A tactical air navigation system, commonly referred to by the acronymTACAN, is a navigation system used by military aircraft. It provides the user with bearing and distance (slant-range or hypotenuse) to a ground or ship-borne station. It is a more accurate version of the VOR/DME system that provides bearing and range information for civil aviation. The DME portion of the TACAN system is available for civil use; at VORTAC facilities where a VOR is combined with a TACAN, civil aircraft can receive VOR/DME readings. Aircraft equipped with TACAN avionics can use this system for en route navigation as well as non-precision approaches to landing fields. The space shuttle is one such vehicle that was designed to use TACAN navigation but later upgraded with GPS as a replacement.[1]
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The typical TACAN onboard user panel has control switches for setting the channel (corresponding to the desired surface station's assigned frequency), the operation mode for either transmit/receive (T/R, to get both bearing and range) or receive only (REC, to get bearing but not range). Capability was later upgraded to include an air-to-air mode (A/A) where two airborne users can get relative slant-range information. Depending on the installation, Air-to-Air mode may provide range, closure (relative velocity of the other unit), and bearing,[2] though an air-to-air bearing is noticeably less precise than a ground-to-air bearing. A TACAN only equipped aircraft cannot receive bearing information from a VOR only station.
- The Future Air Navigation System (FANS) is an avionics system which provides direct data link communication between the pilot and the air traffic controller.The communications include air traffic control clearances, pilot requests and position reporting.
- Air Navigation Data has created a series of courses to train employees and qualify instrument procedure designers in all aspects of procedure design as well as the latest advances in instrument procedure design criteria. Continue Reading. With our specialized expertise, we can advise on almost any factor that affects instrument procedure design.
History[edit]
The TACAN navigation system is an evolution of radiotransponder navigation systems that date back to the British Oboe system of World War II. In the United States, many companies were involved with the development of TACAN for military aircraft. Hoffman Laboratories Div. of the Hoffman Electronics Corp.–Military Products Division[3] (now NavCom Defense Electronics)[4] was a leader in developing the present TACAN system in the US starting in the late 1950s.
Operation[edit]
TACAN in general can be described as the military version of the VOR/DME system. It operates in the frequency band 960-1215 MHz. The bearing unit of TACAN is more accurate than a standard VOR since it makes use of a two-frequency principle, with 15 Hz and 135 Hz components, and because UHF transmissions are less prone to signal bending than VHF.
The distance measurement component of TACAN operates with the same specifications as civil DMEs. Therefore, to reduce the number of required stations, TACAN stations are frequently co-located with VOR facilities. These co-located stations are known as VORTACs. This is a station composed of a VOR for civil bearing information and a TACAN for military bearing information and military/civil distance measuring information. The TACAN transponder performs the function of a DME without the need for a separate co-located DME. Because the rotation of the antenna creates a large portion of the azimuth (bearing) signal, if the antenna fails, the azimuth component is no longer available and the TACAN downgrades to a DME only mode.
Accuracy[edit]
Theoretically a TACAN should provide a 9-fold increase in accuracy compared to a VOR, but operational use has shown only an approximate 3-fold increase.[5]
Accuracy of the 135 Hz azimuth component is ±1° or ±63 m at 3.47 km.[6] Accuracy of the DME portion must be 926 m (0.500 nmi) or 3 percent of slant range distance, whichever is greater, per FAA 9840.1 1982.[6] and FAA N8200.121
TACAN stations can provide distance up to 390 nautical miles.[citation needed]
Modern TACANs are much more accurate. The requirement now is to have portable TACAN that is IFR certifiable, both station and portable systems. The latest modern version of TACAN has been tested and could be a feasible back-up to future Air traffic control systems and may even be integrated into systems for a seamless back up.[citation needed]
Past TACANs have relied on high output power (up to 10,000 watts) to ensure good signal in space to overcome nulls present in antenna design and to provide their required[citation needed] 200 mile range. With the advancement of technology, antenna design has improved with higher gain antennas, much shallower nulls, and lighter construction. Now it's feasible to have a 200 nmi range with a 400 watt TACAN DME transmitter, making the TACAN package much smaller, more portable and more reliable (a decrease in power also reduces heat, which lengthens the life of electronics).
On the first Space Shuttle flight, CapcomJoseph P. Allen reported up to the crew that their TACANs had locked onto the Channel 111 signals at St. Petersburg, FL at a range of 250 miles.
TACAN is getting smaller: full TACAN coverage can now be provided in a system that can be carried on a single trailer weighing less than 4000 lbs, and set up by two people in less than an hour. TACAN Transceivers can now be as small as lunch boxes (with full coverage and range) and the antennas can be reduced from 800 pounds to less than 100 pounds.[citation needed]
Benefits[edit]
Because the azimuth and range units are combined in one system it provides for simpler installation. Less space is required than a VOR because a VOR requires a large counterpoise and a fairly complex phased antenna system. A TACAN system theoretically might be placed on a building, a large truck, an airplane, or a ship, and be operational in a short period of time. An airborne TACAN receiver can be used in air-to-air mode, which allows two cooperating aircraft to find their relative bearings and distance.
Drawbacks[edit]
For military usage a primary drawback is lack of the ability to control emissions (EMCON) and stealth. Naval TACAN operations are designed so an aircraft can find the ship and land. There is no encryption involved, an enemy can simply use the range and bearing provided to attack a ship equipped with a TACAN. Some TACANs have the ability to employ a 'Demand Only' mode wherein they will only transmit when interrogated by an aircraft on-channel. It is likely that TACAN will be replaced with a differential GPS system similar to the Local Area Augmentation System called JPALS. The Joint Precision Approach and Landing System has a low probability of intercept to prevent enemy detection and an aircraft carrier version can be used for autoland operations.
Some systems used in the United States modulate the transmitted signal by using a 900 RPM rotating antenna. Since this antenna is fairly large and must rotate 24 hours a day, it can cause reliability issues. Modern systems have antennas that use electronic rotation (instead of mechanical rotation) with no moving parts.
Future[edit]
Like all other forms of ground-based aircraft radio navigation currently used, it is likely that TACAN will eventually be replaced by some form of space-based navigational system such as GPS.[7]
See also[edit]
- Battle of Lima Site 85 (SAC TACAN captured March 1968)
Air Navigation System
References[edit]
- ^Goodman, J.L.; Propst, C.A. (2008), 'Operational use of GPS navigation for space shuttle entry', Position, Location and Navigation Symposium, 2008 IEEE/ION (published May 2008): 731–743, doi:10.1109/PLANS.2008.4570031, hdl:2060/20080014095, ISBN978-1-4244-1536-6
- ^Rockwell International (July 7, 1992). 'Aircraft rendezvous using low data rate two-way TACAN bearing information'. Archived from the original on June 12, 2011.
- ^Missiles and Rockets, July 20, 1959, v. 5, no. 30, p. 127.
- ^http://www.navcom.com/ NavCom Defense Electronics
- ^Albert Helfrick (2009). 'Principle of avionics 5th edition' (book).Missing or empty
|url=(help) - ^ abDepartment of Transportation and Department of Defense (March 25, 2002). '2001 Federal Radionavigation Systems'(PDF). Retrieved November 27, 2005.
- ^Department of Transportation and Department of Defense (March 25, 2002). '2001 Federal Radionavigation Plan'(PDF). Retrieved August 2, 2006.
External links[edit]
| Wikimedia Commons has media related to Tactical Air Navigation. |
- dB Systems, Inc. - Manufacturer of mechanically scanned, electronically scanned, shipboard, man-portable, and tactical TACAN Antennas - Complete TACAN Antenna profile with datasheets and photos
- Rantec Microwave Systems - Manufacturer of non-rotating TACAN antennas - Complete with antenna internal photos and specs
- Moog Navigation and Surveillance Systems - Fixed site, shipboard, mobile and man-portable TACAN systems
- Leonardo Air Traffic Management - Fixed site TACAN systems
The Future Air Navigation System (FANS) is an avionics system which provides direct data link communication between the pilot and the air traffic controller. The communications include air traffic control clearances, pilot requests and position reporting.[1] In the FANS-B equipped Airbus A320 family aircraft, an Air Traffic Services Unit (ATSU) and a VHF Data Link radio (VDR3) in the avionics rack and two data link control and display units (DCDUs) in the cockpit enable the flight crew to read and answer the controller–pilot data link communications (CPDLC) messages received from the ground.[2]
Overview of FANS[edit]
The world's air traffic control system still uses components defined in the 1940s following the 1944 meeting in Chicago which launched the creation of the International Civil Aviation Organization (ICAO). This traditional ATC system uses analog radio systems for aircraft Communication, navigation and surveillance (CNS).
Air traffic control's ability to monitor aircraft was being rapidly outpaced by the growth of flight as a mode of travel. In an effort to improve aviation communication, navigation, surveillance, and air traffic management ICAO standards for a future system were created, this integrated system is known as the Future Air Navigation System (FANS) and allows controllers to play a more passive monitoring role through the use of increased automation and satellite based navigation.
In 1983, ICAO established the special committee on the Future Air Navigation System (FANS), charged with developing the operational concepts for the future of air traffic management (ATM). The FANS report was published in 1988 and laid the basis for the industry's future strategy for ATM through digital CNS using satellites and data links. Work then started on the development of the technical standards needed to realise the FANS Concept.
In the early 1990s, the Boeing Company announced a first generation FANS product known as FANS-1. This was based on the early ICAO technical work for automatic dependent surveillance (ADS) and controller–pilot data link communications (CPDLC), and implemented as a software package on the flight management computer of the Boeing 747-400. It used existing satellite based ACARS communications (Inmarsat 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 by which one aircraft must be separated from another) are 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 determine the number of airplanes which can occupy a certain volume of airspace.
Procedural control is used in areas (oceanic or land) which do not have radar. The FANS concept was developed to improve the safety and efficiency of airplanes operating under procedural control. This method 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 (19 km).
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 be saturated with requests for communication. This leads to procedures which keep airplanes separated by as much as 100 nmi (190 km) laterally, 10 minutes in trail, and 4,000 ft (1,200 m) in altitude. These procedures reduce the number of airplanes which can operate in a given airspace. If market demand pushes airlines to operate at the same time on a given route, this can lead to airspace congestion, which is handled by delaying departures or separating the airplanes by altitude. The latter can lead to very inefficient operation due to longer flying times and increased fuel burn.
ATC using FANS[edit]
The FANS concept involves improvements to Communication, navigation and surveillance (CNS).
Communication improvements[edit]
Air Navigation System
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 communications (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[edit]
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 not satisfy the required navigation performance (RNP).
Surveillance improvements[edit]
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' (software arrangement) with the airplane's navigational system, to automatically send a position report on a specified periodic basis – every 5 minutes, for example. The controller can also set up a deviation contract, which would automatically send a position report if a certain lateral deviation was exceeded. These contracts are set up between ATC and the aircraft's systems, so that the flight crew has no workload associated with set-up.
FANS procedural control[edit]
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 (56 km) lateral and 30 nmi (56 km) in trail). This makes a huge difference in airspace capacity.
History[edit]
ICAO[edit]
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 1983. The final report was released in 1991 with a plan released in 1993.
Pacific engineering trials[edit]
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[edit]
United Airlines, 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 airplane. Boeing worked with the airlines 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 certified (using a QANTAS airplane) on June 20, 1995.
Both Boeing and Airbus continue to further develop their FANS implementations, Boeing on FANS-2 and Airbus on FANS-B. In the interim, Airbus came out with some enhancements to FANS-A, now referred to as FANS-A+. Various ground systems have been built, mainly by ATC organizations, to interoperate with FANS-1/A.
FANS interoperability team[edit]
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.
Service providers[edit]
Customers that operate aircraft need to get their FANS 1/A capable aircraft connected to both the ATN (Aeronautical Telecommunication Network) and to the Iridium and/or Inmarsat Satellite network. Commercial aircraft operators typically get their long haul fleet connected and have dedicated personnel to monitor and maintain the satellite and ground link while business aircraft and military aircraft operators contact companies like AirSatOne to commission the system for the first time, conduct functionality testing and to provide ongoing support. AirSatOne provide advanced FANS 1/A services through their Flight Deck Connect[3] portfolio of products. Flight Deck Connect includes a connection to the Iridium and/or Inmarsat satellites for FANS 1/A (via Datalink), and Safety Voice Services,[4] along with ancillary services (AFIS/ACARS) such as weather information, engine/airframe health and fault reports.
Operational approval[edit]
Some of the more advanced service providers such as AirSatOne and ARINC offer FANS 1/A testing services. When an aircraft is outfitted with FANS 1/A equipment either through the Type Certificate or STC process the equipment must demonstrate compliance with AC 20-140B for operational approval. As an example AirSatOne offers testing through the satellite and ATN network to support FANS 1/A functionality in accordance with RTCA DO-258A/ED-100A and provides test reports to meet the requirements of RTCA DO-258A/ED-100A, RTCA DO-306/ED-122 and FAA Advisory Circular AC 20-140B.[5] AirSatOne also provides first time system commissioning on each aircraft, troubleshooting testing and pre-flight maintenance checks to test FANS 1/A functionality either monthly or prior to flight in the FANS environment.
Milestones[edit]
On June 20, 1995, a QantasB747-400 (VH-OJQ) became the first aircraft to certify the Rolls-Royce FANS-1 package by remote type certification (RTC) in Sydney, Australia. It was followed by the first commercial flight from Sydney to Los Angeles on June 21. Subsequently, Air New Zealand certified the General Electric FANS-1 package, and United Airlines certified the Pratt & Whitney FANS-1 package.
On May 24, 2004, a Boeing Business Jet completed the first North Atlantic flight by a business jet equipped with FANS. The airplane touched down at the European Business Aviation Convention and Exhibition (EBACE) in Geneva, Switzerland. The non-stop eight-hour, 4,000-nautical-mile (7,400 km) 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).
In August 2010, Aegean Airlines became the first airline to commit to upgrading its Airbus A320 fleet with a FANS-B+ retrofit system offered by Airbus.[6]
See also[edit]
- Aircraft Communications Addressing and Reporting System (ACARS)
- Aeronautical Telecommunication Network (ATN)
References[edit]
- ^An Assessment of Flight Crew Experiences with FANS-1 ATC Data Link
- ^de Cuendias, Sophie. 'The Future Air Navigation System, FANS B'. FAST 40. Airbus, an EADS Company (July, 2007): 13–19. ISSN1293-5476.
- ^'Flight Deck Connect™ by AirSatOne'. AirSatOne. Retrieved July 14, 2019.CS1 maint: discouraged parameter (link)
- ^'FAQ Inmarsat aircraft safety and communications' services'. Inmarsat. Retrieved July 14, 2019.CS1 maint: discouraged parameter (link)
- ^'AC 20-140B (Cancelled) - Guidelines for Design Approval of Aircraft Data Link Communication Systems Supporting Air Traffic Services (ATS) (Cancelled)'. Federal Aviation Administration. Retrieved July 14, 2019.CS1 maint: discouraged parameter (link)
- ^'Aegean commits to FANS-B+ upgrade for A320s'. ATW Online. August 16, 2010. Retrieved July 14, 2019.CS1 maint: discouraged parameter (link)
Air Navigation Order
External links[edit]
Air Navigation Order