Pilot/Controller Glossary

e. Prohibited Area- Airspace designated under 14 CFR Part 73 within which no person may operate an
aircraft without the permission of the using agency.
(Refer to AIM.)
(Refer to En Route Charts.)

f. Restricted Area- Permanent and temporary restricted areas are airspace designated under 14 CFR Part 73,
within which the flight of aircraft, while not wholly prohibited, is subject to restriction. Most restricted areas
are designated joint use and IFR/VFR operations in the area may be authorized by the controlling ATC facility
when it is not being utilized by the using agency. Permanent restricted areas are depicted on Sectional
Aeronautical, VFR Terminal Area, and applicable En Route charts. Where joint use is authorized, the name of
the ATC controlling facility is also shown.
Note: Temporary restricted areas are not charted.
(Refer to 14 CFR Part 73.)
(Refer to AIM.)

g. Warning Area- A warning area is airspace of defined dimensions extending from 3 nautical miles outward
from the coast of the United States, that contains activity that may be hazardous to nonparticipating aircraft. The
purpose of such warning area is to warn nonparticipating pilots of the potential danger. A warning area may be
located over domestic or international waters or both.
SPECIAL VFR CONDITIONS- Meteorological conditions that are less than those required for basic VFR flight
in Class B, C, D, or E surface areas and in which some aircraft are permitted flight under visual flight rules.
(See SPECIAL VFR OPERATIONS.)
(Refer to 14 CFR Part 91.)

SPECIAL VFR FLIGHT [ICAO]- A VFR flight cleared by air traffic control to operate within Class B, C, D,
and E surface areas in meteorological conditions below VMC.
SPECIAL VFR OPERATIONS- Aircraft operating in accordance with clearances within Class B, C, D, and E
surface areas in weather conditions less than the basic VFR weather minima. Such operations must be requested
by the pilot and approved by ATC.
(See SPECIAL VFR CONDITIONS.)
(See ICAO term SPECIAL VFR FLIGHT.)

SPECIALIST-PROVIDED SERVICES"
Services delivered directly by a flight service specialist via ground/ground communication, air/ground
communication, in-person, or technology (for example, speech-to-text, email, or short message service).
SPEED-
(See AIRSPEED.)
(See GROUND SPEED.)

SPEED ADJUSTMENT- An ATC procedure used to request pilots to adjust aircraft speed to a specific value
for the purpose of providing desired spacing. Pilots are expected to maintain a speed of plus or minus 10 knots
or 0.02 Mach number of the specified speed. Examples of speed adjustments are:
a. "Increase/reduce speed to Mach point (number)."
b. "Increase/reduce speed to (speed in knots)" or "Increase/reduce speed (number of knots) knots."
SPEED BRAKES- Moveable aerodynamic devices on aircraft that reduce airspeed during descent and landing.
SPEED SEGMENTS- Portions of the arrival route between the transition point and the vertex along the
optimum flight path for which speeds and altitudes are specified. There is one set of arrival speed segments
adapted from each transition point to each vertex. Each set may contain up to six segments.
SPOOFING- Denotes emissions of GNSS-like signals that may be acquired and tracked in combination with
or instead of the intended signals by civil receivers. The onset of spoofing effects can be instantaneous or delayed,
and effects can persist after the spoofing has ended. Spoofing can result in false and potentially confusing, or
hazardously misleading, position, navigation, and/or date/time information in addition to loss of GNSS use.