Since pilot error accounts for between one-third and 60% of aviation accidents, advances in automation and technology could replace some or all of the duties of the aircraft pilots. Automation since the 1980s has already eliminated the need for flight engineers. In complex situations with severely degraded systems, the problem-solving and judgement capability of humans is challenging to achieve with automated systems, for example the catastrophic engine failures experienced by United Airlines Flight 232 and Qantas Flight 32. However, with more accurate software modeling of aeronautic factors, test planes have been successfully flown in these conditions.