COOPERATIVE OR GROUP LEARNING
An instructional strategy which organizes students into small groups so that they can work together to maximize their own and each other’s learning.

COORDINATED FLIGHT
Flight with a minimum disturbance of the forces maintaining equilibrium, established via effective control use.

COORDINATED TURN
Turn made by an aircraft where the horizontal component of lift is equal to the centrifugal force of the turn.

COORDINATES
The intersection of lines of reference, usually expressed in degrees/minutes/ seconds of latitude and longitude, used to determine position or location.
COORDINATION FIX
The fix in relation to which facilities will handoff, transfer control of an aircraft, or coordinate flight progress data. For terminal facilities, it may also serve as a clearance for arriving aircraft.

COP
See changeover point.

COPTER
(See HELICOPTER.)

CORIOLIS EFFECT
The tendency of a rotor blade to increase or decrease its velocity in its plane of rotation when the center of mass moves closer or further from the axis of rotation.

CORIOLIS ILLUSION
The illusion of rotation or movement in an entirely different axis, caused by an abrupt head movement, while in a prolonged constant-rate turn that has ceased to stimulate the brain’s motion sensing system.

CORRECTION
An error has been made in the transmission and the correct version follows.

CORRELATION
A basic level of learning where the student can associate what has been learned, understood, and applied with previous or subsequent learning.

COUPLED AILERONS AND RUDDER
Rudder and ailerons are connected with interconnected springs in order to counteract adverse yaw. Can be overridden if it becomes necessary to slip the aircraft.

COUPLED APPROACH
An instrument approach performed by the aircraft autopilot, and/or visually depicted on the flight director, which is receiving position information and/or steering commands from onboard navigational equipment. In general, coupled non-precision approaches must be flown manually (autopilot disengaged) at altitudes lower than 50 feet AGL below the minimum descent altitude, and coupled precision approaches must be flown manually (autopilot disengaged) below 50 feet AGL unless authorized to conduct auto land operations. Coupled instrument approaches are commonly flown to the allowable IFR weather minima established by the operator or PIC, or flown VFR for training and safety.

COURSE
a. The intended direction of flight in the horizontal plane measured in degrees from north. b. The ILS localizer signal pattern usually specified as the front course or the back course. c. The intended track along a straight, curved, or segmented MLS path. (See BEARING.) (See INSTRUMENT LANDING SYSTEM.) (See MICROWAVE LANDING SYSTEM.) (See RADIAL.)

COURSE OF TRAINING
A complete series of studies leading to attainment of a specific goal, such as a certificate of completion, graduation, or an academic degree.

COWL FLAPS
Shutter-like devices arranged around certain air-cooled engine cowlings, which may be opened or closed to regulate the flow of air around the engine.

CPDLC
(See CONTROLLER PILOT DATA LINK COMMUNICATIONS.)

CPL [ICAO]
(See ICAO term CURRENT FLIGHT PLAN.)

CRAB ANGLE
The angle formed between the direction an aircraft is pointed and the direction it is tracking over the ground, resulting from a crosswind component. Also called the wind correction angle.

CREST
The top of a wave.

CREW CHIEF
A crew member who is assigned the responsibility of organizing and directing other crewmembers.

CREW RESOURCE MANAGEMENT (CRM)
The application of team management concepts in the flight deck environment. It was initially known as cockpit resource management, but as CRM programs evolved to include cabin crews, maintenance personnel and others, the phrase “crew resource management” has been adopted. This includes single pilots, as in most general aviation aircraft. Pilots of small aircraft, as well as crews of larger aircraft, must make effective use of all available resources; human resources, hardware, and information. A current definition includes all groups routinely working with the cockpit crew who are involved in decisions required to operate a flight safely. These groups include, but are not limited to: pilots, dispatchers, cabin crewmembers, maintenance personnel, and air traffic controllers. CRM is one way of addressing the challenge of optimizing the human/machine interface and accompanying interpersonal activities.

CREWMEMBER
A person assigned to perform duty in an aircraft during flight time.

CRITERIA
The third part of a performance-based objective, descriptions of standards that will be used to measure the accomplishment of the objective.

CRITERION-REFERENCED TESTING
System of testing where students are graded against a carefully written, measurable standard or criterion rather than against each other.

CRITICAL ALTITUDE
The maximum altitude under standard atmospheric conditions at which a turbocharged engine can produce its rated horsepower.

CRITICAL ANGLE OF ATTACK
The angle of attack at which a wing stalls regardless of airspeed, flight attitude, or weight.

CRITICAL AREAS
Areas where disturbances to the ILS localizer and glide slope courses may occur when surface vehicles or aircraft operate near the localizer or glide slope antennas.

CRITICAL ENGINE
The engine which, upon failure, would most adversely affect the performance or handling qualities of an aircraft. CROSS (FIX)

CRM
See crew resource management.

CROSSBAR
The structural component of the WSC wing that holds the leading edges in place.

CROSS-CHECK
The first fundamental skill of instrument flight, also known as “scan,” the continuous and logical observation of instruments for attitude and performance information.

CROSS-COUNTRY
In soaring, any flight out of gliding range of the takeoff airfield. Note that this is different from the definitions in the 14 CFR for meeting the experience requirements for various pilot certificates and/or ratings.

CROSSWIND
Wind blowing across rather than parallel to the direction of flight. In a traffic pattern, the crosswind leg is a flight path at right angles to the landing runway off its upwind end.

CROSSWIND COMPONENT
The wind component measured in knots at 90 degrees to the longitudinal axis of the runway.

CROSSWIND CORRECTION
Correction applied in order to maintain a straight ground track during flight when a crosswind is present.

CROSSWIND LANDING
Landing made with a wind that is blowing across rather than parallel to the landing direction.

CROSSWIND LEG
A flight path at right angles to the landing runway off its upwind end.


CROSSWIND TAKEOFFS
Takeoffs made during crosswind conditions.

CROWN LINE
A line attached to the top of most balloons to assist in the inflation and deflation of the envelope. Sometimes referred to as apex line or top handling line.

CRUISE
Used in an ATC clearance to authorize a pilot to conduct flight at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. The pilot may level off at any intermediate altitude within this block of airspace. Climb/descent within the block is to be made at the discretion of the pilot. However, once the pilot starts descent and verbally reports leaving an altitude in the block, he/she may not return to that altitude without additional ATC clearance. Further, it is approval for the pilot to proceed to and make an approach at destination airport and can be used in conjunction with: a. An airport clearance limit at locations with a standard/special instrument approach procedure. The CFRs require that if an instrument letdown to an airport is necessary, the pilot shall make the letdown in accordance with a standard/special instrument approach procedure for that airport, or b. An airport clearance limit at locations that are within/below/outside controlled airspace and without a standard/special instrument approach procedure. Such a clearance is NOT AUTHORIZATION for the pilot to descend under IFR conditions below the applicable minimum IFR altitude.

CRUISE CLEARANCE
An ATC clearance issued to allow a pilot to conduct flight at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. Also authorizes a pilot to proceed to and make an approach at the destination airport.

CRUISE CLIMB
A climb technique employed by aircraft, usually at a constant power setting, resulting in an increase of altitude as the aircraft weight decreases.

CRUISING ALTITUDE
An altitude or flight level maintained during en route level flight. This is a constant altitude and should not be confused with a cruise clearance. (See ALTITUDE.) (See ICAO term CRUISING LEVEL.)

CRUISING LEVEL
(See CRUISING ALTITUDE.)

CRUISING LEVEL [ICAO]
A level maintained during a significant portion of a flight.

CT MESSAGE
An EDCT time generated by the ATCSCC to regulate traffic at arrival airports. Normally, a CT message is automatically transferred from the traffic management system computer to the NAS en route computer and appears as an EDCT. In the event of a communication failure between the traffic management system computer and the NAS, the CT message can be manually entered by the TMC at the en route facility.

CTA
(See CONTROLLED TIME OF ARRIVAL.) (See ICAO term CONTROL AREA.)

CTAF
See Common Traffic Advisory Frequency.

CTAS
(See CENTER TRACON AUTOMATION SYSTEM.)

CTRD
(See CERTIFIED TOWER RADAR DISPLAY.)

CUMULONIMBUS (CB)
Also called thunderclouds, these are deep convective clouds with a cirrus anvil and may contain any of the characteristics of a thunderstorm: thunder, lightning, heavy rain, hail, strong winds, turbulence, and even tornadoes.

CUMULUS CONGESTUS
A cumulus cloud of significant vertical extent and usually displaying sharp edges. In warm climates, these sometimes produce precipitation. Also called towering cumulus, these clouds indicate that thunderstorm activity may soon occur.

CURRENCY
Common usage for recent flight experience. In order to carry passengers, a pilot must have performed three takeoffs and three landings within the preceding 90 days. In order to carry passengers at night, a pilot must have performed three takeoffs and three landings to a full stop at night (the period beginning 1 hour after sunset and ending 1 hour before sunrise).

CURRENT
The horizontal movement of a body of water.

CURRENT FLIGHT PLAN [ICAO]
The flight plan, including changes, if any, brought about by subsequent clearances.

CURRENT INDUCTION
An electrical current being induced into, or generated in, any conductor that is crossed by lines of flux from any magnet.

CURRENT PLAN
The ATC clearance the aircraft has received and is expected to fly.

CURRICULUM
A set of courses in an area of specialization offered by an educational institution. A curriculum for a pilot school usually includes courses for the various pilot certificates and ratings.

CUT-AWAY
Model of an object that is built in sections so it can be taken apart to reveal the inner structure.

CVFP APPROACH
(See CHARTED VISUAL FLIGHT PROCEDURE APPROACH.)

CWA
(See CENTER WEATHER ADVISORY and WEATHER ADVISORY.)

CYCLIC FEATHERING
The mechanical change of the angle of incidence, or pitch, of individual rotor blades independently of other blades in the system.

CYCLIC PITCH CONTROL
The control for changing the pitch of each rotor blade individually as it rotates through one cycle to govern the tilt of the rotor disc and, consequently, the direction and velocity of horizontal movement.
P-ACP
(See PREARRANGED COORDINATION PROCEDURES.)

PAN-PAN
The international radio-telephony urgency signal. When repeated three times, indicates uncertainty or alert followed by the nature of the urgency. (See MAYDAY.) (Refer to AIM.)

PAR
(See PRECISION APPROACH RADAR.)

PAR [ICAO]
(See ICAO Term PRECISION APPROACH RADAR.)

PARALLEL ILS APPROACHES
Approaches to parallel runways by IFR aircraft which, when established inbound toward the airport on the adjacent final approach courses, are radar-separated by at least 2 miles. (See FINAL APPROACH COURSE.) (See SIMULTANEOUS ILS APPROACHES.)

PARALLEL OFFSET ROUTE
A parallel track to the left or right of the designated or established airway/route. Normally associated with Area Navigation (RNAV) operations. (See AREA NAVIGATION.)

PARALLEL RUNWAYS
Two or more runways at the same airport whose centerlines are parallel. In addition to runway number, parallel runways are designated as L (left) and R (right) or, if three parallel runways exist, L (left), C (center), and R (right).

PBCT
(See PROPOSED BOUNDARY CROSSING TIME.) PBN (See ICAO Term

PBCT. PROPOSED DEPARTURE TIME
The time that the aircraft expects to become airborne.

PERFORMANCE
ASED NAVIGATION.)

PERMANENT ECHO
Radar signals reflected from fixed objects on the earth’s surface; e.g., buildings, towers, terrain. Permanent echoes are distinguished from “ground clutter” by being definable locations rather than large areas. Under certain conditions they may be used to check radar alignment.

PHOTO RECONNAISSANCE
Military activity that requires locating individual photo targets and navigating to the targets at a preplanned angle and altitude. The activity normally requires a lateral route width of 16 NM and altitude range of 1,500 feet to 10,000 feet

PILOT IN COMMAND
The pilot responsible for the operation and safety of an aircraft during flight time. (Refer to 14 CFR Part 91.)

PILOT WEATHER REPORT
A report of meteorological phenomena encountered by aircraft in flight. (Refer to AIM.)

PILOT’S DISCRETION
When used in conjunction with altitude assignments, means that ATC has offered the pilot the option of starting climb or descent whenever he/she wishes and conducting the climb or descent at any rate he/she wishes. He/she may temporarily level off at any intermediate altitude. However, once he/she has vacated an altitude, he/she may not return to that altitude.

PLANS DISPLAY
A display available in URET that provides detailed flight plan and predicted conflict information in textual format for requested Current Plans and all Trial Plans. (See USER REQUEST EVALUATION TOOL.)

POFZ
(See PRECISION OBSTACLE FREE ZONE.)

POINT OUT
(See RADAR POINT OUT.)

POLAR TRACK STRUCTURE
A system of organized routes between Iceland and Alaska which overlie Canadian MNPS Airspace.

POSITION REPORT
A report over a known location as transmitted by an aircraft to ATC. (Refer to AIM.)

POSITION SYMBOL
A computer-generated indication shown on a radar display to indicate the mode of tracking.

POSITIVE CONTROL
The separation of all air traffic within designated airspace by air traffic control.

PRACTICE INSTRUMENT APPROACH
An instrument approach procedure conducted by a VFR or an IFR aircraft for the purpose of pilot training or proficiency demonstrations.
PRE
EPARTURE CLEARANCE.)

PREARRANGED COORDINATION
A standardized procedure which permits an air traffic controller to enter the airspace assigned to another air traffic controller without verbal coordination. The procedures are defined in a facility directive which ensures standard separation between aircraft.

PREARRANGED COORDINATION PROCEDURES
A facility’s standardized procedure that describes the process by which one controller shall allow an aircraft to penetrate or transit another controller’s airspace in a manner that assures standard separation without individual coordination for each aircraft.

PRECIPITATION
Any or all forms of water particles (rain, sleet, hail, or snow) that fall from the atmosphere and reach the surface.

PRECIPITATION RADAR WEATHER DESCRIPTIONS
Existing radar systems cannot detect turbulence. However, there is a direct correlation between the degree of turbulence and other weather features associated with thunderstorms and the weather radar precipitation intensity. Controllers will issue (where capable) precipitation intensity as observed by radar when using weather and radar processor (WARP) or NAS ground based digital radars with weather capabilities. When precipitation intensity information is not available, the intensity will be described as UNKNOWN. When intensity levels can be determined, they shall be described as: a. LIGHT (< 30 dBZ) b. MODERATE (30 to 40 dBZ) c. HEAVY (> 40 to 50 dBZ) d. EXTREME (> 50 dBZ) (Refer to

PRECISION APPROACH
(See PRECISION APPROACH PROCEDURE.)

PRECISION APPROACH PROCEDURE
A standard instrument approach procedure in which an electronic glideslope/or other type of glidepath is provided ; e.g., ILS, PAR, and GLS. (See INSTRUMENT LANDING SYSTEM.) (See PRECISION APPROACH RADAR.)

PRECISION APPROACH RADAR [ICAO]
Primary radar equipment used to determine the position of an aircraft during final approach, in terms of lateral and vertical deviations relative to a nominal approach path, and in range relative to touchdown. Note: Precision approach radars are designed to enable pilots of aircraft to be given guidance by radio communication during the final stages of the approach to land.

PRECISION OBSTACLE FREE ZONE (POFZ)
An 800 foot wide by 200 foot long area centered on the runway centerline adjacent to the threshold designed to protect aircraft flying precision approaches from ground vehicles and other aircraft when ceiling is less than 250 feet or visibility is less than 3/4 statute mile (or runway visual range below 4,000 feet.) PRECISION RUNWAY MONITOR (PRM)

PREFERENTIAL ROUTES
Preferential routes (PDRs, PARs, and PDARs) are adapted in ARTCC computers to accomplish inter/intrafacility controller coordination and to assure that flight data is posted at the proper control positions. Locations having a need for these specific inbound and outbound routes normally publish such routes in local facility bulletins, and their use by pilots minimizes flight plan route amendments. When the workload or traffic situation permits, controllers normally provide radar vectors or assign requested routes to minimize circuitous routing. Preferential routes are usually confined to one ARTCC’s area and are referred to by the following names or acronyms: a. Preferential Departure Route (PDR). A specific departure route from an airport or terminal area to an en route point where there is no further need for flow control. It may be included in an Instrument Departure Procedure (DP) or a Preferred IFR Route. b. Preferential Arrival Route (PAR). A specific arrival route from an appropriate en route point to an airport or terminal area. It may be included in a Standard Terminal Arrival (STAR) or a Preferred IFR Route. The abbreviation “PAR” is used primarily within the ARTCC and should not be confused with the abbreviation for Precision Approach Radar. c. Preferential Departure and Arrival Route (PDAR). A route between two terminals which are within or immediately adjacent to one ARTCC’s area. PDARs are not synonymous with Preferred IFR Routes but may be listed as such as they do accomplish essentially the same purpose. (See PREFERRED IFR ROUTES.)

PRE-FLIGHT PILOT BRIEFING
(See PILOT BRIEFING.)

PREVAILING VISIBILITY
(See VISIBILITY.)

PRIMARY RADAR TARGET
An analog or digital target, exclusive of a secondary radar target, presented on a radar display.

PRM
(See ILS PRM APPROACH and PRECISION RUNWAY MONITOR SYSTEM.)

PROCEDURE TURN
The maneuver prescribed when it is necessary to reverse direction to establish an aircraft on the intermediate approach segment or final approach course. The outbound course, direction of turn, distance within which the turn must be completed, and minimum altitude are specified in the procedure. However, unless otherwise restricted, the point at which the turn may be commenced and the type and rate of turn are left to the discretion of the pilot. (See ICAO term PROCEDURE TURN.)

PROCEDURE TURN [ICAO]
A maneuver in which a turn is made away from a designated track followed by a turn in the opposite direction to permit the aircraft to intercept and proceed along the reciprocal of the designated track. Note 1: Procedure turns are designated “left” or “right” according to the direction of the initial turn. Note 2: Procedure turns may be designated as being made either in level flight or while descending, according to the circumstances of each individual approach procedure.

PROCEDURE TURN INBOUND
That point of a procedure turn maneuver where course reversal has been completed and an aircraft is established inbound on the intermediate approach segment or final approach course. A report of “procedure turn inbound” is normally used by ATC as a position report for separation purposes. (See FINAL APPROACH COURSE.) (See PROCEDURE TURN.) (See SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE.)

PROFILE DESCENT
An uninterrupted descent (except where level flight is required for speed adjustment; e.g., 250 knots at 10,000 feet MSL) from cruising altitude/level to interception of a glideslope or to a minimum altitude specified for the initial or intermediate approach segment of a nonprecision instrument approach. The profile descent normally terminates at the approach gate or where the glideslope or other appropriate minimum altitude is intercepted.

PROGRESS REPORT
(See POSITION REPORT.)

PROGRESSIVE TAXI
Precise taxi instructions given to a pilot unfamiliar with the airport or issued in stages as the aircraft proceeds along the taxi route.

PROHIBITED AREA
(See SPECIAL USE AIRSPACE.) (See ICAO term PROHIBITED AREA.)

PROPOSED BOUNDARY CROSSING TIME
Each center has a PBCT parameter for each internal airport. Proposed internal flight plans are transmitted to the adjacent center if the flight time along the proposed route from the departure airport to the center boundary is less than or equal to the value of PBCT or if airport adaptation specifies transmission regardless of
PROTECTED AIRSPACE
The airspace on either side of an oceanic route/track that is equal to one-half the lateral separation minimum except where reduction of protected airspace has been authorized. PROTECTED SEGMENT- The protected segment is a segment on the amended TFM route that is to be inhibited from automatic adapted route alteration by

PTS
(See POLAR TRACK STRUCTURE.)

PUBLISHED INSTRUMENT APPROACH PROCEDURE VISUAL SEGMENT
A segment on an IAP chart annotated as “Fly Visual to Airport” or “Fly Visual.” A dashed arrow will indicate the visual flight path on the profile and plan view with an associated note on the approximate heading and distance. The visual segment should be flown as a dead reckoning course while maintaining visual conditions.

PUBLISHED ROUTE
A route for which an IFR altitude has been established and published; e.g., Federal Airways, Jet Routes, Area Navigation Routes, Specified Direct Routes.

PVD/MDM. MFT
(See METER FIX TIME/SLOT TIME.)

PWS
(See PREDICTIVE WIND SHEARSYSTEM.)