When flying over areas with limited outlanding possibilities it is advantageous to take into account the available airfields and known outlanding options. When planning for such eventualities it is useful to think in terms of a decision height, at which point planning for a possible landing should take precedence over task completion considerations. It therefore follows that it is more useful to establish a range from an airfield at a specific decision height rather than examining the required height to reach landing options for any height, given that when flying with ample height, one will not be concerned with landing.
The airfield range annotation allows you to set a decision height for airfields and outlanding fields and then find the required ranges from these airfields, given specific sailplane performance and weather conditions.
To create an airfield range annotation, press the airfield range button in the map annotation toolbar.
You may then specify the following parameters:
You can then add an airfield or out-landing waypoint to the airfield range annotation by enabling the add airfield button and clicking on the corresponding waypoints on the screen. Please note that you can change the waypoints list displayed by using the Waypoint list selector on the top of the map panel at any time if you need to access way points stored in a different list.
If you would like to automatically select all the available fields, you can directly press the OK button. In this case, all airfields and off-field landings that are currently displayed on the screen will be selected. For this functionality to work, you must have previously selected no airfield.
You can also remove unwanted airfields from the annotation by activating the remove airfield button and then clicking on the unwanted selected waypoints.
For each selected airfield or out-landing field, an orange range ring will be displayed. This is the approximate range within which you should be able to make the selected airfield if you are at the decision height, according to the specified assumptions for glider performance and weather. Terrain obstructions are not taken into account. The assumptions for decision height and assumed LD are shown on the ring graphics.
Please note that it may be possible to reach the field from farther away, if you have additional altitude, or from within certain positions in the circle if you are lower than the decision height. The map panel view does not display options for all possible heights, but rather highlights your strategic options for a flight based on a chosen decision height to transit from crosscountry task considerations to planning a possible landing.
To view landing options for all points in a flight, you may activate the airfield range chart by pressing the button. For more information on the chart, see below. Contrary to the analysis page view, the chart will show the entire duration of the flight when activated in the map view.
By clicking on the Analysis tab you may view a chart showing airfield range of the flight for the selected landing options and assumptions.
The chart shows the glidescope (i.e. excess or extra-needed altitude) to the most favorable landing option according to the specified parameters set and among the selected airfields or out-landing fields for any point in the flight. The line above zero, market in green indicates that a field is reachable while the line below zero, traced in red indicates that there is no landing option among the selected.
Points in the flight where the glider is below decision height and there is no available landing option are highlighted with a red area while points where the glider is below decision-height but within reach are highlighted in green. In addition, at any time the glider is above the decision height inside a range circle, this is highlighted in orange.
The name of the closest airfield (not in distance but in required height) is noted in the chart. The point in flight at which there is a change of airfield is market with a light-blue vertical line.
Please note that the chart will display the flight segment chosen for the analysis. To change this, select the appropriate flight interval in the analysis page.