# Property Trigger

A trigger based on a variable such as speed or altitude. You use a trigger value to determine when it fires.

### Attributes

<table data-header-hidden data-full-width="false"><thead><tr><th width="109.99993896484375">Attribute</th><th>Description</th></tr></thead><tbody><tr><td><strong>Active On Start</strong></td><td><strong>Enabled:</strong> the trigger will start evaluating the trigger conditions as soon as the missions starts<br><strong>Disabled:</strong> you need to activate this trigger during the mission</td></tr><tr><td><strong>Fire Once</strong></td><td><strong>Enabled:</strong> the trigger will deactivate (stop evaluating) when it fires a connection for the first time<br><strong>Disabled:</strong> the trigger will keep firing the connected events until it is deactivated</td></tr><tr><td><strong>Property Type</strong></td><td><p>You can select which property / variable to monitor:</p><ul><li>Altitude (Altitude above sea level, feet)</li><li>Altitude Above Ground (feet)</li><li>Speed (Indicated airspeed, knots)</li><li>Ground Speed (<a data-footnote-ref href="#user-content-fn-1">Surface relative</a> ground speed, knots)</li><li>Vertical Speed (knots)</li><li>Heading (True heading, degrees)</li><li>Pitch (degrees, pitch nose down is positive)</li><li>Bank (degrees, bank left is positive)</li><li>Latitude (decimal degrees)</li><li>Longitude (decimal degrees)</li></ul></td></tr><tr><td><strong>Trigger Value</strong></td><td>Value to base the trigger on. By choosing the <em>Higher, Equals, or Lower</em> action, you set the trigger.</td></tr><tr><td><strong>Minimum Duration</strong></td><td>Optional: Minimum time (seconds) that the trigger must be active before it can fire</td></tr><tr><td><strong>Duration Must Be Continuous</strong></td><td><strong>Enabled:</strong> the minimum duration must be reached in one continuous period.<br><strong>Disabled:</strong> separate periods are added together until the total duration is met.</td></tr></tbody></table>

### Actions

<table data-header-hidden><thead><tr><th width="110">Action</th><th>Description</th></tr></thead><tbody><tr><td><strong>Activate</strong></td><td>The trigger start evaluating the trigger conditions</td></tr><tr><td><strong>Deactivate</strong></td><td>The trigger will stop evaluating the trigger conditions</td></tr></tbody></table>

### Events

The events are only fired when the trigger is active

<table data-header-hidden><thead><tr><th width="109.99993896484375">Event</th><th>Description</th></tr></thead><tbody><tr><td><strong>Higher</strong></td><td>Fires when the property value is higher than the <em>trigger value</em></td></tr><tr><td><strong>Equals</strong></td><td>Fires when the property value equals the <em>trigger value</em>. <br><br>Also fires when the value crosses the <em>trigger value</em> (for example, if the value goes from 98 to 103, it will also 'equal' 100)</td></tr><tr><td><strong>Lower</strong></td><td>Fires when the property value is lower than the <em>trigger value</em></td></tr></tbody></table>

## See also

* For more advanced logic, use a [Custom Code](/miltech-mission-hub/developer-sdk/advanced-map-objects/custom-code.md) object.

[^1]: If stationary on a moving ship, the surface relative speed is 0


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