A condition in which airplane loses the airflow around all of it's aerodynamic surfaces. This phenomenon occurs usually with tailless delta-winged or T-tailed airplanes in which the stalling wing blocks the elevator. In deep stall, the airplane will fall in any attitude, usually oscillating along it's longitudal axis. To exit deep stall, the best method is to consent with the oscillations, to make them larger. This way, the airplane will end up in nose-down attitude and aerodynamic surfaces regain their effect. A very dangerous situation.