Division (a) In order to provide air traffic control service, an air traffic control unit shall:

be provided with information on the intended movement of each aircraft, or variations therefrom, and with current information on the actual progress of each aircraft;

determine from the information received, the relative positions of known aircraft to each other;

issue clearances and information for the purpose of preventing collision between aircraft under its control and of expediting and maintaining an orderly flow of traffic;

coordinate clearances as necessary with other units:

1. (i)

   whenever an aircraft might otherwise conflict with traffic operated under the control of such other units;

2. (ii)

   before transferring control of an aircraft to such other units.