The ICAO Secretariat is under the direct authority of the Secretary General. It consists of five bureaus: the Air Navigation Bureau (ANB), the Air Transport Bureau (ATB), the Technical Cooperation Bureau (TCB), the Legal Affairs and External Relations Bureau, and the Bureau of Administration and Services. IFATCA has interactions mainly with the ANB.
These five bureaus report directly to the Secretary General and each of them is supported by one or more Deputy Director. Depending on the bureau, there are also Chiefs for the different sections and a number of senior officers and technical officers.
The seven Regional Offices are also under the perview of the Secretary General and are supported by a Regional Director. To learn more about the Regional Offices, click here. The following chart describes the hierarchy in ICAO and the role of the Secretariat within the Organization:

The Air Navigation Bureau is itself divided into three different groups: monitoring and oversight, air navigation capacity and efficiency, and aviation safety. IFATCA interacts mainly with the air navigation capacity and efficiency part of the ANB, and more specifically with the Airspace Management and Optimization Section (AMO). The work of the ANB touches four different elements:
Policy and Standardization
Safety and Infrastructure Monitoring
Safety and Infrastructure Analysis
Safety and Infrastructure Implementation
