This requirement concerns the use of a quantitative risk based-approach in Air Traffic Management when introducing and/or planning changes to the ATM System1. This requirement covers the human, procedural and equipment (hardware, software) elements of the ATM System as well as its environment of operations. This requirement covers the complete life-cycle of the ATM System, and, in particular, of its constituent parts. This requirement does not address the assessment of introducing and/or planning organisational or management changes to the ATM service provision2.