Risk is a factor that exists in every human endeavour, including operations involving aircraft whether in the air or on the ground. Each aircraft movement involves some level of risk because the system, being human-based, is fallible. Identifying and mitigating risk is critical to increasing the safety levels. The Risk Analysis Tool methodology (RAT) provides a method for consistent and coherent identification of risk elements. It also allows users to effectively prioritise actions designed to reduce the effect of those elements. The RAT has evolved over time to be a sophisticated, yet simple, mechanism for quantifying the level of risk present in any ATM related incident. Requiring only a brief series of inputs to produce a valid result, the RAT expresses the relationship between actions and consequences and provides a quantifiable value to these relationships.