Vortex ring state

Definition

• A transient condition of downward flight (descending through air after just previously being accelerated downward by the rotor) during which an appreciable portion of the main rotor system is being forced to operate at angles of attack above maximum. Blade stall starts near the hub and progresses outward as the rate of descent increases.

References

• Helicopter Flying Handbook, Federal Aviation Administration, 2019
• Rotorcraft Flying Handbook, Federal Aviation Administration, 2000