All aircraft in the X-Plane 12 world cast a wake turbulence – a wing cutting through the air in X-Plane 12 leaves a vortex in the air that swirls inward over the wingtip, and sinks slowly as it dissipates energy over time. The strength of the vortex and its lifetime depends on the lift force generated by the wing (i.e. a wing that has to lift a 172 does not create a strong vortex, whereas a wing that supports a 747 surely does). Over the course of its life, the vortex sinks slowly and is displaced by the prevailing wind.
Flying through such a vortex can be dangerous! If you cross the vortex left by an airliner while flying a 172 yourself, be prepared to be tossed around or even flipped upside down. If you do the same with roles reversed, you might see a slight bump just enough to ripple the surface of your coffee (be sure not to do this in an A350 as spilled coffee can cause in-flight engine shutdowns).
Wakes left by AI aircraft
AI aircraft in X-Plane run the full flight model. That is, each wing is calculated using the same methods and with the same accuracy as for the user aircraft. Thus the amount of energy left in the wake vortex is clearly known, it just comes from the flight model. Therefore, if ATC clears that 747 to take off before you, be sure to stay above their flight path until you can turn away from it. For landing, stay above the preceding planes path and touch down slightly further down the runway than they did to stay safe.
Wakes left by online traffic, live traffic, and other plugins
For aircraft that are not run by the X-Plane flight model, such as other players’ aircraft from an online network, or real-world traffic injected from a plugin like Live Traffic using data from an ADS-B exchange, X-Plane makes a best effort guess based on the data provided by the plugin. The plugin can tell X-Plane how heavy the aircraft is, and its wing area and wingspan. In the absence of this data, X-Plane will fall back on a fairly conservative light aircraft estimate, assuming a Learjet-sized aircraft weighing 10 tons with a 12m wingspan. This means you are not going to get flipped upside down in your 737 if you end up flying through a wake left by an old plugin. This is to minimize user frustration with existing online flying plugins. Since the wakes are technically an extension of the TCAS override API used by plugins since X-Plane 11.50, all plugins that show traffic in X-Plane 11.50 are compatible with wake turbulence generation and will gain that base functionality automatically when used in X-Plane 12.
Plugins can use new datarefs starting with X-Plane 12 to inform X-Plane of physical properties of the non-player aircraft that are then used for a more accurate strength and duration of the wake. By writing to the new datarefs, a plugin providing traffic data can upgrade from the “generic Learjet wake” to an accurate wake representative of the aircraft they are actually drawing.
Learn about wake turbulence avoidance
In X-Plane, you can cheat and make the wake left by an aircraft visible by having it drawn in the sky in a color scheme showing its danger (from red over orange and yellow down to green) so you can avoid it (or fly through it on purpose to experience the effect). Wake visualization is just one of the many graphical flight model outputs available. Press Ctrl+M to toggle graphical flight model output in X-Plane. By repeatedly pressing Ctrl-M you can cycle through all the visualizations available, while a small white label tells you what you are looking at. Keep toggling until you see “Wake Turbulence” displayed and marvel at the air disturbance waiting to make your day interesting.
You can also use X-Avion on your iPad to have wake turbulence danger zones visualized – this works in real airplanes using ADS-B data, and it works in X-Plane when driving X-Avion over network.