symmetrically about the runway centerline, or the number of  stripes is related to the runway width. A threshold marking  helps identify the beginning of the runway that is available  for landing. In some instances, the landing threshold may  be displaced. Safety directive.  A manufacturer issued change to a S-LSA  that must be complied with. This is similar to an airworthiness  directive which is a regulatory notice sent out by the FAA to  the registered owner of an aircraft informing the owner of a  condition that prevents the aircraft from continuing to meet  its conditions for airworthiness. Airworthiness Directives  (AD notes) must be complied with within the required time  limit, and the fact of compliance, the date of compliance, and  the method of compliance must be recorded in the aircraft’s  maintenance records. SAR.  See search and rescue. Scan.  A procedure used by the pilot to visually identify all  resources of information in flight. Scanning.  Systematic means of searching for other aircraft.  Scanning is most effective when successive areas of the  sky are brought into focus using a series of short, regularly  spaced eye movements. Scenario-based training.  The instructor provides pilot,  aircraft, environment, and operational risk elements to train  the student to utilize ADM in making the best decision for  the given set of circumstances. SD.  See safety directave. Sea level.  A reference height used to determine standard  atmospheric conditions and altitude measurements. Search and rescue (SAR).  A lifesaving service provided  through the combined efforts of the federal agencies signatory  to the National SAR plan along with state agencies. Sectional charts.  Designed for visual navigation of slow  or medium speed aircraft. Topographic information on  these charts features the portrayal of relief, and a judicious  selection of visual check points for VFR flight. Aeronautical  information includes visual and radio aids to navigation,  airports, controlled airspace, restricted areas, obstructions  and related data. See and avoid.  When weather conditions permit, pilots  operating IFR or VFR are required to observe and maneuver  to avoid other aircraft. Right-of-way rules are contained in  14 CFR part 91. 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. Spatial disorientation.  Specifically refers to the lack of  orientation with regard to the position, attitude, or movement  of the WSC in space. Solo flight.  Flight that is conducted and logged when a pilot  is the sole occupant of an aircraft. S-LSA (Special Light-Sport Aircraft). An aircraft issued a  special airworthiness certificate in accordance with 14 CFR  section 21.290 in the light-sport category. These aircraft meet  the ASTM industry-developed consensus standards. Skin friction drag.  The type of parasite drag resulting from  a rough surface which deflects the streamlines of air on the  surface, causing resistance to smooth airflow. Skin.  The outside covering of an aircraft airframe. Skills and procedures.  The procedural, psychomotor, and  perceptual skills used to control a specific aircraft or its  systems. They are the airmanship abilities that are gained  through conventional training, are perfected, and become  almost automatic through experience. Situational awareness.  The accurate perception and  understanding of all the factors and conditions within the four  fundamental risk elements that affect safety before, during,  and after the flight. Single surface wing.  one piece of fabric for most of the  airfoil on a WSC with the cross bar exposed to the airflow.  Typically used for slower wings. Single Pilot Resource Management (SRM).  Area of human  factors study that addresses application of management skills  in the cockpit. Single pilots of small aircraft must make  effective use of all available resources; human resources,  hardware, and information. Shallow-banked turn.  Turns in which the bank is less than  approximately 20 degrees. Segmented circle.  A visual indicator around a windsock  or tetrahedron designed to show the traffic pattern for each  runway. G-15