airport) at or above 2,500 ft.
When about 3 NM before SHEED, the First Officer (FO) disconnected the autopilot as he believed he had visually identified SHEED (Essendon Airport) and passed overhead. Immediately after, the aircraft descended through 2,500 ft. The descent was continued with the aircraft actually crossing overhead SHEED at about 1,800 ft. Neither crew identified the error until receiving altitude alerts.
The operator conducted an investigation into the incident and identified that the crew's situation awareness had reduced, resulting in the aircraft being flown 700 ft below the required altitude restriction at SHEED.
This incident emphasises the impact reduced situation awareness can have, and the importance of monitoring not only the aircraft's state, but also the actions of other crew members.