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Global Communication, Navigation and Surveillance Systems (GCNSS)
US - FAA
INTRODUCTION
The National Airspace System (NAS) of the United States is one of the safest and most
productive in the world. However, the increasing demand for air travel, coupled with the
limitations of the current communication, navigation and surveillance (CNS) and air
traffic management (ATM) system have resulted in system delays and schedule
unreliability that impede the economical growth of airline industry. The overall goal of
GCNSS is to identify and evaluate new technologies that can overcome the capacity
limitations of the existing system while providing the safety and security required.
OBJECTIVES
The Global Communications, Navigation and Surveillance System (GCNSS) Program is
a 22-month, cost-sharing contract between FAA and Boeing’s Air Traffic Management
(BATM) business unit. Initiated in July 2002, the program has three prime objectives:
 Define the role and business case for satellites for CNS in ATM.
 Demonstrate a highly integrated, secure Surveillance Data Network (SDN) and
System Wide Information Management (SWIM).
 Demonstrate a broadband, two-way secure communications capability.
The GCNSS program translates the broad program objectives into specific goals to:
 Enhance air traffic capacity, efficiency and safety in regions that presently lack
communications, navigation and surveillance services.
 Enhance NAS capacity and efficiency through real-time flight trajectory
negotiations and information sharing during en route and terminal operations.
 Enhance common NAS situational awareness and collaboration for all service
providers, users and operators through real-time information sharing.
 Enhance safety against onboard threats through video and audio data transmission
from the aircraft to appropriate ground agencies.
GCNSS emphasizes the contributions that can be made to NAS operations through the
application of space-based technologies with a comprehensive SWIM system
incorporating both communications and secure data management functions. This overall
network-centric ATM operations concept envisions modernization of air traffic through
the introduction of hybrid -ground and space-based CNS architecture for global voice and
data communications that includes broadband capabilities for high-density traffic or large
data transfers. The aircraft becomes another node on the network able to receive and
share appropriate information to/from other nodes. Many important breakthroughs in
safety, capacity and operations are achievable from precise, shared information enabled
by SWIM.
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Figure: System Wide Information Management (SWIM)
The GCNSS demonstrations and simulations program consists of three time-phased
segments (Segments A, B & C) with a building block approach that integrates the efforts
of systems engineering and associated modeling and scenarios work. Segment A,
completed in the spring of 2003, emphasized the aviation safety and security
requirements from FAA and Transportation Security Administration (TSA) perspectives.
Segment B, scheduled for late 2003, will demonstrate the feasibility of satellite-based
communications and Automatic Dependent Surveillance (ADS) to enable precision,
radar-like control in oceanic and remote domains. Segment C, in early 2004, will
demonstrate the feasibility of a SWIM that will enable secure network-centric operations
between Air Traffic Control (ATC) centers, aircraft, airline operation centers and other
subscribers. Surveillance and other data will be published on the network and be
available to all.
During Segment A, there were a number of simulation activities, hardware in-the-loop
laboratory exercises and two demonstration flights with various airborne demonstrations.
During the flights, narrowband Iridium and broadband Ku-band satellite communication
links allowed the operation of live video, audio and data exchanges between on- and offboard systems. In the area of situational awareness, capabilities were demonstrated to
monitor the cockpit and cabin areas with video surveillance and audio monitors, to detect
alarms initiated by signal devices or Federal Air Marshall (FAM) Personal Digital
Assistant (PDA) devices and to exchange images and text/voice with these devices, both
from and to the ground and inter-plane, between FAMs. Data from the aircraft flight
monitoring system was continuously down-linked, giving real-time ground operator alerts
of flight path deviations. Environmental conditions outside the aircraft, specifically
temperature and wind data, was down-linked for ground display in text form. Composite
radar weather images were up-linked.
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The flight activities in Segment A demonstrated currently available technology. The
capability exists, using satellites, to greatly expand the type of information that can be
down-linked from an aircraft and the monitoring of flight situations as they develop.
Three demonstration Segment B flights in November 2003 will focus on aspects of a
global, integrated CNS architecture using satellite-based CNS. Demonstrations will
include direct controller-pilot two-way data-link, direct controller-pilot two-way “party
line” voice communications (digitized voice), radar-like surveillance using ADS via
satellite and seamless transition between domains (domestic and oceanic/off-shore).
Conducted in the Gulf of Mexico, this phase of the GCNSS work is also looking for nearterm enhancements to address surveillance and communications deficiencies in the Gulf.
Demonstration Segment C focuses on the SWIM concepts. Flights in this segment will
be performed by general aviation aircraft in a specified area. The primary purpose is to
demonstrate the feasibility of a SWIM system that will enable network-centric operations
among centers, aircraft, airlines, and security and defense agencies. Aircraft ADS will be
transmitted via satellite to an SDN which will integrate with multiple ground sensors to
eliminate surveillance boundaries. This live surveillance picture will be available to a
number of demonstration nodes incorporating additional simulated aircraft. Viability of
the communication links will also be demonstrated.
CONCLUSION
In the final analysis, the GCNSS will address specific controller issues and needs as
outlined below:

Oceanic/remote operations and procedures need to be made as similar to domestic
radar environment control procedures as possible. Controllers require accurate,
reliable, high-integrity means of tracking aircraft operating in oceanic/remote
regions. Satellite communications will enable a surveillance picture that permits
uniform separation standards.

Controllers require reliable, high-integrity voice and data communications with all
aircraft operating in controlled oceanic/remote airspace. Satellite communication
will provide this capability.

Controllers, both nationally and internationally, need a fast, reliable, and secure
means of coordinating flight data information and changes. Satellite-based
systems can enable the implementation of seamless, global ATM systems.

Controllers, flight operations centers (FOCs) and pilots need a means of obtaining
the most current and relevant weather and NAS status data in order to plan and
manage flight trajectories. This includes the sharing of weather information
provided by aircraft sensors. Broadband, satellite communications will provide
this capability.
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
Controllers and appropriate security agencies must have a clear picture (video and
audio) of actual, real-time events on an aircraft during emergencies with or
without cooperation from an onboard source. Once again, a broadband, satellite
communications capability.
The combination of these capabilities will provide controllers, ATM, TSA and other
agencies a much improved, real-time picture of aircraft situations in normal, non-normal
and emergency conditions. The sum of these capabilities will allow controllers the
ability to manage traffic in oceanic/remote regions as effectively as in domestic regions,
improve arrival management efficiency, improve overall ATM coordination and
situational awareness and enhance national security. A global, boundary free airspace is
the goal. GCNSS is demonstrating the feasibility of this goal and performing the
engineering analysis.
References:
1. NAS
 NAS Operational Evolution Plan (OEP) V. 4.0, December 2001
 National Airspace System Architecture Version 4.0, January 1999
2. Other Industry Documents
 Gulf of Mexico Work Group (GOMWG) Strategic Plan, February 1, 2001
 ICAO, Annex 10, Convention on International Civil Aviation (Chicago
Convention of 1944), International Civil Aviation Organization, Annex 10
 RTCA DO-225, VHF Air-Ground Communications System Improvements
Alternatives Study and Selection of Proposals for Future Action, November 17,
1994