Skip to content
PilotSchool Knowledge Base

Understanding Vortex Location and Avoidance

Introduction to Wake Turbulence

Wake turbulence is a critical aerodynamic phenomenon caused by the generation of vortices at the wingtips of an aircraft as it generates lift. This turbulence can pose significant risks to following aircraft, especially during the critical phases of flight such as take-off and landing.

Characteristics and Location of Vortices

Formation and Fundamental Properties

  • Vortex Creation: Vortices are formed from the pressure difference between the upper and lower surfaces of an aircraft’s wings. This difference causes air to move from below the wing to above it, creating swirling masses of air.
  • Flow Direction: The left-wing vortex rotates clockwise, while the right-wing vortex rotates counter-clockwise.

Vortex Behavior in Different Flight Phases

Cruise Flight

  • Location in Still Air: Vortices generated during cruise flight descend between 300 and 900 feet, spreading laterally up to 5 miles behind the aircraft.
  • Risk Factor: At cruising altitudes, vortices are less hazardous due to established separation standards and greater aircraft speed.

Take-Off

  • Vortex Generation: Vortices are strong at the rotation point due to high angles of attack during initial climb.
  • Avoidance: Aircraft should rotate prior to the rotation point of a preceding larger aircraft and climb above its flight path to minimize risk.

Landing

  • Vortex Formation: Vortices continue from the approach until touchdown and may rebound to altitudes twice the aircraft’s wingspan.
  • Avoidance Strategy: Aircraft should maintain altitude above the preceding plane’s flight path and aim to touch down beyond their landing point.

Avoiding Wake Turbulence

Take-Off and Landing Profiles

  • Take-Off:
    • Rotate before the rotation point of the preceding aircraft.
    • Climb above its flight path.
    • Adjust lateral path to stay upwind of the vortices.
  • Landing:
    • Maintain a higher approach than the preceding aircraft.
    • Land beyond the preceding aircraft’s touchdown point.

Safety Tips and Recommendations

  • Separation: Adhere to prescribed separation distances of 3 to 6 NM depending on aircraft weight classes (heavy, medium, light).
  • Wind Considerations: Vortices drift with the wind; consider crosswind impacts on vortex position.
  • Waiting Strategy: For additional safety, a waiting time of 3 minutes before take-off can help ensure vortices dissipate.

Special Considerations

Helicopter Wake Turbulence

Despite their smaller size compared to fixed-wing aircraft, helicopters can generate potent vortices, especially at lower speeds in the range of 20-50 knots. Additional caution should be exercised when operating near helicopters.

Conclusion

Understanding wake turbulence and applying strategic avoidance measures are essential for ensuring aviation safety. Adhering to recommended take-off and landing profiles, and maintaining appropriate distances, significantly mitigate the risks associated with vortex-induced turbulence.

Additional Resources