Synthetic vision. A realistic display depiction of the aircraft in relation to terrain and flight path.
T
TAA. See terminal arrival area.
TACAN. See tactical air navigation.
Tactical air navigation (TACAN). An electronic navigation system used by military aircraft, providing both distance and direction information.
Takeoff decision speed (V1). Per 14 CFR section 23.51: “the calibrated airspeed on the ground at which, as a result of engine failure or other reasons, the pilot assumed to have made a decision to continue or discontinue the takeoff.”
Takeoff distance. The distance required to complete an all-engines operative takeoff to the 35-foot height. It must be at least 15 percent less than the distance required for a one-engine inoperative engine takeoff. This distance is not normally a limiting factor as it is usually less than the one-engine inoperative takeoff distance.
Takeoff safety speed (V2). Per 14 CFR part 1: “A referenced airspeed obtained after lift-off at which the required one-engine-inoperative climb performance can be achieved.”
TAWS. See terrain awareness and warning system.
Taxiway lights. Omnidirectional lights that outline the edges of the taxiway and are blue in color.
Taxiway turnoff lights. Lights that are flush with the runway which emit a steady green color.
TCAS. See traffic alert collision avoidance system.
TCH. See threshold crossing height.
TDZE. See touchdown zone elevation.
TEC. See Tower En Route Control.
Technique. The manner in which procedures are executed.
Telephone information briefing service (TIBS). An FSS service providing continuously updated automated telephone recordings of area and/or route weather, airspace procedures, and special aviation-oriented announcements.
Temporary flight restriction (TFR). Restriction to flight imposed in order to:
1. Protect persons and property in the air or on the surface from an existing or imminent flight associated hazard;
2. Provide a safe environment for the operation of disaster relief aircraft;
3. Prevent an unsafe congestion of sightseeing aircraft above an incident;
4. Protect the President, Vice President, or other public figures; and,
5. Provide a safe environment for space agency operations.
Pilots are expected to check appropriate NOTAMs during flight planning when conducting flight in an area where a temporary flight restriction is in effect.
Tension. Maintaining an excessively strong grip on the control column, usually resulting in an overcontrolled situation.
Terminal aerodrome forecast (TAF). A report established for the 5 statute mile radius around an airport. Utilizes the same descriptors and abbreviations as the METAR report.
Terminal arrival area (TAA). A procedure to provide a new transition method for arriving aircraft equipped with FMS and/or GPS navigational equipment. The TAA contains a “T” structure that normally provides a NoPT for aircraft using the approach.
Terminal instrument approach procedure (TERP). Prescribes standardized methods for use in designing instrument flight procedures.
TERP. See terminal instrument approach procedure.
Terminal radar service areas (TRSA). Areas where participating pilots can receive additional radar services. The purpose of the service is to provide separation between all IFR operations and participating VFR aircraft.
Terrain awareness and warning system (TAWS). A timed-based system that provides information concerning potential hazards with fixed objects by using GPS positioning and a database of terrain and obstructions to provide true predictability of the upcoming terrain and obstacles.
TFR. See temporary flight restriction.
Thermosphere. The last layer of the atmosphere that begins above the mesosphere and gradually fades away into space.
Threshold crossing height (TCH). The theoretical height above the runway threshold at which the aircraft’s glideslope antenna would be if the aircraft maintained the trajectory established by the mean ILS glideslope or MLS glidepath.
Thrust. The force which imparts a change in the velocity of a mass. This force is measured in pounds but has no element of time or rate. The term “thrust required” is generally associated with jet engines. A forward force which propels the airplane through the air.
Thrust (aerodynamic force). The forward aerodynamic force produced by a propeller, fan, or turbojet engine as it forces a mass of air to the rear, behind the aircraft.
Thrust line. An imaginary line passing through the center of the propeller hub, perpendicular to the plane of the propeller rotation.
Time and speed table. A table depicted on an instrument approach procedure chart that identifies the distance from the FAF to the MAP, and provides the time required to transit that distance based on various groundspeeds.
Timed turn. A turn in which the clock and the turn coordinator are used to change heading a definite number of degrees in a given time.
TIS. See traffic information service.
Title 14 of the Code of Federal Regulations (14 CFR). Includes the federal aviation regulations governing the operation of aircraft, airways, and airmen.
Torque. (1) A resistance to turning or twisting. (2) Forces that produce a twisting or rotating motion. (3) In an airplane, the tendency of the aircraft to turn (roll) in the opposite direction of rotation of the engine and propeller. (4) In helicopters with a single, main rotor system, the tendency of the helicopter to turn in the opposite direction of the main rotor rotation.
Torquemeter. An instrument used with some of the larger reciprocating engines and turboprop or turboshaft engines to measure the reaction between the propeller reduction gears and the engine case.
Total drag. The sum of the parasite drag and induced drag.
Touchdown zone elevation (TDZE). The highest elevation in the first 3,000 feet of the landing surface, TDZE is indicated on the instrument approach procedure chart when straight-in landing minimums are authorized.
Touchdown zone lights. Two rows of transverse light bars disposed symmetrically about the runway centerline in the runway touchdown zone.
Tower En Route Control (TEC). The control of IFR en route traffic within delegated airspace between two or more adjacent approach control facilities, designed to expedite traffic and reduce control and pilot communication requirements.
TPP. See United States Terminal Procedures Publication.
Track. The actual path made over the ground in flight.
Tracking. Flying a heading that will maintain the desired track to or from the station regardless of crosswind conditions.
Traffic Alert Collision Avoidance System (TCAS). An airborne system developed by the FAA that operates independently from the ground-based Air Traffic Control system. Designed to increase flight deck awareness of proximate aircraft and to serve as a “last line of defense” for the prevention of midair collisions.
Traffic information service (TIS). A ground-based service providing information to the flight deck via data link using the S-mode transponder and altitude encoder to improve the safety and efficiency of “see and avoid” flight through an automatic display that informs the pilot of nearby traffic.
Trailing edge. The portion of the airfoil where the airflow over the upper surface rejoins the lower surface airflow.
Transcribed Weather Broadcast (TWEB). An FSS service, available in Alaska only, providing continuously updated automated broadcast of meteorological and aeronautical data over selected L/MF and VOR NAVAIDs.
Transponder. The airborne portion of the ATC radar beacon system.
Transponder code. One of 4,096 four-digit discrete codes ATC assigns to distinguish between aircraft.
Trend. Immediate indication of the direction of aircraft movement, as shown on instruments.
Tricycle gear. Landing gear employing a third wheel located on the nose of the aircraft.
Trim. To
adjust the aerodynamic forces on the control surfaces so that the aircraft maintains the set attitude without any control input.
Trim tab. A small auxiliary hinged portion of a movable control surface that can be adjusted during flight to a position resulting in a balance of control forces.
Tropopause. The boundary layer between the troposphere and the stratosphere which acts as a lid to confine most of the water vapor, and the associated weather, to the troposphere.
Troposphere. The layer of the atmosphere extending from the surface to a height of 20,000 to 60,000 feet, depending on latitude.
True airspeed. Actual airspeed, determined by applying a correction for pressure altitude and temperature to the CAS.
True altitude. The vertical distance of the airplane above sea level—the actual altitude. It is often expressed as feet above mean sea level (MSL). Airport, terrain, and obstacle elevations on aeronautical charts are true altitudes.
Truss. A fuselage design made up of supporting structural members that resist deformation by applied loads. The truss-type fuselage is constructed of steel or aluminum tubing. Strength and rigidity is achieved by welding the tubing together into a series of triangular shapes, called trusses.
T-tail. An aircraft with the horizontal stabilizer mounted on the top of the vertical stabilizer, forming a T.
Turbine discharge pressure. The total pressure at the discharge of the low-pressure turbine in a dual-turbine axial-flow engine.
Turbine engine. An aircraft engine which consists of an air compressor, a combustion section, and a turbine. Thrust is produced by increasing the velocity of the air flowing through the engine.
Turbocharger. An air compressor driven by exhaust gases, which increases the pressure of the air going into the engine through the carburetor or fuel injection system.
Turbofan engine. A fanlike turbojet engine designed to create additional thrust by diverting a secondary airflow around the combustion chamber.
Turbojet engine. A turbine engine which produces its thrust entirely by accelerating the air through the engine.
Turboprop engine. A turbine engine which drives a propeller through a reduction gearing arrangement. Most of the energy in the exhaust gases is converted into torque, rather than using its acceleration to drive the aircraft.
Turboshaft engine. A gas turbine engine that delivers power through a shaft to operate something other than a propeller.
Turn-and-slip indicator. A flight instrument consisting of a rate gyro to indicate the rate of yaw and a curved glass inclinometer to indicate the relationship between gravity and centrifugal force. The turn-and-slip indicator indicates the relationship between angle of bank and rate of yaw. Also called a turn-and-bank indicator.
Turn coordinator. A rate gyro that senses both roll and yaw due to the gimbal being canted. Has largely replaced the turn-and-slip indicator in modern aircraft.
TWEB. See Transcribed Weather Broadcast.
U
UHF. See ultra-high frequency.
Ultra-high frequency (UHF). The range of electromagnetic frequencies between 300 MHz and 3,000 MHz.
Ulitimate load factor. In stress analysis, the load that causes physical breakdown in an aircraft or aircraft component during a strength test, or the load that according to computations, should cause such a breakdown.
Uncaging. Unlocking the gimbals of a gyroscopic instrument, making it susceptible to damage by abrupt flight maneuvers or rough handling.
Uncontrolled airspace. Class G airspace that has not been designated as Class A, B, C, D, or E. It is airspace in which air traffic control has no authority or responsibility to control air traffic; however, pilots should remember there are VFR minimums which apply to this airspace.
Underpower. Using less power than required for the purpose of achieving a faster rate of airspeed change.
United States Terminal Procedures Publication (TPP). Booklets published in regional format by FAA Aeronautical Navigation Products (AeroNav Products) that include DPs, STARs, IAPs, and other information pertinent to IFR flight.
Unusual attitude. An unintentional, unanticipated, or extreme aircraft attitude.
Useful load. The weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation aircraft only.
User-defined waypoints. Waypoint location and other data which may be input by the user, this is the only GPS database information that may be altered (edited) by the user.
V
V1. See takeoff decision speed.
V2. See takeoff safety speed.
VA. See maneuvering speed.
Vapor lock. A problem that mostly affects gasoline-fuelled internal combustion engines. It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, resulting in transient loss of power or complete stalling. Restarting the engine from this state may be difficult. The fuel can vaporize due to being heated by the engine, by the local climate or due to a lower boiling point at high altitude.
Variation. Compass error caused by the difference in the physical locations of the magnetic north pole and the geographic north pole.
VASI. See visual approach slope indicator.
VDP. See visual descent point.
Vector. A force vector is a graphic representation of a force and shows both the magnitude and direction of the force.
Vectoring. Navigational guidance by assigning headings.
VEF. Calibrated airspeed at which the critical engine of a multi-engine aircraft is assumed to fail.
Velocity. The speed or rate of movement in a certain direction.
Venturi tube. A specially shaped tube attached to the outside of an aircraft to produce suction to allow proper operation of gyro instruments.
Vertical axis. An imaginary line passing vertically through the center of gravity of an aircraft. The vertical axis is called the z-axis or the yaw axis.
Vertical card compass. A magnetic compass that consists of an azimuth on a vertical card, resembling a heading indicator with a fixed miniature airplane to accurately present the heading of the aircraft. The design uses eddy current damping to minimize lead and lag during turns.
Vertical speed indicator (VSI). A rate-of-pressure change instrument that gives an indication of any deviation from a constant pressure level.
Vertical stability. Stability about an aircraft’s vertical axis. Also called yawing or directional stability.
Very-high frequency (VHF). A band of radio frequencies falling between 30 and 300 MHz.
Very-high frequency omnidirectional range (VOR). Electronic navigation equipment in which the flight deck instrument identifies the radial or line from the VOR station, measured in degrees clockwise from magnetic north, along which the aircraft is located.
Vestibule. The central cavity of the bony labyrinth of the ear, or the parts of the membranous labyrinth that it contains.
VFE. The maximum speed with the flaps extended. The upper limit of the white arc.
VFR. See visual flight rules.
VFR on top. ATC authorization for an IFR aircraft to operate in VFR conditions at any appropriate VFR altitude.
VFR over the top. A VFR operation in which an aircraft operates in VFR conditions on top of an undercast.
VFR terminal area chart. At a scale of 1:250,000, a chart that depicts Class B airspace, which provides for the control or segregation of all the aircraft within the Class B airspace. The chart depicts topographic information and aeronautical information including visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.
V-G diagram. A chart that relates velocity to load factor. It is valid only for a specific weight, configuration and altitude and shows the maximum amount of positive or negative lift
the airplane is capable of generating at a given speed. Also shows the safe load factor limits and the load factor that the aircraft can sustain at various speeds.
Victor airways. Airways based on a centerline that extends from one VOR or VORTAC navigation aid or intersection, to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas.
Visual approach slope indicator (VASI). A visual aid of lights arranged to provide descent guidance information during the approach to the runway. A pilot on the correct glideslope will see red lights over white lights.
Visual descent point (VDP). A defined point on the final approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the runway environment is clearly visible to the pilot.
Visual flight rules (VFR). Flight rules adopted by the FAA governing aircraft flight using visual references. VFR operations specify the amount of ceiling and the visibility the pilot must have in order to operate according to these rules. When the weather conditions are such that the pilot cannot operate according to VFR, he or she must use instrument flight rules (IFR).
Visual meteorological conditions (VMC). Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.
VLE. Landing gear extended speed. The maximum speed at which an airplane can be safely flown with the landing gear extended.
VLO. Landing gear operating speed. The maximum speed for extending or retracting the landing gear if using an airplane equipped with retractable landing gear.
VMC. Minimum control airspeed. This is the minimum flight speed at which a light, twin-engine airplane can be satisfactorily controlled when an engine suddenly becomes inoperative and the remaining engine is at takeoff power.
VMC. See visual meteorological conditions.
VNE. The never-exceed speed. Operating above this speed is prohibited since it may result in damage or structural failure. The red line on the airspeed indicator.
VNO. The maximum structural cruising speed. Do not exceed this speed except in smooth air. The upper limit of the green arc.
Pilot's Handbook of Aeronautical Knowledge (Federal Aviation Administration) Page 86
