Spin is a phenomenon characterised by an almost vertical fall of the aircraft accompanied by a rotational movement. It can occur when the aircraft flies at low speed and high incidence.

Ground testing (vertical wind tunnel ) and flight testing are conducted to identify the spin modes to which the aircraft may be subjected and the flight control manoeuvres required to exit from spin. The instructions for stopping spin are then given in the aircraft flight manual .

If there is no simple, rapid way of recovering from a spin, the aircraft design is modified until satisfactory results are obtained.