AS350 B3e course · Astar hazards
Vortex ring state
Descending into your own downwash
The essentials
In a steep, slow, powered descent, a helicopter can settle into the air it has just pushed down. The handbook's three conditions, together: descending at 300 ft/min or more, below effective translational lift, and using 20–100 % of available power.
In the ring, more power on its own makes things worse: the way out is to move the disc out of the ring. Airbus's guidance for its helicopters gives two ways — forward (the classic recovery) or sideways (Vuichard). The best recovery is not to enter it: watch steep, slow, downwind approaches.
Flying into your own downwash
In a steep, slow descent a helicopter can settle into the air it has just pushed down. Vortices at the blade tips grow into a ring that recirculates through the disc — and more power only makes the ring stronger.
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Build the ring
Vortex ring state and its three conditions. This diagram needs JavaScript.
Set the descent rate, airspeed and power. When all three conditions line up, the ring closes.
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The three conditions
The handbook's conditions, all at once:
- descending vertically or nearly so at 300 ft/min or more
- airspeed below effective translational lift
- using 20 to 100 percent of engine power.
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Inside the ring
A hovering rotor pushes air down. In a vertical descent, air comes up through the disc to meet it. At some descent rate the two roughly balance near the blade tips, and the tip vortices, instead of being carried away below, recirculate back into the disc.
Much of the rotor is then working in air it has already accelerated. Lift falls, the aircraft sinks faster, and the faster flow up through the disc feeds the ring further.
Settling with power
Older American material calls the same thing settling with power — the helicopter keeps settling even with plenty of power applied. Current FAA material uses vortex ring state.
Both names describe the descent you can't stop by pulling more collective. When an instructor or a report uses either term, check which they mean.
Recognising it
The early signs are vibration, a rate of descent higher than the power should give, and controls that feel less effective. A pilot who responds by raising the collective sees the descent rate increase.
That reversal — more power, more sink — is the signature.
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Two ways out
Airbus Helicopters' guidance (SIN 3463-S-00), written after EASA flight tests on the Squirrel, covers both techniques for all its types:
- Fully developed VRS: the classic recovery is effective — check, then increase the collective, and fly forward out of the ring.
- Early stages, or a developed ring when downwind or with obstacles ahead: the Vuichard recovery — power, lateral cyclic, pedals to hold heading.
This course follows the manufacturer. Your RFM and instructor confirm the technique for your aircraft and operation.
The classic recovery
Check the collective, then increase it while moving the cyclic forward to gain airspeed. The rotor flies out into clean air and translational lift returns.
The increase is the newer part. Older guidance, including the FAA handbook, says to lower the collective; the EASA tests found that increasing it lost less height. Expect height loss either way — in a developed ring it can be large, which is why the recovery has to start early.
The Vuichard recovery, for a clockwise rotor
Apply power and lateral cyclic towards the tail-rotor thrust, holding heading with the pedals. The added power raises tail-rotor thrust, the tilted disc and the tail rotor push the same way, and the rotor reaches clean air once its edge leaves the ring.
American rotors bank right with left pedal. On the Astar's clockwise rotor it is the mirror: bank about 15° left, with right pedal to hold heading. It needs power available. The EASA tests found it worked best in the early stages of VRS.
Where it happens
Steep approaches to confined areas and pinnacles, downwind approaches that need a high descent rate, hovering out of ground effect with a slow descent — long-line work, a hoist — and a slow, steep approach over a landing site to keep a load under control.
All of them are common in utility work.
Why downwind makes it worse
With a tailwind, a normal-looking approach over the ground is flown at a lower airspeed. To hit the same spot the aircraft has to come down more steeply, and it is below translational lift sooner.
That puts two of the three conditions in place before the pilot has done anything unusual. Add the power needed to slow down at the bottom and the third is there too.
Eyes down, descending slowly
Long-line and vertical-reference work put the pilot's eyes on the load, not the horizon. A slow descent out of ground effect is hard to judge from looking straight down, and the aircraft is already below translational lift with substantial power applied.
Watch the descent rate on purpose — glance at the vertical speed, pick a reference — rather than trusting the sense of sinking.
Which is NOT one of the three conditions for vortex ring state?
Vortex ring state needs power applied — a rotor using some of the engine's power. At idle (as in autorotation) the flow comes up through the disc instead.
Why doesn't more power get you out?
More power drives more air down into the same recirculating ring — the sink rate can get worse, not better.
For a clockwise rotor, which way does the Vuichard technique move the disc?
Towards the tail-rotor thrust — left in the Astar — with right pedal to hold heading. The mirror of American types.
Fully developed VRS, clear air ahead. Which recovery does Airbus's guidance say is effective?
The classic recovery, with the collective increased rather than lowered. Airbus keeps the Vuichard for the early stages, or a developed ring when downwind or with obstacles ahead.
What does the traditional recovery cost?
Flying forward out of the ring takes height — sometimes a lot.
Why does a tailwind approach raise the risk?
Over the same ground track, the aircraft is slower through the air and has to come down more steeply.
Sources
- Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 11, Helicopter Emergencies and Hazards
- Safety Information Notice 3463-S-00 Rev 2, Vortex ring state training and the Vuichard recovery technique · Airbus Helicopters · All Airbus Helicopters types; content as reported by Flight Safety Australia (Feb 2026)
- Deadly power of the ring · Flight Safety Australia · Brendan Reinhardt, 18 March 2026 (EASA VRS flight tests and Airbus SIN 3463-S-00)
- FAA recognizes Vuichard recovery in handbook · AIN · 22 January 2020
- Technique: Escape plan · AOPA Pilot · Markus Lavenson, 1 February 2020
- Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 10, Advanced Flight Maneuvers
Educational only. Not approved training material, and never a substitute for the Rotorcraft Flight Manual, an instructor, or your operator's procedures. Figures marked as manufacturer data or test results are not limitations. This content is a draft and has not yet been reviewed by an instructor.