Understanding Wake Turbulence and How to Avoid It

Wake turbulence is one of the most common flightpaths.
disturbances. Most pilots experience it on a regularUncommanded aircraft movements are the greatest
basis. In short, wake turbulence is the result of wakeindicators that an airplane is experiencing wake
vortices that are created whenever an airfoilturbulence. Because the onset of wake turbulence is
produces lift. Lift results from a pressure differentialoften surprisingly subtle, there have been many fatal
at the wing surfaces, with the lowest pressureinstances where pilots attempted a landing during mild
occurring above the wings and the highest pressureturbulence only to experience severe turbulence as
occurring beneath them. The pressure differentialthey neared the runway. When a pilot suspects that
then causes a rollup of the airflow behind the wings,wake is affecting his or her aircraft upon landing, the
which results in a swirling air mass that occurssafest move is to execute a go-around or a missed
downstream of the wingtips. The air mass rotatesapproach in order to prepare for stronger wake
counterclockwise at the right wing and clockwise atturbulence on the re-approach.
the left wing.With that said, there are ways to insure that wake
Slow flying, heavy aircraft produce the strongestturbulence is avoided in the first place. Starting with
wake, but short wing aircraft, due to their shorttakeoff, departing a few minutes later than your
wings, are the most prone to experiencing a varietyscheduled departure time if another aircraft
of wake turbulence situations, the most dangerousimmediately preceded you is a smart idea, especially
of which is an induced roll and yaw. Because the piloton a windy day. Then, once you depart, avoid
has little altitude for recovery, induced roll and yaw iscrossing behind and below the preceding plane.
particularly dangerous during take off and landing.Instead, try to climb above the plane's flight path or
During takeoff and landing, vortices push toward thedeviate slightly upwind from its path. If you have no
ground and move away from the runway when thechoice but to cross behind and below its path,
wind is low. But moderate to high wind keeps upwindattempt the pass at 1000 feet or more below its
the vortex in vicinity of the runway, which can causeflight path. When landing, make sure that your
the down wind vortex to push an aircraft intotouchdown point is well ahead of a preceding
neighboring runway paths. When an aircraft reachesaircraft's touchdown point, and always land well
altitude, vortices stabilize at between 500 and 900before an outgoing aircraft reaches its rotation point.
feet beneath its flight level. Until then, however, pilotsIf you're landing behind another aircraft on a crossing
must make certain to avoid drifting into other flightapproach, be sure to cross above its flight path.