Aeronautical mobile communications panel(amcp) Working Group n networking

This Information paper discusses the background, development, and implementation of the Aeronautical Information System Replacement (AIS-R) using TCP/IP to communicate with various military and FAA facilities.

The FAA has a continuing mission need for electronic exchange of flight planning information with the military and general aviation communities. AIS-R provides an automated means for flight plan delivery, distribution of weather products and also flight planning data to general aviation users and various National Airspace System subsystems. It also provides the required interfaces, Internet Protocols conversions, and databases needed for the flight planning process. AIS-R is a server-based application that communicates using Transmission Control Protocol/Internet Protocols (TCP/IP) and could possibly support international users through public networks.

The Members of the Meeting are invited to consider the information presented in this paper.

The Aeronautical Information System Replacement (AIS-R) is a web-based server application that will be used by the general aviation and military communities to obtain and distribute aeronautical information such as Notice to Airmen (NOTAM), Pilot Reports (PIREP) and weather products. AIS-R will provide aeronautical information services to the FAA Air Traffic Control facilities such as the 20 Air Route Traffic Control Center (ARTCC) facilities, the San Juan Combined Center Radar Approach Control (CERAP) facility, seven Regional Operations Centers (ROC), the William J. Hughes Technical Center (WJHTC), and the FAA Aeronautical Center. AIS-R also provides services to the Miami and New York Automated International Flight Service Station (AIFSS) facilities and the other 55 Automated Flight Service Station (AFSS) locations for a backup capability to the Model One Full Capacity (M1FC) system.

Military base operations (MBO) access the AIS-R only for flight plan processing. More than 195 Department of Defense (DoD) MBO facilities are currently using the AIS-R services through the Defense Information Services Agency (DISA) Unclassified but Sensitive (N) Internet Protocol (IP) Router Network (NIPRNet).

The AIS-R vendor is responsible for the development and maintenance of the web-based application These responsibilities encompass the design, hardware and software integration, implementation, daily operation and maintenance, help desk service, and training support as directed. Primary AIS-R servers are physically located in Herndon, VA, however efforts are underway to establish a geographically diverse backup at the National Network Control Center (NNCC) in Salt Lake City, UT. In conjunction with the Defense Internet NOTAM Service (DINS) and the United States NOTAM Service (USNS), AIS-R will be one of a number of web-based client/server systems currently being provided to the FAA and military users.

AIS-R provides an automated means of collection and distribution of Weather (Service A messages) and Flight Plan Data, NOTAM messages, PIREPs, and other operational information (Service B messages) to various National Airspace System (NAS) and military users and subsystems. Further definition and functions of the AIS-R Service A and Service B messages are:

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  Service A–Weather
  

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  Ingest, store, and manage required weather data from the Weather Message Switching Center Replacement (WMSCR)
  
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  Accept weather observations and forward them to the WMSCR
  
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  Provide requested weather data to users by location identifier and collectives
  

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  Service B–Flight Operations
  

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  Process flight plans from initial receipt to transmission to the NAS, including military
  
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  Provide flight plan filing, amendment, and cancellation capabilities to the user
  
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  NOTAM retrieval based on validated routes
  
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  Deliver roger/reject messages to the correct user
  
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  Maintain messages destined for users not logged in for future delivery.
  

A
IS-R system access for the FAA operational sites will be through several IP-based networks as shown in Figure 1. Connectivity to the AIS-R servers at larger FAA facilities will be through dedicated high-speed FAA Wide Area Network (WAN) connections. Regional Offices, AFSS facilities, and selected other sites will use either dedicated circuits to the larger FAA facilities or the public networks to access the servers. The security architecture includes the use of Secure Socket Layer (SSL) with Public Key Infrastructure (PKI). Certificates are issued in order to authenticate each AIS user.

AIS-R users in the larger FAA facilities such as ARTCC and AFSS sites will access the servers through the FAA Internet Protocol Multi-user Network (FIRMNET). FIRMNET is an IP-routed WAN initially implemented primarily on the Bandwidth Manager platform network. The AIS-R IP packets are routed over the circuit switched virtual connections, using the FAA-owned and leased circuits for transmission.

AIS-R is also required to interface with the NADIN Packet Switching Network (PSN) in order to provide flight planning information to the NADIN Message Switching Network (MSN). The collection and distribution of weather information, flight plan data, and advisories is accomplished through dedicated connectivity between the two AIS-R server locations and the NADIN PSN nodes. Service A and Service B messages along with weather data is collected from and distribute to the other sites through the NADIN PSN network. Requests for information from the AIS-R sites to the servers are distributed through this interface.

Both the NADIN PSN and MSN are International Telecommunications Union (ITU) X.25 protocol-based networks. NADIN MSN is accessed to interface with the Host Computer System (HCS) for filing flight plans and receiving confirmations. Currently, there are three NADIN PSN X.121 addresses allocated to each AIS-R server site. These X.121 addresses are used to transport flight plan data between the AIS-R user workstations and the NADIN MSN switch. To accommodate all the AIS-R users, sub-addressing is used to expand the X.121 address by adding the thirteenth and fourteenth digit. These extra two digits allow 99 additional users to access NADIN. NADIN MSN uses four digit station numbers to map the AIS-R workstation unique eight-character AFTN and ICAO identifier to the specific X.121 sub-address and then direct the message to the correct workstation. X.25 translation to/from IP occurs in the front-end routers at each server site. The AIS-R servers will have separate X.121 addresses for each of the NADIN PSN access circuits. The AIS-R server will address the Salt Lake City NADIN MSN for flights originating in the western portion of the United States while the Atlanta NADIN MSN will be addressed for flights originating in the eastern portion.

Weather and flight information is currently collected and/or distributed by the primary server using a combination of traditional database web-based applications and web server/browser applications. The AIS-R server systems access the National Flight Data Center (NFDC) data and periodic user configuration files. Connectivity between the primary and secondary server sites is through a T1 circuit. The AIS-R is currently capable of supporting at least 600 users simultaneously while meeting all functional and performance requirements.

The cutover process is divided into two phases. One for the military users and one for the FAA users. To limit the number of NADIN MSN system software modifications required to complete the transition process, each phase is designed to accommodate as many users as possible.

The cutover of military users to the AIS-R system in the first phase has been completed. The process began with establishing dual-distribution of NADIN messages to both AIS and AIS-R for all MBO sites. As users began to cutover to AIS-R, NADIN message traffic to the current AIS was discarded. At the start of this phase, there were an initial trial group of MBO sites that began using AIS-R for test purposes. This test group was to ensure that the system was working as intended. Following that initial trial period, the remaining MBO sites were transition to AIS-R. Dual-distribution of military NADIN message data has been discontinued except for a few sites. These MBO sites will be continued under dual-distribution of NADIN messages until they are transitioned. These sites will be completed by the end of June 2003.

The second phase will commence when AIS-R is ready to support the FAA ARTCC, AFSS and ROC facilities. Similar to the military cutover, the transition of FAA sites will commence with the dual-distribution of NADIN message traffic for all FAA sites being sent to AIS and AIS-R. A phased transition will be followed with the ROC facilities being the first sites to be transitioned. Then the AFSS facilities will be transitioned in reverse order of the replacement to the M1FC implementation schedule followed by the ARTCC sites. The other non-military, non-FAA sites will be included in this phase of the cutover process. Dual-distribution of NADIN messages will be terminated when all FAA sites have completed transition. As FAA users begin to cutover to AIS-R, message traffic to the current AIS will be discarded. The transition of all FAA sites will be completed by September 30, 2003.