Spiral dive

The spiral dive is the most rapid form of controlled fast descent; an aggressive spiral dive can achieve a sink rate of 25 m s. This maneuver halts forward progress and brings the flier almost straight down. The pilot pulls the brakes on one side and shifts his weight onto that side to induce a sharp turn. The flight path then begins to resembles a corkscrew. After a specific downward speed is reached, the wing points directly to the ground. When the pilot reaches his desired height, he ends this maneuver by slowly releasing the inner break, shifting his weight to the outer side and braking on this side. The release of the inner brake has to be handled carefully to end the spiral dive gently in a few turns. If done too fast, the wing translates the turning into a dangerous upward and pendular motion. Spiral dives put a strong G force on the wing and glider and must be done carefully and skilfully. The G forces involved can induce blackouts, and the rotation can produce disorientation. Some high end gliders have what is called a stable spiral problem.[24] After inducing a spiral and without further pilot input, some wings do not automatically return to normal flight and stay inside their spiral. Serious injury and fatal accidents did occur when pilots could not exit this maneuver and spiraled into the ground.