to the runway threshold, visual separation by the aircraft conducting the offset approach is utilized. 

(Refer to AIM) 

SIMULTANEOUS (PARALLEL) DEPENDENT APPROACHES- An approach operation permitting ILS/RNAV/GLS approaches to adjacent parallel runways where prescribed diagonal spacing must be maintained. Aircraft are not permitted to pass each other during simultaneous dependent operations. Integral parts of a total system ATC procedures, and appropriate airborne and ground based equipment. 

SINGLE DIRECTION ROUTES- Preferred IFR Routes which are sometimes depicted on high altitude en route charts and which are normally flown in one direction only. 

(See PREFERRED IFR ROUTES.) (Refer to CHART SUPPLEMENT U.S.) 

SINGLE FREQUENCY APPROACH- A service provided under a letter of agreement to military single-piloted turbojet aircraft which permits use of a single UHF frequency during approach for landing. Pilots will not normally be required to change frequency from the beginning of the approach to touchdown except that pilots conducting an en route descent are required to change frequency when control is transferred from the air route traffic control center to the terminal facility. The abbreviation “SFA” in the DOD FLIP IFR Supplement under “Communications” indicates this service is available at an aerodrome. 

SINGLE-PILOTED AIRCRAFT- A military turbojet aircraft possessing one set of flight controls, tandem cockpits, or two sets of flight controls but operated by one pilot is considered single-piloted by ATC when determining the appropriate air traffic service to be applied. 

(See SINGLE FREQUENCY APPROACH.) 

SKYSPOTTER- A pilot who has received specialized training in observing and reporting inflight weather phenomena. 

SLASH- A radar beacon reply displayed as an elongated target. 

SLDI- 

(See SECTOR LIST DROP INTERVAL.) 

SLOT TIME- 

(See METER FIX TIME/SLOT TIME.) 

SLOW TAXI- To taxi a float plane at low power or low RPM. 

SN- 

(See SYSTEM STRATEGIC NAVIGATION.) 

SPACE-BASED ADS-B (SBA)- A constellation of satellites that receives ADS-B Out broadcasts and relays that information to the appropriate surveil- lance facility. The currently deployed SBA system is only capable of receiving broadcasts from 1090ES- equipped aircraft, and not from those equipped with only a universal access transceiver (UAT). Also, aircraft with a top-of-fuselage-mounted transponder antenna (required for TCAS II installations) will be better received by SBA, especially at latitudes below 45 degrees. 

(See AUTOMATIC DEPENDENT SURVEILLANCE-BROADCAST.) (See AUTOMATIC DEPENDENT SURVEILLANCE-BROADCAST OUT.) 

SPEAK SLOWER- Used in verbal communications as a request to reduce speech rate. 

SPECIAL ACTIVITY AIRSPACE (SAA)- Any airspace with defined dimensions within the National Airspace System wherein limitations may be imposed upon aircraft operations. This airspace may be restricted areas, prohibited areas, military operations areas, air ATC assigned airspace, and any other designated airspace areas. The dimensions of this airspace are programmed into EDST and can be designated as either active or inactive by screen entry. Aircraft trajectories are constantly tested against the dimensions of active areas and alerts issued to the applicable sectors when violations are predicted. 

(See EN ROUTE DECISION SUPPORT TOOL .) 

SPECIAL AIR TRAFFIC RULES (SATR)- Rules that govern procedures for conducting flights in certain areas listed in 14 CFR Part 93. The term “SATR" is used in the United States to describe the rules for operations in specific areas designated in the Code of Federal Regulations. 

(Refer to 14 CFR Part 93.) 

SPECIAL EMERGENCY- A condition of air piracy or other hostile act by a person(s) aboard an aircraft which threatens the safety of the aircraft or its passengers. 

SPECIAL FLIGHT RULES AREA (SFRA)- An area in the NAS, described in 14 CFR Part 93, wherein the flight of aircraft is subject to special 

