---

---

---

In typical flight, the rotor disc directs the airflow downwards, creating lift. A vortex ring state (VRS), though, involves a toroid-shaped path of airflow circumscribing the blade disc, as the airflow moves down through the disc, then outward, and then down through the top again. This re-circulation of flow can negate much of the lifting force and cause a catastrophic loss of altitude.

"Vortex Ring State", also known as settling with power is a hazardous condition encountered in helicopter flight. It occurs when the helicopter has three things occurring; a rate of descent greater than 300 feet per minute, an airspeed slower than effective translational lift, and the helicopter is using more than 20% of its available power.A helicopter typically induces a vortex ring state by descending into its own downwash. This condition can be corrected by moving the cyclic forward, which controls the pitch angle of the rotor blade, slightly pitching nose down, and establishing forward flight. The aircraft will fly into "clean air", and will be able to regain lift.

A clear understanding of this condition is essential for helicopter pilots to avoid danger.

On a fast descent, no vortex will form because the vertical airspeed is faster than the recirculation speed - although rapid descent through one's own downwash is itself a highly dangerous maneuver.
With high airspeed, no vortex will form because the translational airflow is faster than the recirculation speed.

---