A stall occurs when the wing exceeds its critical angle of attack and airflow separates, causing a loss of lift. A spin is an aggravated stall in which one wing is more deeply stalled than the other, producing autorotation.
Load factor (G) is the ratio of the total lift to the airplane's weight: a load factor of 2 means the wings are supporting twice the aircraft's weight. In a level turn, load factor increases with bank angle:
Because stall speed increases with the square root of the load factor, a 60° banked level turn (2 G) raises stall speed by about 41%. This is the accelerated stall — stalling at a higher-than-normal airspeed because of increased load.
Heavier aircraft stall at higher speeds. The V-speeds on the airspeed indicator (the bottom of the white and green arcs) are published at maximum gross weight; at lighter weights the airplane stalls slower.
For a spin to develop, the airplane must be stalled AND yawed. The classic scenario is an uncoordinated, skidding turn from base to final at low altitude — a stall there can rapidly become a spin with insufficient altitude to recover.
The standard recovery is the PARE method:
Once rotation stops, neutralize the rudder and recover from the dive smoothly to avoid a secondary stall or overstress.
VA is the maximum speed at which full, abrupt control deflection won't structurally damage the airplane, because the wing will stall before it overstresses. VA decreases as weight decreases. Always slow to or below VA in turbulence.