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The introduction to this article provides insufficient context for those unfamiliar with the subject. Please help improve the article with a good introductory style. |
Future Air Navigation System (FANS) is a standard developed by the air transport industry to allow more aircraft to fit into a given volume of air space. A number of generations of FANS standards are covered by the single term, progressing from simple automations of current processes up to rather futuristic approaches.
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Background
Aircraft are operated using two major methods; Positive Control and Procedural Control. Positive Control is used in areas which have radar. The controller "sees" the airplanes in the control area and uses VHF voice to provide instructions to the flight crews to ensure separation. Because the position of the aircraft is updated frequently and VHF voice contact timely, separation standards (the distance one aircraft must be separated by another) is less. This is because the air traffic controller can recognize problems and issue corrective directions to multiple airplanes in a timely fashion. Separation standards are what determines the number of airplanes which can occupy a certain volume of airspace. Procedural Control is used in areas (such as oceanic and landmasses) which do not have radar. The FANS concept was developed to improve the safety and efficiency of airplanes operating under Procedural Control. This methods uses time-based procedures to keep aircraft separated. The separation standard is determined by the accuracy of the reported positions, frequency of position reports, and timeliness of communication with respect to intervention. Non-FANS procedural separation uses Inertial Navigation Systems for position, flight crew voice reports of position (and time of next waypoint), and High Frequency radio for communication. The INS systems have error introduced by drifting after initial alignment. This error can approach 10 nmi. HF radio communication involves contacting an HF operator who then transcribes the message and sends it to the appropriate ATC Service Provider. Responses from the ATC Service Provider go to the HF radio operator who contacts the airplane. The voice quality of the connection is often poor leading to repeated messages. The HF radio operator can also get saturated with request for communication. This leads to procedures which keeps airplanes separated by as much as 100 nmi laterally, 10 minutes in trail, and 4000ft altitude. These procedures reduce the number of airplanes which can operate in a given airspace. If marketing demand pushes airlines to operate at the same time on a given route, this can lead to airspace congestion; an issue which is handled by delaying departures or separating the airplanes by altitude. The latter can lead to very inefficient operation.
ATC using FANS
The FANS concept involves improvements to Communication Navigation and Surveillance.
Communication improvements
This involved a transition from voice communications to digital communications. Specifically ACARS was used as the communication medium. This allowed other application improvements. An application was hosted on the airplane known as Controller Pilot Data Link Communication (CPDLC). This allows the flight crew to select from a menu of standard ATC communications, send the message, and receive a response. A peer application exists on the ground for the Air Traffic Controller. They can select from a set of messages and send communications to the airplane. The flight crew will respond with a WILCO, STANDBY, or REJECT. The current standard for message delivery is under 60 seconds one way.
Navigation improvements
This involves a transition from Inertial Navigation to Satellite Navigation using the GPS satellites. This also introduced the concept of Actual Navigation Performance (ANP). Previously, flight crews would be notified of the system being used to calculate the position (radios, or inertial systems alone). Because of the deterministic nature of the GPS satellites (constellation geometry), the navigation systems can calculate the worst case error based on the number of satellites tuned and the geometry of those satellites. (Note: it can also characterize the potential errors in other navigation modes as well). So, the improvement not only provides the airplane with a much more accurate position, it also provides an alert to the flight crew should the actual navigation performance exceed the required navigation performance.
Surveillance improvements
This involves the transition from voice reports (based on inertial position) to automatic digital reports. The application is known as ADS-C (Automatic Dependent Surveillance - Contract). In this system, an Air Traffic Controller can set up a contract with the airplane navigational system to automatically send a position report on a specified periodic basis (such as every 5 minutes). The controller can also set up deviation contracts which would automatically send a position report if a certain lateral deviation was exceeded. This contracts are set up between ATC and the aircraft systems. The flight crew has no workload associated with this set up.
FANS procedural control
The improvements to CNS allow new procedures which reduce the separation standards for FANS controlled airspace. In the South Pacific, they are targeting 30/30 (this is 30 nmi lateral and 30 nmi in trail). This makes a huge difference in airspace capacity.
History
ICAO
The International Civil Aviation Organization (ICAO) first developed the high level concepts starting with the initiation of the Special Committee on Future Air Navigation Systems in 1984. The final report was released in 1991 with a plan released in 1993.
Pacific engineering trials
FANS as we know it today had its beginning in 1991 with the Pacific Engineering Trials (PET). During these trials, airplanes installed applications in their ACARS units which would automatically report positions. These trials demonstrated the potential benefits to the airlines and airspace managers.
Implementation
United, Cathay Pacific, QANTAS, and Air New Zealand approached the Boeing Company in 1993 and requested that Boeing support the development of a FANS capability for the 747-400. Boeing worked with the airline to develop a standard which would control the interface between FANS capable airplanes and air traffic service providers. The development of the FANS capable aircraft systems proceeded simultaneously with the ATC Ground System improvements necessary to make it work. These improvements were developed and certified (using a QANTAS airplane) on June 20, 1995. While these concepts originated with ICAO, the first implementations came from the jetliner manufacturers Boeing and Airbus. Boeing's implementation is called FANS-1 and Airbus's is called FANS-A. Airbus subsequently came out with some enhancments to FANS-A, to give FANS-A+. Both companies are working on a further evolution, namely Boeing on FANS-2 and Airbus on FANS-B. Various ground systems have been built, mainly by ATC organisations, to interoperate with FANS-1/A as the combination is known.
FANS interoperability team
The FANS Interoperability Team (FIT) was initiated in the South Pacific in 1998. The purpose of this team is to monitor the performance of the end-to-end system, identify problems, assign problems and assure they are solved. The members include airframe manufacturers, avionics suppliers, communication service providers, and air navigation service providers. Since this time, other regions have initiated FIT groups.
Milestones
A Qantas Airways, On June 20, 1995, Qantas B747-400 VH-OJQ became the first aircraft to certify Future Air Navigation System (FANS-1) by Remote Type Certification (RTC) in Sydney Australia. It was followed by the first commercial flight from Sydney to Los Angeles on June 21. QF certified the RR FANS-1 package, ANZ and UAL certified the GE and PW FANS-1 package respectively. B Boeing Business Jet, on May 24, 2004, completed the first North Atlantic flight by a business jet equipped with the Future Air Navigation System (FANS), a system that streamlines communication between airplane crews and air-traffic controllers. The airplane touched down at the European Business Aviation Convention and Exhibition in Geneva, Switzerland. The non-stop eight-hour, 4,000-nautical-mile flight originating from Gary/Chicago International Airport in Gary, Indiana, was part of a North Atlantic Traffic trial conducted by the FANS Central Monitoring Agency (FCMA).
External links
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