The CNS/ATM (Communication, Navigation and Surveillance/Air Traffic Management) concept, adopted by the International Civil Aviation Organisation (ICAO), envisages the use of datalink communications, satellite navigation systems and Automatic Dependent Surveillance (ADS) in the future provision of ATM. Today, a range of dissimilar CNS systems supports pilots and controllers in different phases of flight. The emergence of datalink services creates an opportunity to establish integrated, seamless gate-to-gate services, i.e. from the departure gate to docking at the arrival gate.

Work on international standardisation is ongoing for the Self-Organising Time Division Multiple Access (STDMA) technology, which has been developed to meet the requirements for a high-capacity datalink to support CNS systems. ICAO has adopted VDL (VHF Digital Link) Mode 4 as the designation for the STDMA technology when standardised for civil aviation.