The solution to a complex engineering problem, as defined by ECSA is that the solution has one or more of the characteristics:       

• Involve wide-ranging and/or conflicting technical, non-technical issues (such as ethical, sustainability, legal, political, economic, societal) and consideration of future requirements.
• Have no obvious solution and require abstract thinking, creativity and originality in analysis to formulate suitable models.
• Involve infrequently encountered issues or novel problems.
• Address problems not encompassed by standards and codes of practice for professional engineering.
• Involve collaboration across engineering disciplines, other fields, and/or diverse groups of stakeholders with widely varying needs.
• Address high-level problems with many components or sub-problems that may require a systems approach.