ABSTRACT: The 51^st Air Traffic Control Association Annual Conference and Exposition marks a new direction and challenge for the art and science of Air Traffic Control (ATC), most notably, the advancement of the Next Generation Air Transportation System (NGATS). In the emerging era of NGATS, the opportunity exists to transform the existing ATC system from an industrial-age, ground-based architecture to an information-age, automated airborne-centric ATC management system.

The majority of Aviation Command and Control (C2) systems rely on complex communications to relay information within a terminal area, but do not always lend themselves to transporting this information to remote users. One of the goals of this paper is to examine some existing and emerging standards that can be applied to distribute vital information to remote users. In this evolving era of Information Age Transformation, major advancements in sensors and communications are being driven by innovative and novel Web-based technical approaches, ostensibly through Service Oriented Architecture (SOA) design principles. Another goal of this paper is to highlight the benefits of using these standards to provide situational awareness and federated data displays through the use of SOA approaches. SOA is about self-descriptive eXtensible Mark-up Language (XML) data services that are discoverable and consumable. This paper will focus on two approaches: an architectural design pattern referred to as REpresentational State Transfer (REST), and another based on what is commonly referred to as a Web Services or WS* technology stack.

The REST approach uses Really Simple Syndication (RSS) and derivatives such as atom, Resource Description Framework (RDF), or even Plain Old XML (POX) to provide stateless access to data objects over the Web. This is one mechanism for stateless Xml-based notification, generally viewed as a simple RESTful or REST style approach to an SOA. It is important to note that RSS data transactions are stateless. Another approach provides stateful XML-based notification by piggy-backing on eXtensible Messaging and Presence Protocol (XMPP) as the XML transport. XMPP provides a better alternative for near real-time exchanges of XML data. An example of this application is a remote display that shows a radar picture of a terminal area, along with changing wind-speed and direction conditions. An alternative stateful approach uses Session Initiation Protocol (SIP) as the XML transport. It comes down to whether or not the solution requires a stateless or stateful connection.

The WS* approach is also being used in web services, web clients and internet-friendly communications devices to remotely view ATC data. An example of this is the Navy’s Remote Observer Display, which provides weather forecasters and pilots with 1-minute up-to-date Automated Surface Observing System information to inform pilots of take-off and landing conditions during pre-flight forecasts and briefings.

As more services become available, additional data overlays can be integrated into web clients to provide consumers with all types of data and information in a common operational picture using a single, tailorable client.

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