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
(See SECTOR LIST DROP INTERVAL.)
(See METER FIX TIME/SLOT TIME.)
SLOW TAXI- To taxi a float plane at low power or
(See SYSTEM STRATEGIC NAVIGATION.)
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 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
SPECIAL INSTRUMENT APPROACH PROCE-
(See INSTRUMENT APPROACH PROCEDURE.)
SPECIAL USE AIRSPACE- Airspace of defined
dimensions identified by an area on the surface of the
earth wherein activities must be confined because of
their nature and/or wherein limitations may be
imposed upon aircraft operations that are not a part of
those activities. Types of special use airspace are:
a. Alert Area- Airspace which may contain a high
volume of pilot training activities or an unusual type
of aerial activity, neither of which is hazardous to
aircraft. Alert Areas are depicted on aeronautical
charts for the information of nonparticipating pilots.
All activities within an Alert Area are conducted in
accordance with Federal Aviation Regulations, and
pilots of participating aircraft as well as pilots
transiting the area are equally responsible for
b. Controlled Firing Area- Airspace wherein
activities are conducted under conditions so
controlled as to eliminate hazards to nonparticipating
aircraft and to ensure the safety of persons and
property on the ground.
c. Military Operations Area (MOA)- A MOA is
airspace established outside of Class A airspace area
to separate or segregate certain nonhazardous
military activities from IFR traffic and to identify for
VFR traffic where these activities are conducted.
(Refer to AIM.)
d. Prohibited Area- Airspace designated under
14 CFR Part 73 within which no person may operate