Stall turn

Aresti Catalog's notation of Stall Turn

A Stall Turn, also known as a Hammerhead Turn, or Fieseler (named after Gerhard Fieseler), is an aerobatics turn-round maneuver. The pilot pulls the aircraft up into a vertical climb of a few hundred feet then lets the speed decay. Just before the airspeed reaches zero he applies full rudder to yaw the aircraft through a cartwheel of 180° until the nose is straight down. He corrects and dives vertically to the same altitude as the maneuver started, then pulls out exiting in the opposite direction.

This maneuver has also been called the SAR reversal (search and rescue reversal). Helicopters fly this maneuver when hunting survivors or submarines for it brings the aircraft directly back along the same course to verify the target. The SAR reversal doesn't necessarily need to be accomplished in VMC (visual meteorological conditions) if the pilot is proficient at maintaining aircraft attitude and altitude control throughout the entire maneuver by keeping the lateral acceleration ball centered for any uncoordinated lateral acceleration will induce spatial disorientation which at low altitudes leaves insufficient time to correct speed, attitude, altitude divergences