Spatial disorientation.  The state of confusion due to  misleading information being sent to the brain from various  sensory organs, resulting in a lack of awareness of the aircraft  position in relation to a specific reference point.  Stability.  The inherent quality of an airplane to correct for  conditions that may disturb its equilibrium, and to return  or to continue on the original flight path. It is primarily an  airplane design characteristic.  Special flight permit.  A flight permit issued to an aircraft  that does not meet airworthiness requirements but is capable  of safe flight. A special flight permit can be issued to move  an aircraft for the purposes of maintenance or repair, buyer  delivery, manufacturer flight tests, evacuation from danger,  or customer demonstration. Also referred to as a ferry permit.  Special use airspace.  Airspace in which flight activities are  subject to restrictions that can create limitations on the mixed  use of airspace. Consists of prohibited, restricted, warning,  military operations, and alert areas.  Special fuel consumption.  The amount of fuel in pounds  per hour consumed or required by an engine per brake  horsepower or per pound of thrust.  Speed.  The distance traveled in a given time.  Spin.  An aggravated stall that results in an airplane  descending in a helical, or corkscrew path.  Spiral instability.  A condition that exists when the static  directional stability of the airplane is very strong as compared  to the effect of its dihedral in maintaining lateral equilibrium.  Spiraling slipstream.  The slipstream of a propeller-driven  airplane rotates around the airplane. This slipstream strikes  the left side of the vertical fin, causing the aircraft to yaw  slightly. Rudder offset is sometimes used by aircraft designers  to counteract this tendency.  Spoilers.  High-drag devices that can be raised into the air  flowing over an airfoil, reducing lift and increasing drag.  Spoilers are used for roll control on some aircraft. Deploying  spoilers on both wings at the same time allows the aircraft  to descend without gaining speed. Spoilers are also used to  shorten the ground roll after landing.  SRM.  See single-pilot resource management.  SSR.  See secondary surveillance radar.  SSV.  See standard service volume.  Stabilator.  A single-piece horizontal tail surface on an  airplane that pivots around a central hinge point. A stabilator  serves the purposes of both the horizontal stabilizer and the  elevators.  Stagnant hypoxia.  A type of hypoxia that results when the  oxygen-rich blood in the lungs is not moving to the tissues  that need it.  Stall.  A rapid decrease in lift caused by the separation of  airflow from the wing’s surface, brought on by exceeding  the critical angle of attack. A stall can occur at any pitch  attitude or airspeed.  Standard atmosphere.  At sea level, the standard atmosphere  consists of a barometric pressure of 29.92 inches of mercury  ("Hg) or 1013.2 millibars, and a temperature of 15 °C (59  °F). Pressure and temperature normally decrease as altitude  increases. The standard lapse rate in the lower atmosphere for  each 1,000 feet of altitude is approximately 1 "Hg and 2 °C  (3.5 °F). For example, the standard pressure and temperature  at 3,000 feet mean sea level (MSL) are 26.92 "Hg (29.92  "Hg – 3 "Hg) and 9 °C (15 °C – 6 °C).  Standard empty weight (GAMA).  This weight consists of  the airframe, engines, and all items of operating equipment  that have fixed locations and are permanently installed in the  airplane including fixed ballast, hydraulic fluid, unusable  fuel, and full engine oil.  Standard holding pattern.  A holding pattern in which all  turns are made to the right.  Standard instrument departure procedures (SIDS).  Published procedures to expedite clearance delivery and to  facilitate transition between takeoff and en route operations.  Standard rate turn.  A turn in which an aircraft changes its  direction at a rate of 3° per second (360° in 2 minutes) for  low- or medium-speed aircraft. For high-speed aircraft, the  standard rate turn is 1½° per second (360° in 4 minutes).  Standard service volume (SSV).  Defines the limits of the  volume of airspace which the VOR serves.  Standard terminal arrival route (STAR).  A preplanned  IFR ATC arrival procedure published for pilot use in graphic  and/or textual form.  Standard weights.  Weights established for numerous items  involved in weight and balance computations. These weights  should not be used if actual weights are available.  G-28 