Definition
A vibration or shaking felt through the airframe and controls as the airplane approaches an aerodynamic stall at low airspeed. It is caused by turbulent, separated airflow coming off the wing at high angles of attack and striking the tail and other downstream surfaces, serving as a natural warning that the wing is nearing the stall.
Plain English
A shaking the pilot feels when the airplane is flying so slowly that the wing is about to stop producing enough lift. The airflow over the wing becomes rough and bumpy, and that roughness shakes the tail and the controls.
Context Anchor
A pilot may feel slow-speed buffet during slow flight, stall practice, or an approach if the airplane is allowed to get too slow.
Derivation
Buffet comes from the Old French buffeter, meaning to strike or hit repeatedly. The word captures the feeling well: the airplane is being repeatedly struck by disturbed air, producing a shaking sensation the pilot can feel through the seat and controls.
Why Pilots Care
It acts as a natural warning of an approaching stall, giving the pilot time to lower the nose and add power before control is lost.
Intuition Check
Slow-speed buffet does not mean ordinary turbulence or engine roughness. It means shaking caused by disturbed airflow over the wing as the airplane gets close to a stall.
Example Sentence 1
As the airspeed bled off in the steep turn, the pilot felt the slow-speed buffet and immediately reduced back pressure to lower the angle of attack.
Example Sentence 2
The instructor used slow-speed buffet to show the student the first physical sign that the wing was about to stall.