Operational non-compliance involving an Aero Commander 681, VH-NYE, 33 km south of Richmond, New South Wales, on 18 March 1993

The Aero Commander was cleared to descend to 5,000 ft, on track from Richmond to Bankstown. Shortly after, the pilot was instructed to contact Sydney Approach, who then gave him a radar vector to track south of Richmond direct to Westmead.

The controller subsequently observed the radar height display of the aircraft indicated 4,400 ft and informed the pilot that he had descended below his assigned altitude. After being instructed to maintain 4,000 ft the aircraft was processed normally to Bankstown. The pilot later reported that he descended below his assigned altitude when he misread his assigned altitude indicator, whilst changing frequency to Sydney Approach. He was also expecting a requirement to be at 2,000 ft by 22 DME Sydney, as he had experienced on previous approaches into Bankstown.