Glossary of Terms
CONTENTS
Terms Database
Here is a list of commonly used terms one might encounter when dealing with GPS RAIM. This is not an exhaustive list, but it should provide answers to most of the questions people have pertaining to this website. For a more complete list, visit the FAA's acronym database.
AC90-100A is an advisory circular (AC) which provides operational and airworthiness guidance for operating on U.S. Area Navigation (RNAV) routes, Instrument Departure Procedures (DPs), and Standard Terminal Arrivals (STARs). Operators and pilots should use the guidance in the AC to determine their eligibility for these U.S. RNAV routes and procedures. See the most recent version of the AC90-100A here.
The Aeronautical Fixed Telecommunication Network (AFTN) is a worldwide system of aeronautical fixed circuits provided, as part of the aeronautical fixed service, for the exchange of messages and/or digital data between aeronautical fixed stations having the same or compatible communications characteristics. AFTN comprises aviation entities including: ANS (Air Navigation Services) providers, aviation service providers, airport authorities and government agencies, to name a few. It exchanges vital information for aircraft operations such as distress messages, urgency messages, flight safety messages, meteorological messages, flight regularity messages and aeronautical administrative messages.
Baro-aiding is a method of augmenting the GPS integrity solution by using a nonsatellite input source. Before checking RAIM prediction with this feature selected, check your operating manual. To ensure baro-aiding is available, the current altimeter setting must be entered into the receiver as described in the operating manual. Baro-aiding is not equivalent to advisory vertical navigation (VNAV).
The Federal Aviation Administration (FAA) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of civil aviation in the U.S. The Federal Aviation Act of 1958 created the group under the name "Federal Aviation Agency", and adopted its current name in 1967 when it became a part of the United States Department of Transportation.
The Federal Aviation Administration's major roles include:
- Regulating U.S. commercial space transportation
- Regulating air navigation facilities' geometry and Flight inspection standards
- Encouraging and developing civil aeronautics, including new aviation technology
- Issuing, suspending, or revoking pilot certificates
- Regulating civil aviation to promote safety, especially through local offices called Flight Standards District Offices
- Developing and operating a system of air traffic control and navigation for both civil and military aircraft
- Researching and developing the National Airspace System and civil aeronautics
- Developing and carrying out programs to control aircraft noise and other environmental effects of civil aviation
GPS (Global Positioning System) is a space-based global radionavigation system which is operated by the U.S. Air Force. Two GPS services are provided. The Precise Positioning Service (PPS) provides full system accuracy primarily to U.S. and allied military users. The Standard Positioning Service (SPS) provides an accurate positioning capability for civil users throughout the world. The GPS has three major segments: space, control, and user.
The GPS Space Segment is composed of 24 satellites in six orbital planes. The satellites operate in circular 20,200 km (10,900 nm) orbits at an inclination angle of 55 degrees and with approximately a 12-hour period. A minimum of four satellites must be visible to a user in order to compute a three-dimensional position solution.
The GPS Control Segment has five monitor stations and three ground antennas with uplink capabilities. The monitor stations track all satellites in view. The information from the monitor stations is processed at the Master Control Station (MCS) to determine satellite clock and orbit states and to update the navigation message of each satellite. This updated information is transmitted to the satellites via the ground antennas.
The International Civil Aviation Organization (ICAO), an agency of the United Nations, codifies the principles and techniques of international air navigation and fosters the planning and development of international air transport to ensure safe and orderly growth. Its headquarters are located in the Quartier International of Montreal, Canada.
The ICAO Council adopts standards and recommended practices concerning air navigation, its infrastructure, Flight inspection, prevention of unlawful interference, and facilitation of border-crossing procedures for international civil aviation. In addition, the ICAO defines the protocols for air accident investigation followed by transport safety authorities in countries signatory to the Convention on International Civil Aviation, commonly known as the Chicago Convention.
In communications and electronics, especially in telecommunications, interference is anything which alters, modifies, or disrupts a signal as it travels along a channel between a source and a receiver. The term typically refers to the addition of unwanted signals to a useful signal.
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. Java applications are typically compiled to bytecode (class file) that can run on any Java virtual machine (JVM) regardless of computer architecture.
Our GPS RAIM Grid Display Tool uses JAVA technology to acquire and display data on a webpage. To test if JAVA is running properly on your machine, visit our Java test page.
JavaScript is a scripting language used to enable programmatic access to objects within other applications. It is primarily used in the form of client-side JavaScript for the development of dynamic websites. JavaScript is a dialect of the ECMAScript standard and is characterized as a dynamic, weakly typed, prototype-based language with first-class functions. JavaScript was influenced by many languages and was designed to look like Java, but to be easier for non-programmers to work with.
A common misconception is that JavaScript is similar or closely related to Java; this is not so. Both have a C-like syntax, are object-oriented, are typically sandboxed and are widely used in client-side Web applications, but the similarities end there. JavaScript is otherwise a completely different language than JAVA, and has completely different requirements to run. It is also important to note that Javascript is supported by virtually all browsers, and while JAVA is not significantly less supported, it requires software to be installed on the users computer to work (JAVA runtime files) and requires consistent updating by the end-user in order to work with the latest JAVA technologies. Because of this, it is less frequently used than JavaScript, which is used on virtually every website in the world.
NOTAM or NoTAM is the quasi-acronym for a "Notice To Airmen". NOTAMs are created and transmitted by government agencies under guidelines specified by Annex 15: Aeronautical Information Services of the Convention on International Civil Aviation. A NOTAM is filed with an aviation authority to alert aircraft pilots of any hazards en route or at a specific location. The authority in turn provides means of disseminating relevant NOTAMs to pilots.
NOTAMs are issued (and reported) for a number of reasons, such as:
- hazards such as air-shows, parachute jumps, kite flying, rocket launches, etc.
- flights by important people such as heads of state (sometimes referred to as Temporary Flight Restrictions, TFRs)
- closed runways
- inoperable radio navigational aids
- military exercises with resulting airspace restrictions
- inoperable lights on tall obstructions
- temporary erection of obstacles near airfields (e.g. cranes)
- passage of flocks of birds through airspace (a NOTAM in this category is known as a BIRDTAM)
- notifications of runway/taxiway/apron status with respect to snow, ice and standing water (a SNOWTAM)
- notification of runway/taxiway/apron status with respect to volcanic ash or other dust contamination (an ASHTAM)
- software code risk announcements with associated patches to reduce specific vulnerabilities
Aviation authorities typically exchange NOTAMs over AFTN circuits.
An outage is a area where GPS interference has been detected or predicted to occur. See interference.
The integrity of a navigation system is a measure of its ability to provide a timely warning when the system fails to meet its stated accuracy and should no longer be used. The GPS systems itself can not provide integrity monitoring which satisfies aviation requirements. Integrity monitoring within certified aviation receivers is currently provided by Receiver Autonomous Integrity Monitoring (RAIM). RAIM is a method which examines the internal consistency of a set of redundant measurements, within the GPS receiver, to detect, and perhaps remove, a faulty measurement. In the case of GPS, this amounts to detecting, and perhaps removing, a faulty satellite from the set used navigation. When GPS is used as a supplemental navigation system, fault detection is all that is required. When GPS is used as a primary means of navigation, both fault detection and fault exclusion (FDE) is required.
Area Navigation (RNAV) is a method of air navigation that allows an aircraft to choose any course within a network of navigation beacons, rather than navigating directly to and from the beacons. This can conserve flight distance, reduce congestion, and allow instrument flight plans into airports without beacons.
A standard which GPS recievers must meet in order to be approved as the primary navigation aid for IFR operations.
The John A. Volpe National Transportation Systems Center or simply Volpe Center in Cambridge, Massachusetts, is a center of transportation and logistics expertise, operating under the United States Department of Transportation. For more information, visit their website at http://www.volpe.dot.gov/.
XML (eXtensible Markup Language) is a general-purpose specification for creating custom markup languages. For more imformation, see XML web service page.