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. 

Segmented circle.  A visual indicator around a windsock or tetrahedron designed to show the traffic pattern for each runway. 

Shallow-banked turn. Turns in which the bank is less than approximately 20 degrees. 

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. 

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. 

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. 

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. 

Skin. The outside covering of an aircraft airframe. 

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. 

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. 

Solo flight. Flight that is conducted and logged when a pilot is the sole occupant of an aircraft. 

Spatial disorientation.  Specifically refers to the lack of orientation with regard to the position, attitude, or movement of the WSC in space. 

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. 

