Story ID: 354
Dispelling Common Misconceptions on Vortex Ring
By: AIN Staff
Caption: Canada's helicopter training manual distinguishes between vortex ring and other situations.
Word Count: 249
The Canadian Helicopter Flight Training Manuel (TP 9982 Exercise 26), published in 2006, makes a distinction between vortex ring state and settling with power, stating: “There are some uninformed pilots who use ‘settling with power’ to describe vortex ring, in fact, some publications use the terms interchangeably. Confusion results when symptoms are related that do not describe true vortex ring, but rather describe ‘settling with insufficient power.’ This may occur when a pilot attempts to arrest a rapid, low power descent only to find that he has insufficient power available to bring the helicopter to either a hover or a no-hover landing without exceeding the engine limits. However, this is not a vortex ring situation.”

The manual points to another situation, "over-pitching," which is often misinterpreted as vortex ring. “This is where the pilot rapidly increases collective considerably and the engine cannot produce enough power to overcome the large, swift increase in drag on the rotor system,” the Canadian document said. “The result is that the rotor system quickly slows down and loses efficiency causing the helicopter instantly to sink. Again, this is not vortex ring.”

Most common situations where operators are most likely to encounter vortex ring usually involve misjudging the wind with a heavy load on a hot day, the manual adds. “Downwind approaches to a confined area, or a mountain pad, are two good examples. Always control your rate of descent carefully on these occasions, and make sure an escape route is available.”