The Satcom airline satellite communication system used for two way ground to air, and air to ground passenger communication, has been extended to cover satellite navigation for aircraft. The system, developed by the Honeywell Inc-Racal Electronics Inc joint venture, is claimed to cut journey times on long-haul flights by up to an hour, by enabling air traffic controllers to track aircraft to within a couple of metres. This means they can map out precise flight paths for planes and cram more aircraft into the same airspace. Under the current navigation systems, planes fly 10 minutes behind each other, with 60 miles separating them laterally and 2,000 feet separating them vertically. This is because the current systems are not precise enough to allow them to fly any closer together safely. Once 200 miles offshore, aircraft lose direct contact with air traffic control computer systems and then rely on radar signals to maintain their flight path. This means that pilots are forced to fly routes dictated by the physical location of the radar installations so that they can pick up the signals and this is often not the most direct route. Satellites, however, do not pose these distance limitations so pilots can plan the most direct flight path and the Honeywell/Racal system enables flight controllers to pinpoint where an aircraft is accurately. Automatic Dependence Surveillance, as the system is called, does this by taking information from an aircraft’s flight management system, which is transmitted via satellite, to the air traffic control centre at the plane’s point of departure. The system was first tested on a British Airways Plc 747 flight last week.
Aeronautical Telecommunications Network
It uses database software developed by Honeywell, which already supplies flight management systems to British Airways and KLM Royal Dutch Airlines. The system displays the aeroplane’s route plan and all other information concerning the aircraft – its flight, such as engine data and weather conditions. The software extracts this information, holds it in a separate database and then transmits it, via satellite, to personal computers in the flight control centre. Air controllers define the information they need to monitor and navigate the aircraft, and how often this information should be flashed on the screens of their computers. For example, an aircraft’s position and vertical speed could flash on control tower screens every five minutes, whereas meteorological and engine data may only need to be reported every 10 minutes. Users can define up to 44 fields on which the database software will search, and can also define specific parameters within those fields. If the data is not within those parameters, the air traffic controller is alerted. If, for example, an aircraft suddenly loses height, this will be notified to the control tower. Now that Honeywell’s navigation system is up and running, Racal believes it is time to develop an Aeronautical Telecommunications Network – an industry standard network that will enable all satellite navigation systems to talk to each other. However for an infrastructure to be useful, all airlines need to implement a satellite navigation system and the air traffic control systems on the ground need to be updated. This is not likely to happen until 1998, said Racal. There is also a much larger debate within the avionics industry as to where the satellite system should be. Honeywell, which stands to lose out to Racal, which is also developing a similar system, believes it should become part of the flight management system within an aircraft. Others think it should be packaged as a separate box. Racal said its navigation system will be ready by August and will be tested by British Airways and Royal Dutch Airlines. The debate over where the system will reside and how it will interface to other navigation systems will be settled by the Airline Electronics Engineering Committee within the year, said Racal. The European Community is keen to back Automatic Dependence Surveillance and has given the F
rench and British Civil Aviation Authorities ú1m to install satellite navigation systems in more aircraft and also work on communications infrastructure to connect control centres in France with those in the UK. British Airways, KLM, Lufthansa and Air France will benefit from the funding. – Krishna Roy
