Route manager: Difference between revisions

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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 things.
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 things.
==Finding an Airport and Lining up with a Runway==
Route Manager is so simple to use that a player can simply input an airport code (e.g. KSFO) and select "true heading" under the autopilot heading control, and end up at the airport. Doing so will NOT line the pilot up with the runway, and will simply fly the plane over the airport. However, every waypoint name is unique; a player could be on the other side of the world, 5,000 miles away, and Route Manager would still lock onto the desired airport.
Those who wish to end up lined with the runway must considerably more work.
They must find out a waypoint that is directly in front of a runway, and then find out the runway's localizer. Since a localizer will not extend more than 20 miles, it is imperative to reach the waypoint first. When the player inputs the localizer frequency into their NAV1, it will direct them to the runway. For example, a waypoint near 28R of KSFO is MENLO (see the chart HERE[http://204.108.4.16/d-tpp/0912/00375BIGSUR.PDF]). When a player reached MENLO via Route Manager, they would follow the NAV1 Localizer. In this case, 28R's frequency is 111.7, as seen on the chart above. MENLO is far enough from 28R to keep turning. In real life, you could also follow the heading indicated (330 degrees) from MENLO. However, the waypoints in FlightGear are not always exactly on the spot, so this method is not desirable.
In essence, a player can follow route manager until within range of navaids- first the general airport frequency (KSFO, its 115.8), and then the localizer. 


==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.

Revision as of 18:39, 20 December 2009

A real route-manager page!

Introduction

(in the following sections, familiarity with basic IFR concepts, Autopilot usage and radio navigation is assumed)

The route-manager models part of the functionality found in real-world GPS and FMS devices, but is usable in any aircraft. Some panel instruments may provide access to the route manager via their own UI, but the route-manager is always available through a generic dialog box. The route-manager is also how a flight plan is made available to FlightGear - in the future this will hopefully permit better ATC and multi-player interactions, since ATC logic or controllers will be able to observe the filed plan associated with a pilot.

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

The route-manager maintains a flight-plan, consisting of departure, destination, alternate airport and cruise information, as well as a list of waypoints (technically, route segments, or legs). A flight plan must have a departure airport and destination airport specified; all other information is currently optional, which is highly unrealistic, but convenient.

Route manager waypoints are entered as a navaid ident, an explicit latitude/longitude pair, or as an offset (bearing and distance) from another navaid. Each waypoint may also have an altitude associated with it, for vertical navigation modes (VNAV). In the future, other data, especially speed restrictions, may also be associated with waypoints.

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.

Until departure and arrival procedures are supported, you can often define them yourself, by creating offset waypoints. The syntax is ident/radial/distance, for example TLA/347/13 defines a waypoint (which will be named 'TLA13') which is 13nm away from the TLA VOR on magnetic radial 347.

Routes can be loaded (and soon, saved) to a simple XML format, so you may prefer to create the routes in a text editor, and load them instead of entering them by hand. Support for flight-planning tools is also planned, contact the developer list if you are interested on working on such a feature.

In the future, auto-routing using airways or VOR-VOR routing will also be added.

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 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.

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

When a route is activated, the GPS system enters 'leg' mode, and will automatically sequence waypoints as they are overflow. 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.

In particular, the GPS drives some properties of the generic autopilot, so 'true heading hold' mode can be used to fly the route manager route (or any other GPS course).

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 things.

Finding an Airport and Lining up with a Runway

Route Manager is so simple to use that a player can simply input an airport code (e.g. KSFO) and select "true heading" under the autopilot heading control, and end up at the airport. Doing so will NOT line the pilot up with the runway, and will simply fly the plane over the airport. However, every waypoint name is unique; a player could be on the other side of the world, 5,000 miles away, and Route Manager would still lock onto the desired airport. Those who wish to end up lined with the runway must considerably more work. They must find out a waypoint that is directly in front of a runway, and then find out the runway's localizer. Since a localizer will not extend more than 20 miles, it is imperative to reach the waypoint first. When the player inputs the localizer frequency into their NAV1, it will direct them to the runway. For example, a waypoint near 28R of KSFO is MENLO (see the chart HERE[1]). When a player reached MENLO via Route Manager, they would follow the NAV1 Localizer. In this case, 28R's frequency is 111.7, as seen on the chart above. MENLO is far enough from 28R to keep turning. In real life, you could also follow the heading indicated (330 degrees) from MENLO. However, the waypoints in FlightGear are not always exactly on the spot, so this method is not desirable. In essence, a player can follow route manager until within range of navaids- first the general airport frequency (KSFO, its 115.8), and then the localizer.

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.