Definition
A linked pair of aerodynamic events in which the wing first exceeds its critical angle of attack and loses lift (the stall), and then, if one wing is more stalled than the other and yaw is present, the airplane departs into an autorotative descent with the wings held at high angle of attack (the spin). The spin cannot occur without the stall; the stall must come first.
Plain English
It's two problems in sequence. First the wings stop flying because they're tilted into the air too steeply. Then, if the airplane is also yawing or skidding when that happens, it can roll over and start corkscrewing toward the ground. Fix the first problem and the second one can't happen.
Context Anchor
Seen in stall training, slow-flight discussions, traffic pattern safety, and recovery procedures for loss of control at low airspeed.
Derivation
Stall originally meant to stop or come to a standstill. In aviation, it does not mean the airplane stops moving; it means the wing’s smooth lifting airflow has stopped working normally. Spin comes from the ordinary idea of rotating, but in aviation it specifically means a stalled airplane rotating downward.
Why Pilots Care
An unrecovered spin from a stall leads to rapid altitude loss and is a leading cause of fatal accidents in the traffic pattern and during maneuvering flight.
Grounding Statement
The key picture is a wing losing normal lift, followed by the airplane rotating downward if the stall is not kept straight and controlled.
Intuition Check
A stall is not an engine quitting; it is a wing airflow problem. A spin is not just a normal turn; it is a rotating descent that happens after a stall.
Example Sentence 1
Most stall and spin accidents happen in the pattern, where pilots are low, slow, and distracted by the turn from base to final.
Example Sentence 2
During a power-off stall in the practice area, the instructor demonstrated how a slight wing drop can quickly develop into a spin if left uncorrected.