Spiral is the stall of the plane. If there is yaw, the lift on the wing will be unbalanced and then spiral down around this axis. When the resistance increases, the decline rate will not increase after reaching a certain value, and the aircraft speed is also small, making it easier to get out.

The recovery method is to center the steering rod, push it forward, turn off the throttle, step on the rudder opposite to the landing direction, and resume the dive after the rotation stops.

What you said is more dangerous is spiral diving.

This is because the slope is too large when descending and turning. At this time, the wing did not stall, and the rate and speed of decline were very large, and it would get bigger and bigger, which was very dangerous.