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Route manager: Difference between revisions
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A real route-manager page! | A real route-manager page! | ||
==Introduction== | == Introduction == | ||
(in the following sections, familiarity with basic IFR concepts, [[Autopilot]] usage and radio navigation is assumed) | (in the following sections, familiarity with basic IFR concepts, [[Autopilot]] usage and radio navigation is assumed) | ||
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It's important to realize that the route-manager (and [[GPS]]) are pieces that a panel instrument might present as a single real world device - the mapping between C++ modules, generic user interface and in-panel instruments is very fluid, by design. In general core features exist in whichever place seems the most natural, and it's up to instruments to aggregate the core modules as they require. | It's important to realize that the route-manager (and [[GPS]]) are pieces that a panel instrument might present as a single real world device - the mapping between C++ modules, generic user interface and in-panel instruments is very fluid, by design. In general core features exist in whichever place seems the most natural, and it's up to instruments to aggregate the core modules as they require. | ||
==Concepts== | == Concepts == | ||
The route-manager maintains a flight-plan, consisting of departure, destination, alternate airport and cruise information, as well as a list of waypoints. All information is currently optional, which is highly unrealistic, but convenient. | The route-manager maintains a flight-plan, consisting of departure, destination, alternate airport and cruise information, as well as a list of waypoints. All information is currently optional, which is highly unrealistic, but convenient. | ||
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An important piece of terminology is a ''leg'', which is a section of route between two waypoints. Many real-world devices deal in legs primarily, since each leg corresponds to a desired track, a distance and possibly an altitude to climb / descend. In the FlightGear route manager, the ''active leg'' is from the previous waypoint to the current waypoint - i.e the current waypoint is where you're heading to at the moment. | An important piece of terminology is a ''leg'', which is a section of route between two waypoints. Many real-world devices deal in legs primarily, since each leg corresponds to a desired track, a distance and possibly an altitude to climb / descend. In the FlightGear route manager, the ''active leg'' is from the previous waypoint to the current waypoint - i.e the current waypoint is where you're heading to at the moment. | ||
==Defining a Route== | == Defining a Route == | ||
The simplest way to define a route is to add waypoints one at a time by identifier. Since navaid identifiers are not unique, the route-manager uses your departure airport or the previously defined waypoint to locate the identifier search. In practice, navaids with conflicting names are located far enough apart that this works automatically in practice. | The simplest way to define a route is to add waypoints one at a time by identifier. Since navaid identifiers are not unique, the route-manager uses your departure airport or the previously defined waypoint to locate the identifier search. In practice, navaids with conflicting names are located far enough apart that this works automatically in practice. | ||
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See also [[#Useful Software]] | See also [[#Useful Software]] | ||
==Activating a Route== | == Activating a Route == | ||
Activating a route performs certain checks, and creates start and end waypoints based on the selected departure and arrival info. For the moment, that consists of adding the departure runway as waypoint zero, but in the future (when departure procedures are supported) this will create the appropriate | Activating a route performs certain checks, and creates start and end waypoints based on the selected departure and arrival info. For the moment, that consists of adding the departure runway as waypoint zero, but in the future (when departure procedures are supported) this will create the appropriate procedure waypoints. | ||
This will also be the hook point for calculating cruise information, such as top-of-climb and top-of-descent points in the future. | This will also be the hook point for calculating cruise information, such as top-of-climb and top-of-descent points in the future. | ||
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Other devices (especially a GPS/FMS) may trigger other changes based on activating a route, such as sequencing the first leg of the route, resetting internal counters / timers, and so on. | Other devices (especially a GPS/FMS) may trigger other changes based on activating a route, such as sequencing the first leg of the route, resetting internal counters / timers, and so on. | ||
==Flying a Route== | == Flying a Route == | ||
When a route is activated, the GPS system enters 'leg' mode, and will automatically sequence waypoints as they are overflown. Note that all aircraft can use the default route-manager and GPS functions, even aircraft that would never (historically) has such systems. This is a convenience to casual users, testing, and so on. | When a route is activated, the GPS system enters 'leg' mode, and will automatically sequence waypoints as they are overflown. Note that all aircraft can use the default route-manager and GPS functions, even aircraft that would never (historically) has such systems. This is a convenience to casual users, testing, and so on. | ||
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In aircraft with realistic navigation systems, or customised autopilots, the default behaviours above may not work; hopefully the aircraft author has provided alternative methods, such as panel instruments, to control the interaction with that aircraft's autopilot and panel. | In aircraft with realistic navigation systems, or customised autopilots, the default behaviours above may not work; hopefully the aircraft author has provided alternative methods, such as panel instruments, to control the interaction with that aircraft's autopilot and panel. | ||
===Lining up with Runways=== | === Lining up with Runways === | ||
The route-manager only provides guidance to a particular location - to arrive on a particular heading, such as lined up with a runway or ILS localizer, it is necessary to use multiple waypoints. Virtually all ILS approaches define multiple fixes that can be used for this purpose, usually including altitude restrictions. For example, for the [http://flightaware.com/resources/airport/KPHX/IAP/ILS+OR+LOC+RWY+08 KPHX 08 approach], waypoints ALLIS, SARTE, HIKID, ILIKE, JAMIL and WAZUP are defined, extending 20nm from the threshold. Typically you enter the initial approach fix (IAF), ALLIS in this example, and as many of the intermediate waypoints as necessary, depending on required descent profile. It is helpful to include the glidepath capture waypoint (WAZUP), to provide an easy altitude reference and cross-check that your ILS receiver is working. | The route-manager only provides guidance to a particular location - to arrive on a particular heading, such as lined up with a runway or ILS localizer, it is necessary to use multiple waypoints. Virtually all ILS approaches define multiple fixes that can be used for this purpose, usually including altitude restrictions. For example, for the [http://flightaware.com/resources/airport/KPHX/IAP/ILS+OR+LOC+RWY+08 KPHX 08 approach], waypoints ALLIS, SARTE, HIKID, ILIKE, JAMIL and WAZUP are defined, extending 20nm from the threshold. Typically you enter the initial approach fix (IAF), ALLIS in this example, and as many of the intermediate waypoints as necessary, depending on required descent profile. It is helpful to include the glidepath capture waypoint (WAZUP), to provide an easy altitude reference and cross-check that your ILS receiver is working. | ||
==Properties== | == Properties == | ||
When a route is active, the route-manage provides various pieces of information based upon current aircraft position / speed, and the route progress. These values would be calculated by the navigation computer in a real system, but are handled by route-manage in FG for convenience. Values logged include the takeoff time, estimated time enroute (ETE), distance remaining enroute, and so on - browse the property tree to see what's available. | When a route is active, the route-manage provides various pieces of information based upon current aircraft position / speed, and the route progress. These values would be calculated by the navigation computer in a real system, but are handled by route-manage in FG for convenience. Values logged include the takeoff time, estimated time enroute (ETE), distance remaining enroute, and so on - browse the property tree to see what's available. | ||
= Useful Software = | = Useful Software = | ||
To easily create entries for route manager the application [http://rubyforge.org/projects/fgmap | To easily create entries for route manager the application [http://rubyforge.org/projects/fgmap Flightgear Mapping] is useful. With just a few clicks you can add navaids displayed on the map and aswell a route you have defined there via waypoints. Navaids can be inserted into the list at any point, not just at the end. | ||
= Further Reading = | = Further Reading = | ||
For additional details please see [[Route manager internals]]. | For additional details please see [[Route manager internals]]. | ||