2005 FRP Web
2005 FRP Web
2005 FRP Web
FEDERAL
RADIONAVIGATION
PLAN
Published by
Department of Defense,
Department of Homeland Security,
and Department of Transportation
iii
1.6.4.3 Role of the Private Sector ................................... 1-9
1.6.5 International Considerations ............................................ 1-9
1.6.6 Interoperability Considerations........................................ 1-10
1.6.7 Radio Frequency Spectrum Considerations..................... 1-10
iv
3.3 Mitigating Disruptions to Satellite Navigation Services .................. 3-12
3.3.1 Mitigating Disruptions in Aviation Operations.............. 3-12
3.3.2 Mitigating Disruptions in Maritime Operations ............. 3-13
3.3.3 Mitigating Disruptions in Land Operations.................... 3-14
3.3.3.1 Mitigating Disruptions in Railroad Operations.. 3-15
3.3.4 Mitigating Disruptions in Non-Navigation Applications 3-15
3.3.5 Mitigating Disruptions in NASA Applications .............. 3-16
3.3.6 DoD GPS Security Program.......................................... 3-16
3.4 DoD Certification of PPS Receivers ............................................... 3-17
v
List of Figures
vi
Executive Summary
The Federal Radionavigation Plan (FRP) is the official source of radionavigation policy
and planning for the Federal Government. The FRP covers common-use, Federally
operated radionavigation systems. These systems are sometimes used in combination
with each other or with other systems. Systems used exclusively by the military are
covered in the Chairman, Joint Chiefs of Staff (CJCS) Master Positioning, Navigation,
and Timing Plan (MPNTP). The plan does not include systems that mainly perform
surveillance and communication functions. The policies and operating plans contained in
this document cover the following radionavigation systems:
• Global Positioning System (GPS) • Tactical Air Navigation (TACAN)
• Augmentations to GPS • Instrument Landing System (ILS)
• Loran-C • Microwave Landing System (MLS)
• VOR and DME • Aeronautical Nondirectional
Radiobeacons (NDB)
The Federal Government operates radionavigation systems as one of the necessary
elements to enable safe transportation and encourage commerce within the United States.
It is a goal of the Government to provide this service in a cost-effective manner. The
Department of Transportation (DOT) is responsible under Title 49 United States Code
(U.S.C.) Section 101 for ensuring safe and efficient transportation. The Department of
Defense (DoD) is responsible for maintaining aids to navigation required exclusively for
national defense. The DoD is also required by 10 U.S.C. 2281(b) (Ref. 1) to provide for
the sustainment and operation of GPS for peaceful civil, commercial, and scientific uses
on a continuous worldwide basis free of direct user fees.
vii
A major goal of the DoD and the DOT is to ensure that a mix of common-use (civil and
military) systems is available to meet user requirements for accuracy, reliability,
availability, continuity, integrity, coverage, operational utility, and cost; to provide
adequate capability for future growth; and to eliminate unnecessary duplication of
services. Selecting a future radionavigation systems mix is a complex task, since user
requirements vary widely and change with time. While all users require services that are
safe, readily available and easy to use, the military has more stringent requirements
including performance under intentional interference, operations in high-performance
vehicles, worldwide coverage, and operational capability in severe environmental
conditions. Cost is always a major consideration that must be balanced with a needed
operational capability.
As the full civil potential of GPS and its augmentations is realized, the services provided
by other Federally provided radionavigation systems may be phased down to match the
reduction in demand, provided those services are not a part of a back-up navigation
strategy for critical applications or safety-of-life services.
The Federal Government conducts research and development (R&D) activities relating to
Federally provided radionavigation systems and their worldwide use by the U.S. armed
forces and the civilian community. Civil R&D activities focus mainly on enhancements
of GPS for civil uses. Military R&D activities mainly address military mission
requirements and national security considerations.
A detailed discussion of agencies’ roles and responsibilities, user requirements, and
system descriptions can be found in the companion document to the FRP entitled Federal
Radionavigation Systems (FRS).
The FRP is composed of the following sections:
Section 1 - Introduction to the Federal Radionavigation Plan: Delineates the
purpose, scope and objectives of the plan and presents the DoD, DOT, and other Federal
agencies’ roles and responsibilities for providing radionavigation services. In addition,
Section 1 discusses radionavigation system selection considerations.
Section 2 - U.S. Policies for Radionavigation Systems: Describes the U.S. policy for
providing each Federal radionavigation system identified in this document.
Section 3 - Operating Plans for Radionavigation Systems: Summarizes the plans of
the Federal Government to provide general-purpose and special-purpose radio aids to
navigation for use by the civil and military sectors.
Section 4 - Research and Development Summary: Presents the research and
development efforts planned and conducted by DoD, DOT, DHS, and other Federal
organizations.
Appendix A - Definitions
Appendix B - Glossary
References
viii
1
Introduction to the Federal
Radionavigation Plan
This section describes the background, purpose, and scope of the Federal
Radionavigation Plan (FRP). It summarizes the events leading to the preparation of this
document, the national objectives for coordinating the planning of radionavigation
services, and radionavigation authority and responsibility.
1.1 Background
The first edition of the FRP was released in 1980 as part of a Presidential Report to
Congress, prepared in response to the International Maritime Satellite (INMARSAT) Act
of 1978. It marked the first time that a joint Department of Transportation (DOT) and
Department of Defense (DoD) plan for radionavigation systems had been developed.
Now, this biennially updated plan serves as the planning and policy document for all
present and future Federally provided radionavigation systems. With the transfer of the
United States Coast Guard (USCG) from DOT into the Department of Homeland
Security (DHS) through PL 107-296 (116 Stat. 2135), this edition of the FRP marks the
first time the document has been signed by the Secretaries of Defense, Transportation,
and Homeland Security.
A Federal Radionavigation Plan is required by 10 United States Code (U.S.C.) 2281(c)
(Ref. 1). A Memorandum of Agreement (MOA) (Ref. 2) between DoD and DOT
provides for radionavigation planning as well as for the development and publication of
the FRP. This agreement recognizes the need to coordinate all Federal radionavigation
system planning and to attempt, wherever consistent with operational requirements, to
utilize common systems. In addition, a Memorandum of Agreement (Ref. 3) between the
1-1
DoD and DOT on the civil use of the Global Positioning System (GPS) establishes
policies and procedures to ensure an effective working relationship between the two
Departments regarding the civil use of GPS.
1.2 Purpose
The purpose of the FRP is to:
• Present the current U.S. Government policy and plan for operating civil and
military radionavigation systems.
• Outline the Government’s approach for implementing new and consolidating
existing radionavigation systems.
• Provide government radionavigation system planning information and schedules.
• Identify or clarify dual-use (i.e., used by both civil and military) radionavigation
system issues.
1.3 Scope
This plan covers Federally provided radionavigation systems. The plan does not include
systems that mainly perform surveillance and communication functions.
The systems addressed in this FRP are:
• Global Positioning System (GPS)
• Augmentations to GPS (See Section 2.2.2)
• Loran-C
• Tactical Air Navigation (TACAN)
• Instrument Landing System (ILS)
• Microwave Landing System (MLS)
• Aeronautical Nondirectional Beacons (NDB)
• Very High Frequency (VHF) Omnidirectional Range (VOR) and Distance
Measuring Equipment (DME)
1.4 Objectives
The objectives of U.S. Government radionavigation system policy are to:
• Strengthen and maintain national security.
• Provide safety of travel.
• Promote efficient transportation.
1-2
• Promote increased transportation capacity and mobility.
• Help protect the environment.
• Contribute to the economic growth, trade, and productivity of the United States.
1-3
responsibilities is contained in the companion Federal Radionavigation Systems (FRS)
document (Ref. 4).
1-4
1.6.1 Operational Considerations
1-5
1.6.1.3 Review and Validation
The DoD radionavigation system requirements review and validation process:
• Identifies the unique components of mission requirements.
• Identifies technological deficiencies.
• Determines, through interaction with DOT and DHS, the impact of new military
requirements on the civil sector.
• Investigates system costs, user populations, and the relationship of candidate
systems to other systems and functions.
1-6
1.6.2.1 Vulnerability of GPS in the National Transportation Infrastructure
The Final Report of the President’s Commission on Critical Infrastructure Protection
concluded that GPS services and applications are susceptible to various types of radio
frequency interference, and that the effects of these vulnerabilities on civilian
transportation applications should be studied in detail. As a result of the report,
Presidential Decision Directive 63 gave the Department of Transportation the following
directive:
The Department of Transportation, in consultation with the Department of
Defense, shall undertake a thorough evaluation of the vulnerability of the
national transportation infrastructure that relies on the Global Positioning
System. This evaluation shall include sponsoring an independent, integrated
assessment of risks to civilian users of GPS-based systems, with a view to
basing decisions on the ultimate architecture of the modernized NAS on
these evaluations.
The Volpe National Transportation Systems Center (Volpe Center) conducted this
evaluation and identified GPS vulnerabilities and their potential impacts to
aviation, maritime transportation, railroads, highway, and non-positioning
systems. The final report, Vulnerability Assessment of the Transportation
Infrastructure Relying on the Global Positioning System (Ref. 7), was published
on September 10, 2001 and is available on the Coast Guard Navigation Center
website www.navcen.uscg.gov. The report’s main conclusion is that GPS has
vulnerabilities for civilian users of the national transportation infrastructure. The
report also states that care must be taken to ensure that adequate back-up systems
or procedures can be used when needed.
The Volpe report offered several key recommendations for improving the safety
and efficiency of the national transportation infrastructure while preserving
security by ensuring back-up systems and operating procedures in the event of
loss of GPS service. The Secretary of Transportation accepted the
recommendations contained in the report and requested each modal Administrator
to develop plans for mitigating the risks associated with loss of GPS services.
The 2004 U.S. Space-Based Positioning, Navigation, and Timing Policy states
that GPS shall be maintained as a component of multiple sectors of the U.S.
Critical Infrastructure, consistent with Homeland Security Presidential Directive-
7. It also defines responsibilities for locating and resolving interference. The
mitigation of disruptions to satellite-based navigation services is discussed in
Section 3.3.
1-7
and to allow adequate time for the transition to newer more accurate systems and user
equipment; however, older systems must be periodically evaluated to determine whether
the systems are needed or are cost effective.
In many instances, aids to air navigation that do not economically qualify for ownership
and operation by the Federal Government are needed by private, corporate, or state
organizations. While these non-Federally owned/operated systems do not provide
sufficient economic benefit on a national scale, they may provide significant economic
benefit to specific user groups or local economies. In most cases they are also available
for public use. The FAA regulates and inspects aviation facilities in accordance with
Federal Aviation Regulations, Title 14 Part 171 of the Code of Federal Regulation (CFR)
Non-Federal Navigation Facilities, and FAA directives.
1-8
frequencies. As such, DHS, in coordination with DOT and DoD, and in cooperation with
other Departments and Agencies, coordinates the use of Federal capabilities and
resources to identify, locate, and attribute any interference within the United States that
adversely affects GPS and its augmentations.
Air navigation facilities, owned and operated by non-Federal service providers, are
regulated by the FAA under Title 14 Part 171 of the CFR “Non-Federal Navigation
Facilities.” A non-Federal sponsor may coordinate with the FAA to acquire, install and
turn an air navigation facility over to the FAA for maintenance because waiting for a
Federally provided facility would cost too much in lost business opportunity. Non-
Federal facilities are operated and maintained to the same standards as Federally operated
facilities under an Operations and Maintenance Manual agreement with the FAA. This
program includes recurrent ground and flight inspections of the facility to ensure that it
continues to be operated in accordance with this agreement.
1-9
The goals of performance, standardization, and cost minimization of user equipment
influence the search for an international consensus on a selection of radionavigation
systems. The ICAO establishes standards for internationally used civil aviation
radionavigation systems. The IMO plays a similar role for the international maritime
community. The International Association of Marine Aids to Navigation and Lighthouse
Authorities (IALA) also develops international radionavigation guidelines. IMO reviews
existing and proposed radionavigation systems to identify systems that could meet the
requirements of, and be acceptable to, members of the international maritime community.
In planning U.S. radionavigation systems, consideration is also given to the possible
future use of internationally shared systems. In addition to operational, technical, and
economic factors, international interests must also be considered in the determination of a
system or systems to best meet civil user needs. International negotiations and
consultations occur under the auspices of the Department of State.
1-10
and ensuring adequate protection for existing services. Rights and responsibilities of
primary and secondary allocation incumbents and new entrants are considered on
specific, technically defined criteria.
Within the U.S., two regulatory bodies oversee the use of radio frequency spectrum. The
Federal Communications Commission (FCC) is responsible for all non-Federal use of the
airwaves, while the National Telecommunications and Information Administration
(NTIA) manages spectrum use for the Federal Government. As part of this process, the
NTIA hosts the Interdepartment Radio-Advisory Committee (IRAC), a forum consisting
of Executive Branch agencies that act as service providers and users of Government
spectrum, including safety-of-life bands. The FCC participates in IRAC meetings as an
observer. National transportation spectrum policy is coordinated through the DOT Office
of Navigation and Spectrum Policy, Office of the Secretary (OST), while spectrum for
DoD is coordinated through the Assistant Secretary of Defense for Networks and
Information Integration (NII).
The broadcast nature of radionavigation systems also provides a need for U.S. regulators
to go beyond domestic geographic boundaries to coordinate with other nations through
such forums as the International Telecommunication Union. The ITU is a specialized
technical arm of the United Nations (UN), charged with allocating spectrum on a global
basis through the actions of the World Radiocommunication Conference (WRC), held
every 3-4 years. As a result of the WRC process, where Final Resolutions hold treaty
status among participating nations, spectrum allocations stay relatively consistent
throughout the world, and end users can use the same radionavigation equipment free
from RFI regardless of where they operate.
1-11
• Radionavigation Service (RNS)
The certification and use of radionavigation services is the shared responsibility of the
DOT, DHS, and DoD. The DOT, DHS, and DoD are Federal users of spectrum, as well
as service providers and operators of radionavigation systems. Within DOT, the FAA use
of spectrum is primarily in support of aeronautical safety services used within the NAS.
Within DHS, the USCG uses spectrum to operate radionavigation systems used on
waterways, specifically NDGPS and Loran-C.
Other DOT agencies (FRA, FHWA, FTA, and NHTSA) also work with private sector
and state and local governments to use spectrum for Intelligent Transportation System
(ITS) and Intelligent Railroad System applications. Many ITS applications will use GPS
and other radiodetermination systems to make roadway travel safer and more efficient by
providing differential corrections and location information in an integrated systems
context. Intelligent Railroad System, Positive Train Control, Rail Defect Detection, and
Automated Rail Surveying rely on NDGPS and rail industry telecommunications
frequencies to improve safety, efficiency, and effectiveness. Spectrum used for the
transportation, military, and homeland security applications must remain free from
interference due to public safety requirements.
1-12
2
U.S. Policies for Radionavigation Systems
This section sets forth the policy for Federally provided radionavigation systems.
2.1 General
The Federal Government operates radionavigation systems as one of the necessary
elements to enable safe transportation and encourage commerce within the United States.
A goal of the Government is to provide radionavigation services to the public in the most
cost-effective manner possible.
As the full civil potential of GPS services and its augmentations are implemented, the
demand for services provided by other Federally provided radionavigation systems is
expected to decrease. The Government will reduce non-GPS-based radionavigation
services with the reduction in the demand for those services. However, it is the policy of
the U.S. Government not to rely on a single system for positioning, navigation, and
timing. The U.S. Government will maintain back-up capabilities to meet (1) growing
national, homeland, and economic security requirements, (2) civil requirements, and (3)
commercial and scientific demands. Operational, safety, and security considerations will
dictate the need for complementary navigation systems to support navigation or conduct
certain operations. While some operations may be conducted safely using a single
radionavigation system, it is Federal policy to provide redundant radionavigation service
where required. Backups to GPS for safety-of-life navigation applications, or other
critical applications, can be other radionavigation systems, or operational procedures, or
2-1
a combination of these systems and procedures to form a safe and effective backup.
Backups to GPS for timing applications can be a highly accurate crystal oscillator or
atomic clock and a communications link to a timing source that is traceable to UTC.
When the benefits, including the safety benefits, derived by the users of a service or
capability are outweighed by its cost, the Federal Government should no longer continue
to provide that service or capability. A suitable transition period will be established prior
to decommissioning of Federal radionavigation services, based on factors such as user
equipment availability, radio spectrum transition issues, cost, user acceptance, budgetary
considerations, and the public interest. International commitments will affect certain
types and levels of navigation services provided by the Federal Government to ensure
interoperability with international users.
Radionavigation systems established primarily for safety of transportation and national
defense also provide significant benefits to other civil, commercial, and scientific users.
In recognition of this, the Federal Government will consider the needs of these users
before making any changes to the operation of radionavigation systems.
The U.S. national policy is that all radionavigation systems operated by the U.S.
Government will remain available for peaceful use subject to direction by the President in
the event of a war or threat to national security. Operating agencies may cease operations
or change characteristics and signal formats of radionavigation systems during a dire
national emergency. All communications links, including those used to transmit
differential GPS corrections and other GPS augmentations, are also subject to the
direction of the President.
2.2.1 GPS
GPS is a multi-use, space-based radionavigation system owned by the U.S. Government,
and operated by the DoD, to meet National and homeland security, civil, commercial, and
scientific needs. The U.S. Space-based PNT Policy established a new National Space-
based PNT Executive Committee (National PNT EXCOM) co-chaired by the Deputy
Secretaries of the Department of Defense and Transportation. The National PNT
EXCOM will make recommendations to its member Departments and Agencies, and to
the President through the representatives of the Executive Office of the President, advise
and coordinate on strategic decisions regarding policies, architectures, requirements, and
resource allocation for GPS and its augmentations. Its function is to ensure that national
security, homeland security, and civil requirements receive full and appropriate
consideration in Department decision-making processes. This new structure is intended to
ensure that civil, as well as military, needs are properly considered in the future
development and modernization of GPS. The National PNT EXCOM replaced the
Interagency GPS Executive Board.
The GPS provides two levels of service: SPS which uses the coarse acquisition (C/A)
code on the L1 frequency, and PPS which uses the P(Y) code on both the L1 and L2
2-2
frequencies. Access to the PPS is restricted to U.S. armed forces, U.S. Federal agencies,
and selected allied armed forces and governments. These restrictions are based on U.S.
national security considerations. The SPS is available to all users on a continuous,
worldwide basis, free of any direct user charge.
The specific capabilities provided by SPS are published in the Global Positioning System
Standard Positioning Service Performance Standard (Ref. 8) available on the Coast
Guard Navigation Center website: www.navcen.uscg.gov.
The National Geospatial-Intelligence Agency (NGA) determines the post-fit GPS precise
ephemeris which is considered DoD truth. NGA operates a global network of 11 GPS
monitor stations geographically placed to complement the Air Force monitor stations.
NGA stations are well controlled with complete redundancy in key components and
provide high quality data. NGA also provides products for positioning, navigation, and
timing. GPS products from NGA can be found at http://earth-info.nga.mil/GandG/sathtml.
The U.S. Government has determined that two additional coded civil signals are required
for certain civilian applications. A second civil signal will be added at the GPS L2
frequency designated as L2C. A third civil signal will also be added at 1176.45 MHz to
meet the needs of critical safety-of-life applications such as civil aviation. The third civil
signal is designated as L5.
GPS will be the primary Federally provided radionavigation system for the foreseeable
future.
GPS will be augmented and improved to satisfy future military and civil requirements for
accuracy, coverage, availability, continuity, and integrity.
2-3
applications. It serves as the basis for the National Spatial Reference System,
defining high accuracy coordinates for all CONUS-based Federal radionavigation
systems. Historically, CORS served post-processing users of GPS, but is being
modernized to support real-time users at a similar level of accuracy.
Global Differential GPS (GDGPS): GDGPS is a high accuracy GPS
augmentation system, developed by Caltech’s Jet Propulsion Laboratory (JPL), to
support the real-time positioning, timing, and determination requirements of
NASA’s science mission. GDGPS offers a host of real-time and near-time
products. The following products are freely available to the public: raw data from
the GDGPS tracking network (hourly), sea surface height from the Jason ocean
altimetry satellite (approximately every 3 hours), images of the global distribution
of ionospheric total electron content (real-time) and, finally, GPS constellation
status, global performance metrics, and situational assessment (real-time).
Additional information may be obtained from the GDGPS website:
http://www.gdgps.net. GDGPS also contributes data to the International GNSS
Service (IGS). IGS is a service that provides the highest quality data and products
in support of Earth science research, multidisciplinary applications, and
education, as well as to facilitate other applications benefiting society. IGS
advocates an open data, and equal access, policy.
2.2.3 Loran-C
Loran-C is a stand-alone, hyperbolic radionavigation system that provides horizontal
coverage throughout the 48 conterminous states, their coastal areas, and most of Alaska
south of the Brooks Range. It supports positioning, navigation, and timing services for
air, land, and marine users.
The Government continues to operate the Loran-C system in the short term while
evaluating the long-term need for the system. If a decision is made to discontinue Loran
as a result of these evaluations, then at least six months notice will be provided to the
public prior to the termination of service.
2.2.4 VOR/DME
VOR/DME provides users with a means of air navigation in the NAS. VOR/DME will
continue to provide navigation services for en route through nonprecision approach
phases of flight throughout the transition to satellite-based navigation. The FAA plans to
reduce VOR services provided in the NAS based on the anticipated decrease in use of
VOR for en route navigation and instrument approaches.
The FAA plans to install additional low-power DMEs to support ILS precision
approaches as recommended by the Commercial Aviation Safety Team. The FAA may
also need to sustain, modify or expand the existing DME services to provide a redundant
area navigation (RNAV) capability for terminal area operations at major airports and to
provide continuous coverage for RNAV operations at en route altitudes.
2-4
2.2.5 TACAN
TACAN is the military counterpart of VOR/DME. It is an airborne, ground- or ship-
based radionavigation system that combines the bearing capability of VOR and the
distance-measuring function of DME. The azimuth service of TACAN primarily serves
military users whereas the DME serves both military and civil users. The DoD
requirement and use of land-based TACAN will continue until aircraft are properly
integrated with GPS, and GPS-PPS is approved for all appropriate operations in national
and international controlled airspace.
2.2.6 ILS
The Instrument Landing System is the predominant system supporting precision
approaches in the U.S. With the advent of GPS-based precision approach systems, the
role of Category I ILS will be reduced. ILS will continue to provide precision approach
service at major terminals.
2.2.7 MLS
The FAA has terminated the development of the Microwave Landing System and does
not anticipate installing additional MLS equipment in the NAS. MLS service is expected
to be phased out beginning in 2010.
2-5
3
Operating Plans for Radionavigation Systems
This section summarizes the plans of the Federal Government to provide radionavigation
systems and services for use by the civil and military sectors. It focuses on three aspects
of planning: (1) the efforts needed to maintain existing systems in a satisfactory
operational configuration; (2) the development needed to improve existing system
performance or to meet unsatisfied user requirements in the near term; and (3) the
evaluation of existing and proposed radionavigation systems to meet future user
requirements. Thus, the plan provides the framework for operation, development, and
evolution of systems.
3-1
3-2
(1) Service will be retained in Alaska, in certain offshore areas, and for international gateways.
(2) Operation beyond 2006 depends upon further analysis by DHS.
(3) Planned dates-reference current planning documents for GPS.
(4) The end of development activities associated with WAAS single-frequency performance.
GPS modernization is a multi-phase effort to be executed over the next 15 or more years.
Additional signals are planned to enhance the ability of GPS to support civil users and
provide a new military code. The first new signal will be the new civil code on the L2
frequency (L2C - 1227.60 MHz). This signal, designated L2C, will enable dual-
frequency code-based civil receivers to correct for ionospheric error. A third civil signal
will be added on the L5 frequency (1176.45 MHz) for safety-of-life applications and
other applications as appropriate. L5 can serve as a complementary signal to the GPS L1
frequency (1575.42 MHz) with a goal of assurance of continuity of service potentially to
provide precision approach capability for aviation users. In addition, a secure and
spectrally separated Military Code (M-Code) will be broadcast on the L1 and L2
frequencies. The first launch of an L2C capable satellite is scheduled for 2005, and the
first launch of a L5 capable satellite is scheduled for 2007. Twenty-four L2C capable
GPS satellites are projected to be on orbit by approximately 2013, and 24 GPS L5
capable satellites are projected to be on orbit by approximately 2015. Prior to declaration
of Full Operational Capability (FOC), not all performance parameters of the new civil
signals will be met, and therefore the new signals will be available to users at their own
risk.
3-3
3.1.3.1 Nationwide Differential GPS (NDGPS)
The Coast Guard began development of a Maritime Differential GPS (MDGPS) system
in the late 1980’s to meet the needs of the Coastal and Harbor Entrance and Approach
(HEA) phases of navigation and to enable automated buoy positioning. The MDGPS
service was certified fully operational in March 1999 after the network met the
performance standards required for HEA navigation. Public Law 105-66 section 346
(Ref. 10) authorized the improvement and expansion of the Coast Guard MDGPS system
into a NDGPS system. Today, nine Federal agencies, several states, and scientific
organizations are cooperating to complete the NDGPS system throughout the U.S.
NDGPS currently meets all of the MDGPS FOC performance requirements as declared in
1999. NDGPS also supports the CORS system for post-processing survey applications,
the National Weather Service’s Forecast Systems Laboratory for short-term precipitation
forecasts, and the University NAVSTAR Consortium (UNAVCO) for plate tectonic
monitoring. Additionally, where operational considerations allow, additional operational
capability can be added, such as the broadcast of navigational or meteorological warnings
and marine safety information (i.e., NAVTEX data) to support safe navigation at sea.
When complete, NDGPS will provide uniform coverage of the conterminous U.S.,
Hawaii, and Alaska, regardless of terrain, man-made obstructions, or other surface
obstructions. This coverage is achieved by using a medium frequency broadcast
optimized for surface applications. The broadcast has been demonstrated to be
sufficiently robust to work throughout mountain ranges and other obstructions. Lastly,
the completed NDGPS system will provide a highly reliable GPS integrity function to
users that will enable applications such as Positive Train Control and precision
agriculture throughout the U.S.
Initial Operating Capability (IOC) is defined as providing users with coverage by at least
one NDGPS site over CONUS. FOC is defined as achieving dual coverage throughout
CONUS. Based on currently planned funding levels, IOC is projected for 2006 and FOC
is projected for 2009. As each new NDGPS site is added to the network, it is evaluated
and tested to ensure that it meets the full operational capability specifications. Once a site
is declared fully operational, the site is monitored and maintained by the USCG to ensure
support for safety applications. The most up-to-date system coverage for a specific area
can be obtained from the USCG Navigation Center website www.navcen.uscg.gov.
3-4
The WAAS will be incrementally expanded to increase the availability of service and
improve signal redundancy. In preparation for L5 on modernized GPS satellites, the FAA
will improve the WAAS to take advantage of this new signal. New dual-frequency
avionics using WAAS and L5 will potentially provide a GNSS Landing System (GLS)
precision approach capability (equivalent to ILS Category I operations).
3-5
3.1.3.4 Global Differential GPS (GDGPS)
The Global Differential GPS network consists of 70 dual-frequency GPS reference
stations operational since 2000. Future NASA plans include developing the TDRSS
Augmentation Service Satellites (TASS) to disseminate the GDGPS real-time differential
correction message to Earth satellites and enable precise autonomous orbit determination,
science processing, and the planning of operations in Earth orbit. The TASS signal will
be transmitted on S-band from NASA’s TDRSS satellites and also provide ranging signal
synchronized with GPS.
The International GPS Service to which GDGPS contributes data, was formally
recognized in 1993 by the International Association of Geodesy and began operations on
January 1, 1994. It is recognized as an international scientific service, and it advocates an
open data, and equal access, policy. NASA funds the IGS Central Bureau, which is
located at JPL, and a global data center located at the Goddard Space Flight Center
(GFSC). Over 10 years, IGS has expanded to a coordinated network of over 350 GPS
monitoring stations from 200 contributing organizations in 80 countries. Other
contributing U.S. agencies and organizations include, among others, the National Oceanic
and Atmospheric Administration/National Geodetic Survey, the U.S. Naval Observatory,
National Geospatial Intelligence Agency (NGA), and the National Science Foundation
(NSF). Its mission is to provide the highest quality data and products as the standard for
global navigation satellite systems (GNSS) in support of Earth science research,
multidisciplinary applications, and education, as well as to facilitate other applications
benefiting society. Approximately 100 IGS stations report with a latency of one hour.
This data, and other information, may be obtained from the IGS website at:
http://igscb.jpl.nasa.gov.
3.1.4 Loran-C
Loran-C is a stand-alone, hyperbolic radionavigation system that was originally developed
to provide military users with a radionavigation capability with greater coverage and
accuracy than its predecessor (Loran-A). It was subsequently selected as the
radionavigation system for civil marine use in the U.S. coastal areas. It is approved by the
FAA as a supplemental system in the NAS for the en route and terminal phases of flight
and by the USCG as a means of maritime navigation in the coastal confluence zone. It is
also available for use as either a primary or back-up precise frequency source to support
precise timing applications. The Department of Defense has determined that Loran is no
longer needed as a positioning, navigation, or timing aid for military users.
The Government continues to operate the Loran-C system in the short term while
evaluating the long-term need for the system. This evaluation consists of two elements: a
determination of the technical capability of a fully modernized and enhanced Loran system,
and a cost-benefit analysis of developing and operating an enhanced Loran system.
The first part of the evaluation was completed in April 2004. The Office of the Secretary of
Transportation, the FAA, and the USCG completed the technical evaluation of the ability
of an enhanced Loran system to support nonprecision approach operations for aviation
users and harbor entrance and approach operations for maritime users. As a result of and in
conjunction with the technical evaluation, a number of decisions have been made:
3-6
• With respect to technical capability, the evaluation determined that an enhanced
Loran system would be capable of providing nonprecision approach for aviation
users and harbor entrance and approach for maritime users.
• With respect to aviation, the FAA has determined that sufficient alternative
navigational aids exist in the event of a loss of GPS-based services, and therefore
Loran is not needed as a back-up navigation aid for aviation users.
• With respect to maritime safety, the USCG has determined that sufficient back-
ups are in place to support safe maritime navigation in the event of a loss of GPS-
based services, and therefore Loran is not needed as a back-up navigational aid
for maritime safety.
The second part of the overall evaluation is a cost-benefit analysis that is currently in
progress. Specifically, two aspects remain to be evaluated:
• The Maritime Administration is evaluating whether the back-up systems or
procedures currently employed in the Marine Transportation System are sufficient
for maintaining maritime efficiency in the event of loss of GPS services. MARAD
will update the USCG on progress throughout the study and solicit USCG input
into the findings and recommendations. MARAD will then make a determination
whether an enhanced Loran system is needed as a back-up navigation aid to
maintain commercial maritime efficiency. This determination is expected to be
completed by December 30, 2005.
• The Department of Homeland Security, in cooperation with DOT, is evaluating
whether precise timing is a part of the U.S. critical infrastructure and whether a
Federally provided back-up timing system is required. Concurrently, an analysis
of alternatives, including the Loran system, will be conducted. This determination
is expected to be completed by December 30, 2005.
DOT, in coordination with DHS, will make a decision regarding the future of the Loran
system by the end of 2006. If a decision is made to discontinue Loran, then at least six
months notice will be provided to the public prior to the termination of the service.
3-7
maintained at their current level until 2010 to enable aviation users to equip their aircraft
with GPS or GPS/WAAS avionics and to become familiar with the system. Plans for the
maintenance of the network are limited to site modernization or facility relocation and the
conversion of VORs having degraded signal propagation to a Doppler VOR
configuration.
A reduction in the VOR population (only) is expected to begin in 2010. The proposed
reduction will transition from today’s VOR services to a minimum operational network
(MON). The MON will support IFR operations at the busiest airports and serve as an
independent civilian backup navigation source to GPS and GPS/WAAS in the NAS.
Section 3.2 discusses the transition in more detail.
The FAA plans to sustain existing DME service to support en route navigation, and to
install additional low-power DMEs to support Instrument Landing System precision
approaches as recommended by the Commercial Aviation Safety Team. The FAA may
also need to expand the DME network to provide a redundant RNAV capability for
terminal area operations at major airports and to provide continuous coverage for RNAV
operations at en route altitudes.
3.1.6 TACAN
TACAN is a tactical air navigation system for the military services ashore, afloat, and
airborne. It is the military counterpart of civil VOR/DME. TACAN provides bearing and
distance information through collocated azimuth and DME antennas. TACAN is
primarily collocated with the civil VOR stations (VORTAC facilities) to enable military
aircraft to operate in the NAS and to provide DME information to civil users.
The FAA and DoD currently operate approximately 114 “stand-alone” TACAN stations
in support of military flight operations within the NAS. The DoD also operates
approximately 30 fixed TACAN stations that are located on military installations
overseas, and maintains 93 mobile TACANs and 2 mobile VORTACs for worldwide
deployment. The FAA and DoD continue to review and update requirements in support
of the planned transition from land-based to space-based primary navigation.
The DoD requirement for land-based TACAN will continue until military aircraft are
properly equipped with GPS, GPS PPS receivers are certified for all operations in both
national and international controlled airspace, and the GPS support infrastructure
including published procedures, charting, etc., is in place. A phase down of TACAN
systems is planned for a future date, yet to be determined. Sea-based TACAN will
continue in use until a replacement system is successfully deployed. The Navy, Coast
Guard and Military Sealift Command operate approximately 293 sea-based TACAN
stations.
3-8
3.1.7 ILS
The Instrument Landing System is a precision approach system consisting of a localizer
facility and a glide slope facility. It is frequently augmented by associated VHF marker
beacons, DME, visibility sensors, approach lighting systems, and nondirectional beacons.
An ILS provides vertical and lateral navigation (guidance) information during the
approach and landing phase of flight and is associated with a specific airport runway end.
Depending on its configuration and the other systems installed on the airport and in the
aircraft, an ILS can support Category I, II, and III approaches.
ILS is the standard civil precision approach system in the U.S. and abroad. The FAA
operates 1,275 ILS systems in the NAS of which 225 are localizer only and 115 of which
are Category II or Category III systems. In addition, the DoD operates 160 ILS facilities
in the U.S.
As the GPS-based augmentation systems (WAAS and Local Area Augmentation System
(LAAS)) are integrated into the NAS, and user equipage and acceptance grows, the
number of Category I ILSs will be reduced. The proposed reduction will transition from
today’s full-coverage network to a minimum operational network that will support IFR
operations at the busiest airports in the NAS. Section 3.2 discusses the transition in more
detail. LAAS is discussed in Section 4.2.1.
The FAA does not anticipate phasing out any Category II or III ILS systems until LAAS
is able to deliver equivalent service and GPS vulnerability concerns are addressed. A
reduction in the number of Category II/III ILSs may then be considered. Until LAAS
systems are available, new and upgrade Category II and III precision approach
requirements will continue to be met with ILS.
3.1.8 MLS
The FAA does not anticipate additional civil Microwave Landing System development.
The phase-down of MLS is expected to begin in 2010.
3-9
that define low-frequency airways in Alaska or serve international gateways and certain
offshore areas like the Gulf of Mexico will be retained.
VOR
Minimum Operating Network
DME
TACAN
NDB
Long-Range Systems – Alaska and Coastal
3-10
The FAA will conduct the planned reductions gradually, providing users sufficient time
to equip with Satnav avionics. The reductions are planned to begin in 2010 based on
projected satellite navigation program milestones, including the publication of
procedures, and anticipated user equipage rates.
The specific Navaids to be discontinued at each step of the transition will be determined
based on specific criteria, currently under development. The discontinuance criteria, and
a site-specific list of Navaids, will be published well ahead of the reductions. The
advanced site-specific notice will afford users the opportunity to plan their transition to
Satnav based upon the operational schedule for the specific Navaids they use most often.
The necessary amendments to those flight procedures that will remain after this transition
will be planned and completed before specific Navaids are discontinued.
• Interim Network – Many currently underutilized VORs and ILSs will be
discontinued in the early stages of the transition. Preliminary analysis indicates
that approximately 350 VORs and 300 ILSs could be discontinued, representing a
reduction to approximately 70 percent of the current Navaid population.
• Minimum Operational Network – When the transition is completed, the
population of ground-based Navaids will have been reduced to the level of a
proposed Minimum Operational Network that provides an independent back-up
radionavigation source. The MON will support continued operation in the NAS
by those aircraft not equipped with Satnav avionics at a reduced level of airspace
access or efficiency (e.g., more circuitous routes between some airports). The
MON will also provide the FAA and the airspace users with a safe recovery and
sustained operations capability in the event of a disruption in Satnav service. The
MON represents a reduction to approximately 50 percent of today’s VOR and
Category I ILS population.
3.2.2 Airport Implementation Issues
GPS represents a fundamental departure from traditional point-to-point, ground-based
navigation systems technology with respect to aviation approach operations. Ground-
based systems provide services that are somewhat limited to the location where they are
installed. A ground-based system (such as an ILS) only provides services to a single
runway. In theory, GPS approach operations can be made available to any existing
runway in the NAS with or without ground-based radionavigation equipment. However,
obstruction removal and other airport improvements are often needed to provide the full
benefit of GPS approach operations.
3-11
The FAA’s plans for the transition to Satnav and for the reduction of ground-based
Navaids will be periodically reevaluated. These plans need to remain flexible, and may
need to be adjusted as satellite navigation program milestones are achieved, as the actual
performance of Satnav systems is demonstrated, and as users equip with Satnav avionics.
The transition plans will continue to be coordinated with airspace users and with the
FAA’s air traffic control community.
The NAS is divided into hundreds of air traffic control “sectors.” A single air traffic controller has the responsibility to keep
aircraft safely separated from one another within each sector. Sector dimensions vary, and are established based on
predominant traffic flows, altitude, and controller workload.
3-12
In addition to FAA plans of retaining a minimum network of VOR, DME, and ILS
facilities to serve as a backup to GPS, several other solutions have been identified to help
mitigate the effects of a Satnav service disruption, but each has its limitations.
• The L5 civil frequency planned for GPS will help mitigate the impacts of both
solar activity and unintentional interference, but it may be 2015 before a full
constellation of dual-frequency satellites (L1 and L5) is available. When
implemented in WAAS, this signal will preserve LPV capability during severe
ionospheric activity.
• Modern transport-category turbojet aircraft with inertial systems, when engaged
in relatively stable en route flight, may be able to continue navigating safely for a
period of time after losing radionavigation position updating depending on the
route or procedure being flown. In some cases, this capability may prove adequate
to depart an area with localized jamming or proceed under visual flight rules
during good visibility and high ceilings. However, inertial performance without
radionavigation updates degrades with time and will eventually fail to meet
airspace requirements.
• Integrated GPS/inertial avionics having significant anti-jam capability could
greatly reduce the area affected by a GPS jammer or by unintentional
interference. Industry research is proceeding to develop this technology, with an
expectation that it might be marketed to the general aviation community.
However, significant technical challenges remain to be resolved to ensure that this
technology works correctly, and some users may still find this technology to be
unaffordable.
• Users may have an option to equip with instrument flight rules (IFR)-certified
Loran-C avionics, pending the improvements needed to achieve a nonprecision
instrument approach capability with Loran. A combined Loran/Satnav receiver
could provide navigation and nonprecision instrument approach service
throughout any disruption to Satnav service.
• If a majority of operations are conducted by aircraft equipped with an additional
navigation capability (e.g., inertial, DME, VOR or Loran), then the balance
should be able to be managed with air traffic control vectors based on an
independent (e.g., radar) surveillance system. Additional research may be
necessary to validate this concept in terms of the impact to air traffic controller
workload and the sensitivity to the proportion of backup-equipped aircraft.
3-13
paper charts and dead reckoning. In addition, the USCG controls waterway activity,
under the authority vested in the Captain of the Port by closing waterways or restricting
marine activity during adverse weather conditions or special operations. These combined
elements facilitate safe waterway navigation.
Rather than being identified as a weakness, universal AIS is an example of how a new
technology can be designed around GPS while at the same time implementing measures
that mitigate the impact of the potential vulnerabilities of GPS. Specifically, the universal
AIS design team has been aware of the potential GPS failure mechanisms. Although
Universal AIS uses GPS for primary timing, secondary timing is provided by an external
synchronization method that is based upon the reception of other AIS stations’
broadcasts. Loss of GPS timing will not prevent AIS from operating, although the
capability to apply accurate “time tags” to the data packets would be lost.
In the case of AIS, the architecture is structured to gracefully degrade with loss of the
primary position sensing system (like GPS). To accomplish this, it makes use of a
hierarchy of eight levels of position sensing systems with GPS/DGPS at the high end and
dead reckoning at the low end. For example, at the fourth stage of operation, the
electronic position source can be any external electronic position fixing system, such as
Loran-C. These eight stages provide for significant AIS survivability in the face of a
variety of navigation threats. The completeness of the navigation information will depend
upon the number and type of secondary navigation information sources actually
employed by the AIS aboard the vessel.
The USCG is working closely with other maritime nation members to address disruptions
through updated performance standards for GPS receivers to reduce vulnerability to
interference. The USCG continues to work with other committees that are improving
equipment standards or determining alternative solutions to better deal with these issues.
3-14
of GPS as well as what to do when failures occur may be necessary. Finally, since it is
expected that signal availability from GPS may not be adequate for surface users
experiencing canopy/urban obstructions, alternate systems that perform a verification test
on the GPS navigation solution and that support continued operation in the event of a loss
of GPS will be employed in a system-of-systems configuration.
3.3.3.1 Mitigating Disruptions in Railroad Operations
The Federal Railroad Administration’s Intelligent Railroad Systems initiative encourages
an integrated approach to technology that incorporates systems that are interoperable,
synergistic and redundant. For example, since GPS is susceptible to jamming and
unintentional interference, FRA encourages the use of technologies and procedures that
cannot be jammed or interfered with as a backup. These technologies and procedures
include inertial navigation systems, sensor circuits, signaling systems, and dispatcher
operations. These redundant systems and procedures ensure the safe and efficient
operation of the railroad system during the loss or disruption of GPS. Similarly, since all
radionavigation systems are susceptible to interference, radionavigation systems are not
considered acceptable backups to GPS for rail applications.
Recognizing that satellite navigation services can be disrupted, FRA will:
• Work towards bringing anti-jam capable receivers to the railroad industry.
• Encourage the incorporation of low cost Inertial Navigation Units (INU) in
Positive Train Control (PTC) systems.
• Develop the capability to update INUs automatically via inputs from railroad
sensors, and manually when a locomotive passes a milepost.
• Develop equipment standards and architectures for use in railroad applications.
• Advocate robust signal structures for satellite navigation services and their
augmentation systems such as NDGPS.
• Work with other agencies and the international community to prevent and
mitigate disruptions of satellite navigation services and their augmentation
systems such as NDGPS.
3-15
3.3.5 Mitigating Disruptions in NASA Applications
Dual-frequency GPS receivers have been certified for Space Shuttle navigation, and were
chosen for being less susceptible to disruption. As of December 2004, the status of the
Shuttle fleet is:
• OV-103 (Discovery) and OV-104 (Atlantis) have one PPS GPS receiver and three
TACAN units. A method of simultaneously using GPS and TACAN has been
developed, and will be used soon after the Shuttle return-to-flight (note: STS-
114/Discovery will not use GPS except during an emergency). Should GPS
service be disrupted, TACAN is available for navigation. Current plans call for a
Shuttle end-of-fight in 2010, well before TACAN phase-down.
• OV-105 (Endeavour) has had its TACAN units removed and, instead, will use
three PPS GPS receivers as the primary navaids for re-entry.
The Inertial Navigation System (INS), which is the primary navigation system, is updated
through position fixes from GPS (single string) and TACAN in OV-103 and OV-104, and
a three string GPS on OV-105. Therefore, brief disruptions in GPS would initially be
compensated by the INS. Should GPS service be disrupted prior to entry, emergency
procedures call for tracking using ground-based C-Band radar. Additional redundancy is
provided through drag and barometric altimeters, as well as Microwave Landing Systems
at the landing sites in Kennedy Space Center, Edwards, White Sands, as well as the
emergency launch-abort landing sites in France and Spain. During entry operations, the
landing sites may be monitored for interference to GPS. During re-entry, the landing site
at Kennedy Space Center is continuously monitored for GPS interference.
A number of GPS receivers have been tested on spacecraft for real-time navigation and
attitude determination. GPS facilitates autonomous operations in Earth orbit and reduces
operational costs and communications bandwidth. Should GPS service be disrupted, then
ground-based tracking could be used for navigation and on-board backup instruments
such as magnetometers, Earth sensors, and directional antennas for attitude
determination. Mitigations range from the use of lower accuracy navigation methods
(e.g., laser corner reflectors on the Jason ocean surface topography mission) to no
mitigation. For example, the GRACE gravity field measurements and COSMIC
ionospheric sensing and space weather satellite constellations which would lose the
primary science data during GPS signal interruptions.
In the December 2004 U.S. Space-Based Positioning, Navigation, and Timing Policy, the
President directed that the Secretary of Defense shall develop, acquire, operate,
realistically test, evaluate, and maintain navigation warfare capabilities.
The DoD Navigation Warfare (Navwar) program exists to ensure that the United States
retains a military advantage in an area of conflict by: protecting authorized use of GPS;
preventing the hostile use of GPS and its augmentations; and preserving civilian uses
outside an area of conflict.
3-16
This research and development (R&D) effort will require periodic testing which may
impact the civil use of GPS. DoD and DOT have developed mechanisms to coordinate
times and places for testing, and will notify users in advance.
3-17
4
Research and Development Summary
4.1 Overview
This section describes Federal Government radionavigation system research and
development (R&D) activities. It is organized in two segments: (1) civil R&D efforts to
be conducted by DOT and other Government organizations for civil purposes, and (2)
DoD R&D.
Civil R&D activities emphasize the enhancement of GPS for civil applications. Civil
R&D activities may involve evaluations and simulations of low-cost receiver designs,
evaluation of future technologies, and determination of future requirements for the
certification of equipment. DoD R&D activities mainly address enhancements
necessitated by national security considerations, extended military mission requirements,
and new civil requirements (e.g., the new second and third civil signals). Where
appropriate, civil agencies and the DoD exchange operational and technical information
on radionavigation systems R&D development programs.
4-1
In addition, the Research and Innovative Technology Administration is conducting a
series of research activities in transportation infrastructure assurance, including reviews
of system interdependencies and the vulnerability of systems related to electronic
commerce. Navigation and radionavigation systems are being included in the scope of
these projects.
4.2.1 Aviation
The FAA is conducting R&D in the LAAS program in conjunction with the introduction
of satellite navigation into the NAS. Research is also ongoing to support the procurement
of replacement DME, and to support a decision by the Department of Transportation
whether to continue operating the Loran-C system. The agency is also initiating a
program to pursue interference detection, location, and mitigation.
4.2.1.1 LAAS R&D Activities
LAAS is a ground-based GPS augmentation system being developed by the FAA. LAAS
is expected to provide the required accuracy, availability, integrity, coverage, and
continuity to initially support Category I precision approaches and eventually Category II
and III precision approaches.
LAAS will augment GPS by providing differential corrections to users via a VHF data
broadcast. LAAS will allow suitably equipped aircraft to conduct precision approaches in
the vicinity of LAAS-equipped airfields. LAAS will also allow suitably equipped aircraft
to conduct curved approaches, segmented approaches, and other RNAV approaches
within the terminal area.
The following items illustrate the research currently underway to support the Category I
and Category II/III LAAS capabilities:
Category I
• Quantify and characterize the rapid changes in ionospheric range delay, and
evaluate methods of mitigation.
Category II/III
4-2
• Perform analysis to confirm that proposed alert limits and time-to-alert can be
met with the LAAS architecture.
The FAA is studying the effects of the over-interrogation of currently operated DME
ground transponders. When too many interrogations are received from airborne DME
equipment, DME ground transponders become “saturated.” They typically respond by
rejecting weaker interrogations from more distant aircraft or from closer aircraft with
lower-powered DME interrogators. As a result, service can be denied to aircraft that are
within the expected coverage area of the DME. Aspects of the program include:
• Scoping a robust but affordable program that will prevent a loss in the projected
system gains achieved by the new NAS systems, and assure that the end users
benefit from the significant investments being made.
4.2.2 Maritime
The USCG is exploring accuracy enhancement and the integration of NDGPS with other
navigation sensors. Particular emphasis is being placed upon the integration of NDGPS
with inertial navigation systems. Efforts are being conducted to determine the ability of
4-3
INS to enhance GPS/DGPS navigation service, and to provide heading information for
Electronic Chart Display and Information System (ECDIS) use. Work is being conducted
with RTCM Special Committee 104 (SC104) in developing new high accuracy messages,
including ones optimized for use with Selective Availability (SA) set to zero. This work
includes the development of corrections for ranging signals broadcast from geo-stationary
satellites. Also, several promising improvements to the NDGPS data link are being
studied that have the potential to further mitigate the effects of impulse noise and
interference.
Increasing numbers of WAAS receivers have emerged in the public marketplace and are
being used in the maritime regions. As a result, comprehensive testing and evaluation of
WAAS accuracy, availability, and integrity required in maritime applications is being
conducted to determine if WAAS satisfies the performance requirements for maritime
navigation and positioning applications (e.g., buoy positioning, HEA navigation, and
inland waters navigation). The testing and evaluation involves a combination of shore
and vessel data collection, as well as WAAS modeling.
The Coast Guard is developing a set of analysis tools to allow performance evaluations of
navigation systems in specific ports and waterways. These tools will help assess the
relative level of safety expected from radio aids, navigation equipment, and short range
aids to navigation intended to be used for HEA navigation.
4.2.3 Land
GPS and its augmentations offer navigation services that far exceed what was envisioned
only a few short years ago. With the tremendous success of GPS and its current
augmentations, new applications requiring even more precise accuracy, integrity, and
availability are being discovered. FHWA, USCG, NOAA, and other Federal agencies, as
well as State and local governments, agencies, academia, and industry are working
together to develop more precise and robust augmentations for GPS, creating terrestrial
navigation systems that will significantly improve the safety and economic well being of
the nation. The goal is to achieve 10 cm real time navigation, a three to five second
integrity function, and an availability of greater than 99 percent. For non-safety-of-life
applications, the accuracy goals may be as stringent as 1 cm or better in real time.
4.2.3.1 High Accuracy NDGPS
The High Accuracy NDGPS (HA-NDGPS) system is currently under development in
order to enhance the performance of NDGPS. The first HA-NDGPS station began
broadcasting in a test mode in 2001 with funding from the Interagency GPS Executive
Board (IGEB). The IGEB recognized the potential benefit to many Federal agencies,
states, and the general public of having a nationwide high accuracy system. Two HA-
NDGPS reference stations are currently operational and providing 10 to 15 cm accuracy
throughout the coverage area. Further improvements to accuracy and the development of
1 to 2 second time-to-alarm integrity are anticipated. Once these improvements are
complete, a HA-NDGPS standard will be developed.
To support this, several approaches are being investigated. They can be grouped into
three general categories: improved ionosphere and troposphere prediction; increased data
4-4
throughput to support broadcast of GPS observables; and the addition of pertinent data to
the current broadcast. Each is discussed in the following sections.
Improved Ionosphere and Troposphere Prediction
Large errors and rapid changes in GPS positional accuracy can occur during significant
space and tropospheric weather events, and no currently available signal delay models
can provide high accuracy corrections under these conditions. FHWA, in collaboration
with the USCG and NOAA, is evaluating the feasibility of using weather models to
calculate GPS signal delays caused by the ionosphere and troposphere, create differential
correction messages for broadcast, and use them to help resolve carrier phase ambiguities
over arbitrarily long baselines.
Increased Data Throughput for Broadcast of GPS Observables
A second line of research is determining the feasibility of broadcasting navigation
satellite observables. The focus of this effort has been the development of a low cost
modification to existing NDGPS facilities in order to maximize the benefits of these
facilities. The NDGPS site near Hagerstown, MD, was modified in April 2002 and a
second site, Hawk Run, PA, was modified in July 2003. The effort has been divided into
two phases.
Phase I was a proof of concept and implementation phase that determined the viability of
modifying an NDGPS facility and examined the accuracy available from a single site. A
broadcast data rate of 1000 bps was established as the maximum allowable. A second
transmitter, transmission line, and diplexer were added to the Hagerstown NDGPS
facility.
Testing began shortly after installation. Testing using this single site achieved a
horizontal navigation solution of within 10 cm (95 percent) of truth at a range of
approximately 250 km. This testing is documented in the Phase I final report available at:
http://www.tfhrc.gov/its/ndgps/02110/index.htm.
Addition of Pertinent Data
With SA set to zero, differential GPS (DGPS) latency requirements for pseudorange
correction data can be eased and range rate data may no longer be needed by users.
Service providers are aggressively pursuing methods to leverage newly available data
link capacity to enhance system performance. Methods being explored include:
• Improved “post SA” reference station correction generation algorithms that
increase accuracy.
• Improved integrity monitoring processes that reduce user vulnerabilities.
• Differential corrections that enable use of WAAS pseudo-ranges in DGPS
position solutions.
• Enhanced beacon almanacs that enable users to intelligently select the best beacon
by signal specification.
4-5
• Highly accurate atmospheric corrections generated by NOAA using wet/dry
tropospheric and ionospheric data.
• Network distribution of correction data between adjacent beacon sites.
• Distribution of precise orbit data over the DGPS data link.
4.2.3.2 Application Development
The land transportation modes have been working for many years to establish supportable
values for navigation. In recent years, this effort has been focused on two primary land
transportation modes – rail and highway. In each mode, the lead Federal organization has
been working with private sector organizations to cooperatively analyze and develop
prototype systems to further evaluate the viability and effectiveness of the prototype,
ensuring that there is no loss in transportation safety.
4.2.4 Rail
The FRA in conjunction with other agencies and the railroad industry is working on the
development of Intelligent Railroad Systems that use sensors, computers, and digital
communications to collect, process, and disseminate information to improve the safety,
security, and operational effectiveness of railroads. Integral to many Intelligent Railroad
Systems is the requirement for the accurate, real-time, position of locomotives, rail cars,
maintenance-of-way vehicles, tracks, and wayside equipment through the use of
radionavigation and positioning services.
FRA’s Office of Research and Development is working with other Federal agencies,
states, universities, and industry to develop radionavigation and positioning services to
meet two FRA requirements. The first requirement is for a system that provides 1 meter
accuracy (95 percent), 6 second time to alarm integrity when the system is out of
tolerance and ubiquitous coverage over all U.S. railroads. When combined with other
sensors such as track circuits and INU, the combined system must be available 99.999
percent of the time and determine which track the train is on and whether or not the train
has cleared a switch with a degree of confidence 0.99999. These requirements are needed
for Positive Train Control and general train operations.
PTC is an integrated command, control, communications, and information system for
controlling train movements with safety, security, precision, and efficiency. PTC will
improve railroad safety by significantly reducing the probability of collisions between
trains, casualties to roadway workers and damage to their equipment, and over speed
accidents. The National Transportation Safety Board (NTSB) has named PTC as one of
its “most-wanted” initiatives for national transportation safety. PTC systems are
comprised of digital data link communications networks, continuous and accurate
positioning through the use of HA-NDGPS, on-board computers with digitized maps on
locomotives and maintenance-of-way equipment, in-cab displays, throttle-brake
interfaces on locomotives, wayside interface units at switches and wayside detectors, and
control center computers and displays. PTC systems issue movement authorities to train
and maintenance-of-way crews, track the location of the trains and maintenance-of-way
vehicles, have the ability to automatically enforce movement authorities, and continually
update operating data systems with information on the location of trains, locomotives,
cars, and crews. The remote intervention capability of PTC permits the control center to
4-6
stop a train should the locomotive crew be incapacitated. In addition to providing a
greater level of safety and security, PTC systems also enable a railroad to run scheduled
operations and provide improved running time, greater running time reliability, higher
asset utilization, and greater track capacity. FRA selected NDGPS to meet the positioning
requirements for PTC and is working with other Federal agencies, states, universities, and
industry to improve the accuracy of service and to expand it to provide dual coverage
nationwide.
The second FRA requirement is for a real-time, nationwide service that provides 10 cm
horizontal accuracy and 15 cm vertical accuracy for rail surveying, rail defect detection,
and scientific applications involving railroad test cars. FRA is working with other Federal
agencies, universities, and industries in the development of the HA-NDGPS to meet these
requirements. The first prototype HA-NDGPS site was installed at the Hagerstown,
Maryland NDGPS site. Both the high accuracy and original NDGPS are broadcast from
the reference station, so the users have backward compatibility to the original NDGPS
signal and can take advantage of the new high accuracy signal if needed. This prototype
site proved that 10 cm accuracy at distances of up to 250 km from the reference station
can be achieved. Agencies will continue to work to: improve the accuracy; improve the
range from the reference station that the high accuracy can be achieved; decrease the time
it takes to converge on the high accuracy solution; and ensure that the system is robust
enough for the railroad environment. After this prototype work is completed, a standard
will be developed, and the system will be implemented nationwide.
4.2.5 Highway and Transit
Highway applications today are focused on assisting travelers in routing or in fleet
management. Near term research is underway to examine the ability to provide warnings
to drivers of potential critical situations, such as stop sign violation or crashes. Longer-
term research is examining the potential for minimal vehicle control when there is a clear
need for action. This could take the form of pre-deployment of air bags to braking.
The Intelligent Vehicle Initiative (IVI) is examining the long-term needs of the
transportation system. The IVI research currently underway is in the area of advanced
driver assistance systems, which include road departure and lane change collision
avoidance systems. These systems need to estimate the lateral position of the host vehicle
relative to lane and road edge with an accuracy of 10 cm. The IVI program is engaged in
a research program to determine if the position accuracy of the vehicle can be determined
with radionavigation techniques coupled with inertial sensors.
Most transit agencies now procure Automatic Vehicle Location systems that use GPS. In
the 1990s, radionavigation methods such as Loran-C and GPS both looked promising,
and as costs declined, the technologies became more attractive. In the early 1990s, a few
transit agencies deployed Loran-C aided with dead-reckoning sensors. Loran-C was not
accurate enough and was soon abandoned. As GPS became operational and GPS
receivers were miniaturized and decreased in price, it became the sensor of choice.
Today, most new systems use DGPS technology. Additional research into driver
assistance systems and other applications continues. Some promising technologies
include automated docking and arrival annunciation.
4-7
4.2.6 NASA
NASA is conducting R&D in a number of GPS application areas in the space,
aeronautics, and terrestrial environments. These efforts include:
Space Applications: The emphasis in the space applications R&D of GPS is primarily in
three areas:
• Satellite Navigation: Use of GPS receivers onboard satellites to provide spacecraft
positioning and navigation data. Research in this area primarily involves
development of new software programmable receivers and the autonomous
navigation software that can be used for autonomous operation of science
satellites. This includes development of techniques for use of GPS for
autonomous satellite positioning above the GPS constellation out to Geo-
synchronous Earth Orbit (GEO) and above.
• Satellite Precise Positioning: Use of GPS receivers on research satellites for
precise positioning in support of onboard science instruments. The goal of this
research is to provide precise satellite positioning at the 10 cm level in real time.
The ability to perform at this level will enable numerous scientific measurements
not available today to support research in areas such as oceanography and
mapping. In order to demonstrate the ability to achieve this level of precision,
NASA is currently developing the TDRSS Augmentation Service Satellites
(TASS) to disseminate the GDGPS real-time differential correction message to
Earth satellites, and enable precise autonomous orbit determination, science
processing, and planning operations in Earth orbit. The TASS signal will be
transmitted on S-band from NASA’s TDRSS satellite, and will also provide a
ranging signal synchronized with GPS.
• GPS as a Science Instrument: Use of GPS signals for science observations will be
the subject of continuing research. Examples of this research are the use of GPS
signals for atmospheric research using occultation measurements through the
Earth’s atmosphere, and observations of GPS signals reflected off of the Earth’s
surface.
The latest generation of NASA GPS spaceborne receivers will be software programmable
units that will include the capability to receive the second civil signal. NASA has already
started to work on adding the second civil frequency capability to this receiver and plans
to begin flight tests on the capability as GPS satellites with the second civil signal
become available.
Aeronautics Applications: NASA will continue to use GPS receivers aboard NASA
aircraft for both aeronautics research and in support of airborne scientific observations.
There are numerous projects throughout NASA where GPS technology is being
developed for these purposes. Airborne GPS receivers have been used to support NASA
scientific research in areas such as Airborne Synthetic Aperture Radar (AIRSAR) and in
Greenland ice sheet thickness measurements.
NASA is also experimenting with using GPS in a “windowless cockpit” application
where GPS positioning is used together with a detailed three-dimensional map of the
Earth to provide synthetic vision for the crew in control of future high-speed vehicles.
4-8
This same technique may also be used in commercial aviation as an important safety aid
to avoid controlled flight into terrain accidents.
Terrestrial Applications: NASA is supporting the continued development of the IGS.
The data received from this network of GPS monitoring stations are providing data
products on a daily basis that are distributed via the Internet for users worldwide. One of
the direct products of the IGS is measurement of Earth crustal movement at the
centimeter per year level. In addition, a possible byproduct of this research could be the
eventual development of reliable techniques to be used for earthquake early warning and
prediction.
NASA has developed a high accuracy GPS augmentation system to support the
demanding real-time positioning, timing, and orbit determination requirements of its
science mission. GDGPS enables 10-20 cm real-time positioning accuracy for users with
dual-frequency GPS receivers. Very high end-to-end reliability is enabled through a
redundant architecture. Data from the GDGPS tracking network is made available to the
public on an hourly basis through the data archiving services of NASA.
Launch Range Architecture: Space-based navigation, GPS, and space-based range
(SBR) safety technologies are key components of the next generation launch and test
range architecture being developed by NASA with assistance from DoD and the FAA. A
space-based range would provide a more cost-effective launch and range safety
infrastructure while augmenting range flexibility, safety, and operability to better
accommodate more diverse and dispersed (multiple launch ranges) space operations in
the future. Development projects are underway using GPS-based tracking as a primary
means of launch vehicle tracking and surveillance.
Also in the future, reusable launch vehicles (RLV) are expected to be included in the mix
of aviation and space traffic. Full access to space from any of the spaceports that RLVs
might use requires compatible launch and telemetry tracking and control (TT&C)
systems, which are not locked into one or two geographic locations with fixed radars.
This implies the development of a cost-effective space-based range and TT&C
infrastructure, with global coverage. The future Space and Air Traffic Management
System (SATMS) network under development for aviation and space provides a long-
term answer for the full spectrum of coverage and control that is needed. A working
concept of operations for SATMS has been developed.
Other research and development work is also underway for future generations of vehicles
to transition to GPS-based guidance, navigation, and autonomous flight termination
systems.
4-9
4.2.7 NOAA
NOAA performs GPS research and development aimed at (1) improved GPS orbit
determination, (2) improved determination of the vertical coordinate using GPS, and (3)
development of models of error sources that can improve the accuracy attainable using
data from the national CORS network of GPS reference stations. Some of the specific
studies being undertaken are: improved modeling of tidal deformations of the Earth;
development of models of antenna phase center variation as a function of elevation angle
of a satellite; development of models of station specific multipath errors; and
development of improved models of geoid height required to convert GPS derived
ellipsoid heights to orthometric heights.
NOAA is also developing operational methods of using GPS derived total precipitable
water vapor determinations to improve the accuracy of weather forecasts. Studies are
underway to improve the methods used to position and orient aircraft performing
photogrammetry in support of nautical and aeronautical charting, as well as the
positioning of the keel of vessels relative to sea bottom hydrography. The National Polar-
orbiting Operational Environmental Satellite System (NPOESS) relies on a GPS
occultation sensor to monitor ionospheric electron density profiles and scintillation
properties.
NOAA is collaborating with academia in research toward achieving better than 1 cm real-
time positioning. Through dual-frequency carrier phase positioning methods, and real-
time CORS data (supporting both differential GPS and improved atmospheric models),
investigations are underway to achieve 1 cm or better in accuracy over CONUS as close
to real time as possible.
4-10
augmentation, potentially reducing long-term ownership costs. The first GPS III launch is
projected for 2013.
4-11
4-12
Appendix A
Definitions
A-1
to provide usable service within the specified coverage area. Signal availability is the
percentage of time that navigation signals transmitted from external sources are available
for use. Availability is a function of both the physical characteristics of the environment
and the technical capabilities of the transmitter facilities.
Coastal Confluence Zone (CCZ) - Harbor entrance to 50 nautical miles offshore or the
edge of the continental shelf (100 fathom curve), whichever is greater.
Common-use Systems - Systems used by both civil and military sectors.
Conterminous U.S. (CONUS) - Forty-eight adjoining states and the District of
Columbia.
Continuity - The continuity of a system is the ability of the total system (comprising all
elements necessary to maintain aircraft position within the defined airspace) to perform
its function without interruption during the intended operation. More specifically,
continuity is the probability that the specified system performance will be maintained for
the duration of a phase of operation, presuming that the system was available at the
beginning of that phase of operation.
Coordinated Universal Time (UTC) - UTC, an atomic time scale, is the basis for civil
time. It is occasionally adjusted by one-second increments to ensure that the difference
between the uniform time scale, defined by atomic clocks, does not differ from the
earth’s rotation by more than 0.9 seconds.
COSMIC – The Constellation Observing System for Meteorology, Ionosphere and
Climate is scheduled for launch in December 2005 and consists of six microsatellites
each carrying three instruments: a GPS radio occultation receiver, an ionospheric
photometer, and a tri-band beacon. These satellites will initially be placed in an initial
orbit 400 km above the Earth and over the first year will be gradually boosted to a final
orbit approximately 700 km above the Earth. During this time geodetic gravity
experiments will be conducted.
Coverage - The coverage provided by a radionavigation system is that surface area or
space volume in which the signals are adequate to permit the user to determine position
to a specified level of accuracy. Coverage is influenced by system geometry, signal
power levels, receiver sensitivity, atmospheric noise conditions, and other factors which
affect signal availability.
Differential - A technique used to improve radionavigation system accuracy by
determining positioning error at a known location and subsequently transmitting the
determined error, or corrective factors, to users of the same radionavigation system,
operating in the same area.
En Route - A phase of navigation covering operations between a point of departure and
termination of a mission. For airborne missions the en route phase of navigation has two
subcategories, en route domestic and en route oceanic.
Full Operational Capability (FOC) - A system dependent state that occurs when the
particular system is able to provide all of the services for which it was designed.
A-2
Global Navigation Satellite System (GNSS) – GNSS refers collectively to the world-
wide positioning, navigation, and timing (PNT) determination capability available from
one or more satellite constellations, such as the United States’ Global Positioning System
(GPS) and the Russian Federation’s Global Navigation Satellite System (GLONASS).
Each GNSS system employs a constellation of satellites operating in conjunction with a
network of ground stations.
GRACE – The Gravity Recover and Climate Experiment consists of two identical
satellites launched in March 2002 and flying approximately 220 km apart in a polar orbit
500 km above the Earth. Its primary mission is to conduct gravity field measurements.
Each spacecraft carries a Blackjack GPS receiver which, in addition, acquires GPS
occultation measurements.
Initial Operational Capability (IOC) - A system dependent state that occurs when the
particular system is able to provide a predetermined subset of the services for which it
was designed.
Integrity - Integrity is the measure of the trust that can be placed in the correctness of the
information supplied by a navigation system. Integrity includes the ability of the system
to provide timely warnings to users when the system should not be used for navigation.
Interference (electromagnetic) - Any electromagnetic disturbance that interrupts,
obstructs, or otherwise degrades or limits the performance of user equipment.
Jamming (electromagnetic) - The deliberate radiation, reradiation, or reflection of
electromagnetic energy for the purpose of preventing or reducing the effective use of a
signal.
Jason – An oceanography satellite launched December 2001 and flying in a 66° inclined
orbit 1300 km above the Earth. Its mission is to monitor global ocean circulation, study
the ties between the oceans and atmosphere, improved global climate forecasts and
predictions, and monitor events such as El Nino conditions and ocean eddies. It is
designed to directly measure climate change through very precise millimeter-per-year
measurements or global sea-level changes. On-board instrumentation includes a GPS
receiver and a laser retoreflector.
Multipath - The propagation phenomenon that results in signals reaching the receiving
antenna by two or more paths. When two or more signals arrive simultaneously, wave
interference results. The received signal fades if the wave interference is time varying or
if one of the terminals is in motion.
Nanosecond (ns) - One billionth of a second.
National Airspace System (NAS) - The NAS includes U.S. airspace; air navigation
facilities, equipment and services; airports or landing areas; aeronautical charts and
digital navigation data; information and service; rules, regulations and procedures;
technical information; and labor and material used to control and/or manage flight
activities in airspace under the jurisdiction of the U.S. System components shared jointly
with the military are included.
A-3
Navigation - The process of planning, recording, and controlling the movement of a craft
or vehicle from one place to another.
NAVTEX – A system designated by IMO as the primary means for transmitting coastal
urgent marine safety information to ships worldwide. The NAVTEX system broadcasts
Marine Safety Information such as Radio Navigational Warnings, Storm/Gale Warnings,
Meteorological Forecasts, Piracy Warnings, and Distress Alerts. Full details of the system
can be found in IMO Publication IMO-951E – The NAVTEX Manual.
Nonprecision Approach (NPA) – An instrument approach procedure based on a lateral
path and no vertical guide path. The procedure is flown with a navigation system that
provides lateral (but not vertical) path deviation guidance.
Precise Time - A time requirement accurate to within 10 milliseconds.
Precision Approach – An instrument approach procedure, based on a lateral path and a
vertical glide path, that meets specific requirements established for vertical navigation
performance and airport infrastructure.
Radiodetermination - The determination of position, or the obtaining of information
relating to positions, by means of the propagation properties of radio waves.
Radiolocation - Radiodetermination used for purposes other than those of
radionavigation.
Radionavigation - The determination of position, or the obtaining of information relating
to position, for the purposes of navigation by means of the propagation properties of
radio waves.
Reliability – The probability of performing a specified function without failure under
given conditions for a specified period of time.
Required Navigation Performance (RNP) - A statement of the navigation performance
accuracy necessary for operation within a defined airspace, including the operating
parameters of the navigation systems used within that airspace.
Surveillance - The observation of an area or space for the purpose of determining the
position and movements of craft or vehicles in that area or space.
Surveying - The act of making observations to determine the size and shape, the absolute
and/or relative position of points on, above, or below the Earth’s surface, the length and
direction of a line, the Earth’s gravity field, length of the day, etc.
Terminal - A phase of navigation covering operations required to initiate or terminate a
planned mission or function at appropriate facilities. For airborne missions, the terminal
phase is used to describe airspace in which approach control service or airport traffic
control service is provided.
Terminal Area - A general term used to describe airspace in which approach control
service or airport traffic control service is provided.
A-4
World Geodetic System (WGS) - A consistent set of constants and parameters
describing the Earth’s geometric and physical size and shape, gravity potential and field,
and theoretical normal gravity.
A-5
Appendix B
Glossary
The following is a listing of abbreviations for organization names and technical terms
used in this plan:
ABAS Aircraft Based Augmentation System
ADS-B Automatic Dependent Surveillance-Broadcast
AIRSAR Airborne Synthetic Aperture Radar
AIS Automatic Identification Systems
ARNS Aeronautical Radionavigation Service
C/A Coarse/Acquisition
CFR Code of Federal Regulations
CJCS Chairman, Joint Chiefs of Staff
cm centimeter
CONUS Conterminous United States
CORS Continuously Operating Reference Stations
COSMIC Constellation Observing System for Meteorology, Ionosphere and
Climate
CRAF Civil Reserve Air Fleet
B-1
DGPS Differential Global Positioning System
DHS Department of Homeland Security
DME Distance Measuring Equipment
DOC Department of Commerce
DoD Department of Defense
DOT Department of Transportation
ECDIS Electronic Chart Display Information System
FAA Federal Aviation Administration
FCC Federal Communications Commission
FHWA Federal Highway Administration
FMCSA Federal Motor Carrier Safety Administration
FOC Full Operational Capability
FRA Federal Railroad Administration
FRP Federal Radionavigation Plan
FRS Federal Radionavigation Systems
FTA Federal Transit Administration
GBAS Ground-Based Augmentation Systems
GDGPS Global Differential GPS
GEO Geosynchronous Earth Orbit
GLONASS Global Navigation Satellite System (Russian Federation System)
GLS GNSS Landing System
GNSS Global Navigation Satellite System
GPS Global Positioning System
GRACE Gravity Recovery and Climate Experiment
HA-NDGPS High Accuracy Nationwide Differential Global Positioning System
HEA Harbor Entrance and Approach
Hz Hertz (cycles per second)
IALA International Association of Marine Aids to Navigation and
Lighthouse Authorities
B-2
ICAO International Civil Aviation Organization
IFR Instrument Flight Rules
IGEB Interagency GPS Executive Board
IGS International GNSS Service
ILS Instrument Landing System
IMO International Maritime Organization
INMARSAT International Maritime Satellite Organization
INS Inertial Navigation System
INU Inertial Navigation Units
IOC Initial Operational Capability
IRAC Interdepartment Radio Advisory Committee
ITS Intelligent Transportation Systems
ITS-JPO Intelligent Transportation Systems Joint Program Office
ITU International Telecommunication Union
IVI Intelligent Vehicle Initiative
Jason See Appendix A
JPALS Joint Precision Approach and Landing System
JPL Jet Propulsion Laboratory
JPO Joint Program Office
km kilometer
LAAS Local Area Augmentation System
LGF LAAS Ground Facility
LNAV Lateral Navigation
LPV Localizer Performance with Vertical Guidance
m meter
MARAD Maritime Administration
MDGPS Maritime Differential GPS Service
MHz Megahertz
M-Code Military Code
B-3
MLS Microwave Landing System
MOA Memorandum of Agreement
MON Minimum Operational Network
NAS National Airspace System
NASA National Aeronautics and Space Administration
NATO North Atlantic Treaty Organization
Navaids Navigation Aids
NAVTEX See Appendix A
Navwar Navigation Warfare
NDB Nondirectional Beacon
NDGPS Nationwide Differential Global Positioning Service
NEXCOM Next Generation Air/Ground Communications
NGA National Geospatial-Intelligence Agency
NGS National Geodetic Survey
NHTSA National Highway Traffic Safety Administration
NII Networks and Information Integration
NIS Navigation Information Service
NOAA National Oceanic and Atmospheric Administration
NOTAM Notice to Airmen
NPA Nonprecision Approach
NPOESS National Polar-Orbiting Operational Environmental Satellite
System
NSF National Science Foundation
NTIA National Telecommunications and Information Administration
NTSB National Transportation Safety Board
OOBE Out-of-Band Emissions
OST Office of the Secretary of Transportation
OST/P Assistant Secretary for Transportation Policy
PNT Positioning, Navigation, and Timing
B-4
PPS Precise Positioning Service
PTC Positive Train Control
QZSS Quasi Zenith Satellite System
R&D Research & Development
RFI Radio Frequency Interference
RITA Research and Innovative Technology Administration
RLS Radiolocation Service
RLV Reusable Launch Vehicle
RNAV Area Navigation
RNP Required Navigation Performance
RNS Radionavigation Service
RNSS Radionavigation Satellite Service
RTCM Radio Technical Commission for Maritime Services
SA Selective Availability
SARPs Standards and Recommended Practices
SATMS Space and Air Traffic Management System
Satnav Satellite-Based Navigation
SBAS Satellite-Based Augmentation System
SBR Space-Based Range
SDD System Design and Development
SLSDC Saint Lawrence Seaway Development Corporation
SPS Standard Positioning Service
TACAN Tactical Air Navigation
TASS TDRSS Augmentation Service Satellites
TDRSS Tracking and Data Relay Satellite System
TT&C Telemetry Tracking and Control
UN United Nations
UNAVCO University NAVSTAR Consortium
U.S.C. United States Code
B-5
USCG United States Coast Guard
USNO United States Naval Observatory
UTC Coordinated Universal Time
VHF Very High Frequency
VOR Very High Frequency Omnidirectional Range
VORTAC Collocated VOR and TACAN
WAAS Wide Area Augmentation System
WGS World Geodetic System 1984
WRC World Radiocommunication Conference
B-6
References
R-1
R-2
Form Approved
REPORT DOCUMENTATION PAGE OMB No. 0704-0188
Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,
gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this
collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis
Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.
1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE & DATES COVERED
December 2005 Final Report
January 2002 – December 2005
4. TITLE AND SUBTITLE 5. FUNDING NUMBERS
2005 Federal Radionavigation Plan
OP0J/AD670
6. AUTHOR(S)
The FRP is updated biennially. This twelfth edition describes respective areas of authority and responsibility, and provides a management
structure by which the individual operating agencies will define and meet requirements in a cost-effective manner. Moreover, this edition
contains the current policy on the radionavigation systems mix. The constantly changing radionavigation user profile and rapid
advancements in systems technology require that the FRP remain as dynamic as the issues it addresses. This edition of the FRP builds on
the foundation laid by previous editions and further develops national plans towards providing an optimum mix of radionavigation
systems for the foreseeable future.
17. SECURITY CLASSIFICATION 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. LIMITATION OF
OF REPORT OF THIS PAGE OF ABSTRACT ABSTRACT