Civil Air Navigation Services Organisation (CANSO)
CANSO is the global voice of the companies that provide air traffic control (air navigation service providers – ANSPs). CANSO was established in 1998  and represents the interests of air navigation service providers (ANSPs) worldwide.

Call sign
Call signs are used to clearly identify aircraft.

Continuous descent operations (CDO)
Continuous descent operations are conducted by arriving aircraft to reduce their noise impact. Performing continuous descent operations means that aircraft –  from a specified altitude on – use a low power setting and glide smoothly towards the runway. The optimal starting point would be cruising level, as a long descent offers most benefits. However, this variant is extremely difficult to implement in practice as such a descent would lead the aircraft through several flight levels that may be assigned to other aircraft. This would involve an enormous coordination effort, since the descent has to be continuous, i.e. uninterrupted.

A clearance, or an air traffic control clearance, is the authorisation for an aircraft to proceed under conditions specified by an air traffic control unit, such as clearance for take-off, a certain arrival or departure route, change of heading, altitude or speed.