Glossary - T

TA.   See traffic advisory.

Tape display.   A vertical display format used to portray, for example, airspeed and altitude on many primary flight displays. Also used for vertical speeds and many other value displays such as power settings and powerplant speeds.

TAWS.   See terrain awareness and warning system.

TCAS.   See Traffic Alert and Collision Avoidance System.

Terminal Arrival Area.   The published or assigned track by which aircraft are transitioned from the en route structure to the terminal area. A terminal arrival area consists of a designated volume of airspace designed to allow aircraft to enter a protected area with obstacle clearance and signal reception guaranteed where the initial approach course is intercepted.

Terminal mode.   One name used for the FMS/RNAV sensitivity mode in which the aircraft is operating within 30 NM of an airport. In terminal mode, the required navigation performance sensitivity of the course deviation indicator becomes 1 NM. Also called approach arm mode.

Terrain and obstacle database.   An electronic database storing details of the significant terrain features and obstacles that could potentially pose a threat to aircraft flight. Some obstructions, especially manmade, may not be in the database, even if it is current. Do not plan a flight based on dependence on the database to keep the aircraft clear of obstacles and obstructions to navigation.

Terrain Awareness and Warning System (TAWS).   An onboard system that can alert the pilot to a number of potential hazards presented by proximate terrain such as excessive rate of descent, excessive closure rate to terrain, and altitude loss after takeoff.

Terrain display.   A pictorial display that shows surrounding terrain and obstacles that present a potential threat to your aircraft, given your present altitude. Draws terrain information from a terrain and obstacle database.

Terrain inhibit switch.   A switch that allows the pilot to suppress all visual and auditory warnings given by a terrain system. Often used to silence nuisance alerts when in deliberate operation in the vicinity of terrain.

Terrain system.   Any cockpit system that provides the pilot with a pictorial view of surrounding terrain, and in some cases, visual and/or auditory alerts when the aircraft is operating in close proximity to terrain.

TIS.   See traffic information service.

Top-of-descent point.   The point that the RNAV computer calculates to be the ideal location at which to begin a descent to the planned crossing restriction, given the descent speed and rate that has been entered by the pilot.

Topographical database.   A volume of information stored in an advanced cockpit system that details the topographical features of the earth’s surface. Used by several systems to assess aircraft position and altitude with respect to surrounding terrain.

Traffic Advisory (TA).   A warning issued by a traffic system that alerts the pilot to other aircraft that have moved within a prescribed “safety zone” that surrounds the aircraft.

Traffic Alert and Collision Avoidance System.   An onboard system that detects the presence of some aircraft operating in the vicinity of the airplane by querying the transponders of nearby aircraft and presenting their locations and relative altitudes on a display. Alerts and warnings are issued when nearby aircraft are deemed to be a threat to safety. Traffic advisory systems such as ADS-B are an offshoot of newer technologies, but do not yet offer the reliability or accuracy of proven, certified TCAS units.

Traffic data system.   An advanced avionics system designed to aid the pilot in visually acquiring and maintaining awareness of nearby aircraft that pose potential collision threats.

Traffic display.   A pictorial display showing any aircraft operating in the vicinity that have been detected by a traffic data system.

Traffic Information Service (TIS).   A groundbased advanced avionics traffic display system which receives transmissions on locations of nearby aircraft from radarequipped air traffic control facilities and provides alerts and warnings to the pilot.

Turn anticipation.   The function performed by FMS/ RNAV units to advise the pilot when to begin a turn to the next waypoint in the programmed flight route to avoid overshooting the programmed track.

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