Vortices/Wing Tip Vortices
Vortices (wingtip vortices or wake vortices) are rotating masses of air generated at the wingtips of aircraft in flight as the higher-pressure air below the wing spills upward around the wingtip into the lower-pressure air above. They trail behind and below the flight path of the generating aircraft and represent a serious hazard to following aircraft.
Why Vortices Form
The pressure differential between the upper and lower surfaces of a lifting wing causes air to flow around the wingtips from below to above. This creates two counter-rotating vortices — one at each wingtip — rotating inward toward each other at the top. The vortex cores contain high rotational velocities and significant downwash.
Vortex Hazard
A light aircraft encountering the vortex of a heavy aircraft can lose control. The rotational velocity in the vortex core can exceed the roll control authority of a light aircraft, causing an uncontrollable roll. The vortices descend at approximately 400–500 ft/min and drift downwind — the danger zone is below and behind the generating aircraft’s flight path.
Wake Turbulence Avoidance
- Stay above the flight path of large preceding aircraft
- Land beyond the touchdown point of the preceding heavy aircraft
- Depart before the rotation point of the preceding heavy aircraft
- ATC provides mandatory wake turbulence separation — know the standards
- Wind is your friend — a crosswind will displace one vortex away from the runway; the upwind vortex moves toward the runway
On the TC Written Exam
Wake turbulence and vortex avoidance are regularly tested. Know: vortices form behind any lifting wing; heaviest aircraft create strongest vortices; vortices sink and drift downwind; light aircraft are most vulnerable.
Related Terms
See also: Wake Turbulence, Landing Sequence.