1. FAA Data Communications Program System Engineering
AERONAUTICAL COMMUNICATIONS PANEL (ACP)   THIRTEENTH MEETING OF THE WORKING GROUP I   Bangkok, Thailand 27 – 28 January INFORMATION PAPER FAA use of ATN over SCTP
R. Morgenstern, MITRE
FAA Data Communications Program System Engineering

2. FAA Data Communications: Scope
TOWER
Data Comm Services
Aircraft
Avionics
CENTER
Data Comm Services
The Data Communications mission is threefold:
1 ) To improve efficiency by enabling controllers to handle more traffic, which will reduce delays and contribute to reduced operating costs for the airspace users and the FAA.
2) To enable advanced NextGen operations– operations not possible using voice, and which will contribute to increasing traffic throughput and to reduced operating costs for the airspace users and the FAA.
3) To improve safety by reducing the number of communications-related operational errors. Currently 20% of the operational errors are voice-related and of these 30% are high severity errors..
o Reduced number of read back / hear back errors
o Less stepped-on communications
o Enduring information on clearances at both the controller position and the cockpit
o An alternate communication path when pilot is on the wrong frequency or there is a stuck microphone
The short program definition is to provide safety, critical data exchange between controllers, automation, and flight crews for air traffic control in domestic airspace.
To implement Data Communications involves incorporation of Data Comm requirements into the domain automation platforms to generate and process the data messages. Also, within the scope of the program is the procurement of the transmission links (ground/ground and air/ground communications services) to carry the data from FAA facility to the aircraft, controller to flight crew.
Data Comm will add a flexible air/ground infrastructure that can rapidly adjust to changes in numbers of networked facilities. Network Operations Center – 3, Atlanta, Salt Lake, Tech Ctr.
APPROACH
Air-Ground
Data Comm
Network Service
Data Comm Services 2

3. DCP Architecture

4. NAS Boundary Protection
Processors in NAS Enterprise Security Gateway (NESG) terminate all in-bound connections and proxy applications

5. Protocol Gateway
Since the Protocol Gateway (PGW) processor is terminating TP4 connection to aircraft, FAA decided to also convert protocols to IPS to simplify End System (ES) and intervening network implementations
Utilizing SCTP (IETF RFC 4960) to manage line failures
Using a modified ICAO Doc 9896 Dialog Service to communicate between PGW and ES
Supports both ATN and FANS
Use TCP requirements in Doc 9896 as model for SCTP

6. Protocol Stack
PGW Dialog Service – Modified ICAO Doc 9896 Dialog Service
Multiplexing Service – Supports ground routing to ES
Connectivity Service – Supports management of failovers

7. FANS Support Use D_UNIT_DATA for connectionless communications
Encode SMI at beginning of User Data
Aircraft Registration field used as aircraft Peer ID
Utilize new Application Technology Type encodings to signal FANS message with and without Message Assurance encoding
Use 16-bit sequence number to support Message Assurance Service (MAS)
Use D_ACK message to convey A620 notifications to ES via added User Data
MAS Reports, Service Messages, Reject Messages, Outage notifications