This maneuver might just safe your life!
Vortex ring state occurs when a helicopter is drawn into its own downwash, and requires certain flight conditions. These include low forward speed (up to 10 knots for a low disc loading helicopter and up to 30 knots for a high disc loading helicopter); a relatively rapid rate of descent (at least 500 feet per minute for a low disc loading helicopter and up to 1,500 feet per minute for a high disk loading helicopter); and up to 40 percent torque (power setting)
Over 95 percent of vortex ring state accidents are pilot-induced. The remainder are caused by collapsing winds, loss of visual references, or performance problems. Most vortex accidents occur on the approach downwind
Pilots have traditionally been trained to recover from the vortex ring state by lowering the collective and pushing forward on the cyclic. The problem is that due to the tailwind, they are following their vortex ring, and the ground usually meets them before they leave the vortex ring state!
After a fateful encounter with vortex ring state one day in 1987, Claude Vuichard, a highly experienced Swiss pilot, resolved to find a better way to exit the vortex ring state. As a flight instructor, he resolved to put the helicopter into a vortex and put the technique to the test.
Reasoning that the tail rotor continues to work normally in the vortex ring state, he thought he could use it to help reach the upwind part of the vortex to the side of the aircraft. Then supported with cyclic, the helicopter would reach the upwind part of the vortex very fast. He tried it at the next opportunity, and found it worked not only on the SA315B Lama which he was flying, but it also worked on all of the 20 different helicopter types he have flown.
It’s a very straightforward maneuver. As soon as you find yourself in a vortex ring state, you immediately pull up the collective to provide maximum available power, apply counter torque with the pedal to maintain your heading, and push the cyclic in the opposite direction for a 15- to 20-degree bank. For a counter-clockwise main rotor system, you should bank to the right; while a clockwise-turning main rotor system requires a left bank to exit.
The whole maneuver should be done in two seconds. You should reach the required bank of 15 degrees after the first second, and the helicopter should be level again a second later. As soon as the rotor reaches the upwind part of the vortex, the recovery is complete. The average height loss during the recovery procedure is 20 to 50 feet, depending on the duration of the maneuver.
There are a lot of operational situations where the traditional recovery technique just doesn’t work. These include when you’re on final approach with a tailwind; when you have obstacles in front; when you’re at low height over the ground; when you’re hovering out of ground effect, and the updraft collapses; during many hoist operations; and during many underslung operations.
Claude Vuichard's technique works in all operational conditions, even to prevent entering vortex ring state in collapsing up winds.
Claude believe that it should be trained until it becomes a reflex. As soon as a pilot in slow forward flight and/or hover out of ground effect feels lightness in the seat ( normally 0.3 to 0.8 G) they should immediately and reflexively apply the Claude Vuichard recovery technique to prevent an accident.
The technique was included in the FAA’s updated Helicopter Flying Handbook, published in October 2019. It presents the Vuichard Recovery as “the quickest exit from the hazard” of vortex ring state, explaining the technique along with common errors.
Flight schools around the world are now teaching the Vuichard Recovery and we hope that soon most flight schools will teach this as the main/only maneuver.
Information taken from the very insightful article Claude Vuichard & Tim Tucker tell the story behind the Vuichard Technique - Vertical Mag. By sharing the information, we hope we can save someone's life out there!