Death-spiral Definition

(aviation) The downward, corkscrew-motion of a disabled aircraft which is unrecoverably headed for a crash.

(pairs figure skating) A manoeuvre in which a male skater spins in place while holding one hand of his female skating partner as she circles around him with one skate on the ice and one leg extended outward parallel to the ice surface, all the while slowly lowering herself until her back almost touches the ice surface.

(idiomatic, by extension) The situation or course of action of one who is on a path toward some sort of inevitable catastrophic failure.