A flat spin.
A flat spin is a dangerous and potentially life-threatening flight condition that occurs when an aircraft enters an uncontrolled spinning motion.
A flat spin happens when the center of gravity shifts too far aft (toward the tail), and the aircraft’s rotation becomes more horizontal. In this situation, the wings aren’t producing enough lift, and the aircraft essentially falls out of the sky while spinning.
Flat spins are particularly hazardous because the level attitude and reduced airflow over the control surfaces make it difficult to regain control of the airplane.
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