amorce de la vrille

CONT: L'amorce de la vrille peut être facilement décelée et une prompte intervention peut empêcher une vrille complète.

OBS: spin: An aerial maneuver or performance, either controlled or uncontrolled, in which an airplane makes a vertical descent with its nose pointed sharply or slightly downward, while revolving about the line of descent in any of various attitudes.
OBS: incipient: In the beginning stage; commencing; beginning to appear.