What is wake vortex encounter?

Question

What is wake vortex encounter?

Answer 1

More an aviation question but no matter...

All planes in flight tend to create a wake behind them which is turbulent and/or rolling air. One such component of the wake generated by aircraft is that a rolling cone of air tends to form at the wingtips leaving behind a spiralling vortex. This is caused, as Clavius correctly notes, by different airflow patterns above and below the wing. (Aircraft with highly swept back wings are more prone to this as well.)

This vortex is normally invisible but in fact can be seen in the right weather conditions, especially when planes come into land, I've seen this many a time when the air is cool and damp.

Within a few plane lengths the vortex starts dissipate a little but can stretch back for several miles behind the aircraft. Any plane, the lighter the plane the worse it is, that flies into this vortex will be subject to turbulent air, in some cases so violent the aircraft can be flipped over. It has in a few cases caused crashes. And the larger the plane, the more wake it will tend to create.

For this reason, and a few others, aircraft are usually separated by varying distances to reduce the chance of a wavortextex encounter.

Answer 2

A wake vortex is a strong, invisible swirl of air that extends rearward from the tips of the wings of airplanes.  The wake vortex of large airplanes like airliners is very strong and can cause pilots of light aircraft to lose control if they fly through them.  A wake vortex encounter is just such a flight.

The wake vortex is caused by the basic principles of lift.  Greater pressure under the wing and lower pressure above the wing causes the air above the wingtip to trend inboard and the air below the wingtip to trend outboard.  This shear creates the vortext.  Winglets help mitigate the vortex by actually converting some of it to effective thrust.