WGNO3-WP16
Prepared and presented by Kors van den Boogaard
On board ATN installation in conformance with the present ICAO SARPs is progressing in light of the Miami operations and the Link 2000+ programmes. However, there are increasingly signs that the “OSI-based
ATN protocols” will have a limited lifetime not only for ground-to-ground communication but also for air-to-ground communication. Therefore to stay abreast of the development, the feasibility of the transition towards industry based protocols for air to ground communications such as TCP/IP and VoIP needs to be assessed as early as possible.
Introduction
The long development time of the ATN OSI based protocols, the fast development in the telecommunication industry and the limited availability of ATN based data link services are the reason that some of the ATN-OSI layers are becoming a legacy protocol before global deployment on the ground and in the aircraft.
At present the airspace users don’t have any choice but to implement the OSI based ATN to support the Miami and Link 2000+ programmes. However on the ground the non-
ICAO standard TCP/IP protocol is introduced.
Working group N tasked with developing a recommendation for ICAO on the future of
ATN and more in particular to consider a transition to TCP/IP is invited to take note of the dilemma the airspace users are facing.
The dilemma
After a long time of development the airspace users have access to a certified ATN airborne router to support ICAO SARPs compliant Air Traffic Data link services. The relative high costs in relation to the very limited available current and planned ATN based data link service makes it difficult for airlines to justify the installation. Meanwhile various alternatives have been implemented based on identified need and cost justification.

WGNO3-WP16
At present the airlines are facing the dilemma to fully pursue the deployment of ATN-
OSI based protocols while not sure whether there will be a transition path to other protocols developed and under development in the industry. Alternatively, they have a choice to limit the deployment to ATS based data link programmes, which are intended to overcome anticipated gridlocks and improve service efficiency.
The transition.
For a successful implementation of a new set of protocols based on TCP/IP, a well defined transition path from the “legacy systems” needs to be defined taking into account the following considerations: a) The platforms from which a transition has to be defined: ACARS-AOA-FANS
1/A-ATN-TCP/IPv4 b) The timeliness of the of standards availability and the transition path to those standards c) Available industry standards and the ITU-T and IETF work on next generation network standards d) The introduction of security e) Certification requirements and process f) Data Link Programmes in progress g) Need to maintain existing applications h) Introduction of new applications: i.e. SWIM, CDM i) Introduction of new services: such as VoIP.
Recommendation:
WG-N is requested to a) Note the paper and b) Take account of the considerations in this paper for its work on transition to
TCP/IP.