The Aeronautical Telecommunication Network (ATN) comprises application entities and communication services which allow ground, air-to-ground and avionics data sub networks to interoperate. This is done by adopting common interface services and protocols based on International Standards. ATN is designed with four major elements. The first element is the ability to transfer data to an aircraft without sender knowledge of the aircraft location (network mobility). The second major element is the ability to simultaneously use the multiple air/ground links that are installed in an aircraft. This requires applications to specify cost, link, or speed preferences, which are used by the ATN when forwarding data. The third element is the ability to account for the low bandwidth air/ground data links available today and in the near future. Low bandwidth air/ground links require the use of data compression. The fourth element is the standardization of the services required by ATS applications (i.e., transport, session, presentation, and application functions) and the applications themselves, so that they are the same worldwide.