Pilot/Controller Glossary

SIMULTANEOUS ILS APPROACHES- An approach system permitting simultaneous ILS approaches to
airports having parallel runways separated by at least 4,300 feet between centerlines. Integral parts of a total
system are ILS, radar, communications, ATC procedures, and appropriate airborne equipment.
(See PARALLEL RUNWAYS.)
(Refer to AIM.)

SIMULTANEOUS OFFSET INSTRUMENT APPROACH (SOIA)- An instrument landing system comprised
of an ILS PRM, RNAV PRM or GLS PRM approach to one runway and an offset LDA PRM with glideslope
or an RNAV PRM or GLS PRM approach utilizing vertical guidance to another where parallel runway spaced
less than 3,000 feet and at least 750 feet apart. The approach courses converge by 2.5 to 3 degrees. Simultaneous
close parallel PRM approach procedures apply up to the point where the approach course separation becomes
3,000 feet, at the offset MAP. From the offset MAP 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.)

SLOW TAXI- To taxi a float plane at low power or low RPM.
SMALL UNMANNED AIRCRAFT SYSTEM (sUAS)" An unmanned aircraft weighing less than 55 pounds
on takeoff, including everything that is on board or otherwise attached to the aircraft.
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 surveillance 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.)