Buffeting is a vibration of the aircraft that may appear during maneuvers at cruising speed.
It can be
1)Flying at critical angle of attack. As the angle of attack increases, the airflow over the wing starts to separate. This creates turbulence that causes the tailplane to shake. This is a warning to the pilot that a stall is imminent.
2)Flying faster than critical Mach number. Air flowing over the wing accelerates. When the airflow reaches the speed of sound, shock waves form and create disturbances which are felt as buffeting.
3)Use of speed brakes and flaps, especially at high speed.
4)Damage to the airplane that disturbs the airflow. For example, loss of a panel can create a turbulent airflow.
