A Descent performance model is comprised of two or more points that define the characteristics of the performance model. These points are displayed in a chart at the top of the display and defined in a table below. The Descent performance model allows you to define descent profile by time, distance, and fuel to climb to a given altitude, similar to how aircraft operating manuals are configured. This performance model is determined by the data entered without regard to aerodynamics, propulsion characteristics, or weight. Descent can be considered an altitude varying version of Basic Descent. Use this model if you know specific elements of an aircraft descent profile. To access the descent model,
- Open aircraft properties.
- Right click on "Descent.”
- Select new model type. This Descent model is “AGI Descent Model”.
Chart and Table
You can add new points by left-clicking in the profile to add a point at that specific location. You can also add a new point before the currently selected point by clicking Insert Item and defining the point in the window that appears. You can edit existing points by double-clicking any of their fields in the table or by clicking Edit Item ... to edit the currently selected point in a separate window; in addition, you can edit the altitude of a point by double-clicking it in the chart.
Click Remove Item to remove the currently selected point. A point that is displayed in red is an invalid entry - one which is not a monotonic increase of fuel consumption, time elapsed, and downrange distance over the previous entry. Click Remove Invalid Items to remove all points that are currently indicated as being invalid.
The fields that define each point in the model are described in the following table.
| Field | Description |
|---|---|
| Altitude | The aircraft's altitude in feet. You cannot specify an altitude below sea level (0). If a procedure is specified that requires the aircraft to fly below sea level, the performance models in effect at sea level will be applied to that procedure. |
| Downrange | The ground distance in nautical miles from the first point in the model to the aircraft's position at this point. |
| Elapsed Time | The amount of time that has elapsed since the first point of the model. |
| Segment Time | The amount of time that has elapsed since the previous point of the model. |
| Airspeed (TAS True Airspeed: the speed that the aircraft is moving relative to the airmass that it is flying in., CAS Calibrated Airspeed: the speed reported by the airspeed indicator, corrected for position and instrument error., EAS Equivalent Airspeed: the airspeed at sea level (International Standard Atmosphere) at which the dynamic pressure is equal to the dynamic pressure at the aircraft's current true airspeed and altitude., Mach The ratio of the aircraft's speed and the speed of sound at the aircraft's altitude, with local atmospheric conditions.) | Displays the calculated airspeed during this segment of the model. |
| Fuel | The amount of fuel required to climb from or descend to sea level for the associated altitude; this number must be a monotonic increase or decrease, respectively, from the previous entry. |
| Fuel Flow | The amount of fuel used in pounds per hour. |
Chart Commands
You can also interact with the chart using a right-click menu available within the actual chart display; this menu is defined in the table below.
Other Options
There are several other options available outside of the chart and table.