Refers to a round rather than rectangular device used by paraglider
pilots to desend
safely when then existing rectangular wing, and therefore steerable wing, has been compromised to the degree that death or serious injury is eminent.
If a paraglider pilot determines that existing wing
they must throw a reserve parachute to arrest their descent or risk death or injury. One drawback, parachutes are unsteerable, if you happen to be flying over a Redwood
forest, or some 500,000 volt power lines, Mt Everest, you can imagine the sinking feeling?...