States have a responsibility, under the Chicago Convention, to ensure that acceptable levels of safety are established and maintained. States are further required to ensure that Safety Management Systems (SMS) are implemented by the providers of Air Traffic Services (ATS), which include the monitoring of overall safety levels.
At both national and organisational levels, therefore, Standards and Recommended Practices (SARPs) established by the International Civil Aviation Organisation (ICAO) require the regular monitoring and assessment of safety levels in air traffic management (ATM).