Pilot/Controller Glossary 

12/2/21 

SFA

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(See SINGLE FREQUENCY APPROACH.) 

SFO

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(See SIMULATED FLAMEOUT.) 

SHF

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(See SUPER HIGH FREQUENCY.) 

SHORT RANGE CLEARANCE

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 A clearance 

issued to a departing IFR flight which authorizes IFR 
flight to a specific fix short of the destination while 
air traffic control facilities are coordinating and 
obtaining the complete clearance. 

SHORT TAKEOFF AND LANDING AIRCRAFT 
(STOL)

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 An aircraft which, at some weight within its 

approved operating weight, is capable of operating 
from a runway in compliance with the applicable 
STOL characteristics, airworthiness, operations, 
noise, and pollution standards. 

(See VERTICAL TAKEOFF AND LANDING 

AIRCRAFT.) 

SIAP

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(See STANDARD INSTRUMENT APPROACH 

PROCEDURE.) 

SID

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(See STANDARD INSTRUMENT DEPARTURE.) 

SIDESTEP MANEUVER

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 A visual maneuver 

accomplished by a pilot at the completion of an 
instrument approach to permit a straight­in landing 
on a parallel runway not more than 1,200 feet to either 
side of the runway to which the instrument approach 
was conducted. 

(Refer to AIM.) 

SIGMET

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  A weather advisory issued concerning 

weather significant to the safety of all aircraft. 
SIGMET advisories cover severe and extreme 
turbulence, severe icing, and widespread dust or 
sandstorms that reduce visibility to less than 3 miles. 

(See AIRMET.) 
(See CONVECTIVE SIGMET.) 
(See CWA.) 
(See ICAO term SIGMET INFORMATION.) 
(See SAW.) 
(Refer to AIM.) 

SIGMET INFORMATION [ICAO]

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 Information 

issued by a meteorological watch office concerning 
the occurrence or expected occurrence of specified 

en­route weather phenomena which may affect the 
safety of aircraft operations. 

SIGNIFICANT METEOROLOGICAL INFOR-
MATION

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(See SIGMET.) 

SIGNIFICANT POINT

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 A point, whether a named 

intersection, a NAVAID, a fix derived from a 
NAVAID(s), or geographical coordinate expressed in 
degrees of latitude and longitude, which is 
established for the purpose of providing separation, 
as a reporting point, or to delineate a route of flight. 

SIMPLIFIED DIRECTIONAL FACILITY (SDF)

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A NAVAID used for nonprecision instrument 
approaches. The final approach course is similar to 
that of an ILS localizer except that the SDF course 
may be offset from the runway, generally not more 
than 3 degrees, and the course may be wider than the 
localizer, resulting in a lower degree of accuracy. 

(Refer to AIM.) 

SIMULATED FLAMEOUT

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 A practice approach 

by a jet aircraft (normally military) at idle thrust to a 
runway. The approach may start at a runway (high 
key) and may continue on a relatively high and wide 
downwind leg with a continuous turn to final. It 
terminates in landing or low approach. The purpose 
of this approach is to simulate a flameout. 

(See FLAMEOUT.) 

SIMULTANEOUS CLOSE PARALLEL AP­
PROACHES

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 A simultaneous, independent 

approach operation permitting ILS/RNAV/GLS 
approaches to airports having parallel runways 
separated by at least 3,000 feet and less than 
4,300

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feet between centerlines. Aircraft are permit­

ted to pass each other during these simultaneous 
operations.  Integral parts of a total system are radar, 
NTZ monitoring with enhanced FMA color displays 
that include aural and visual alerts and predictive 
aircraft position software, communications override, 
ATC procedures, an Attention All Users Page 
(AAUP), PRM in the approach name, and 
appropriate ground based and airborne equipment. 
High update rate surveillance sensor required for 
certain runway or approach course separations. 

SIMULTANEOUS (CONVERGING) DEPEND­
ENT APPROACHES­ An approach operation 
permitting ILS/RNAV/GLS approaches to runways 
or missed approach courses that intersect where 
required minimum spacing between the aircraft on 
each final approach course is required. 

PCG S

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