Glossary

Torquemeter. An instrument used with some of the larger Transponder code. One of 4,096 four-digit discrete codes reciprocating engines and turboprop or turboshaft engines to ATC assigns to distinguish between aircraft. measure the reaction between the propeller reduction gears and the engine case. Trend. Immediate indication of the direction of aircraft movement, as shown on instruments. Total drag. The sum of the parasite drag and induced drag. Tricycle gear. Landing gear employing a third wheel located Touchdown zone elevation (TDZE). The highest elevation on the nose of the aircraft. in the first 3,000 feet of the landing surface, TDZE is indicated on the instrument approach procedure chart when Trim. To adjust the aerodynamic forces on the control straight-in landing minimums are authorized. surfaces so that the aircraft maintains the set attitude without any control input. Touchdown zone lights. Two rows of transverse light bars disposed symmetrically about the runway centerline in the Trim tab. A small auxiliary hinged portion of a movable runway touchdown zone. control surface that can be adjusted during flight to a position resulting in a balance of control forces. Tower En Route Control (TEC). The control of IFR en route traffic within delegated airspace between two Tropopause. The boundary layer between the troposphere or more adjacent approach control facilities, designed to and the stratosphere which acts as a lid to confine most of the expedite traffic and reduce control and pilot communication water vapor, and the associated weather, to the troposphere. requirements. Troposphere. The layer of the atmosphere extending from TPP. See United States Terminal Procedures Publication. the surface to a height of 20,000 to 60,000 feet, depending on latitude. Track. The actual path made over the ground in flight. True airspeed. Actual airspeed, determined by applying a Tracking. Flying a heading that will maintain the desired correction for pressure altitude and temperature to the CAS. track to or from the station regardless of crosswind conditions. True altitude. The vertical distance of the airplane above Traffic Alert Collision Avoidance System (TCAS). sea level—the actual altitude. It is often expressed as feet An airborne system developed by the FAA that operates above mean sea level (MSL). Airport, terrain, and obstacle independently from the ground-based Air Traffic Control elevations on aeronautical charts are true altitudes. system. Designed to increase flight deck awareness of proximate aircraft and to serve as a “last line of defense” for Truss. A fuselage design made up of supporting structural the prevention of midair collisions. members that resist deformation by applied loads. The truss- type fuselage is constructed of steel or aluminum tubing. Traffic information service (TIS). A ground-based service Strength and rigidity is achieved by welding the tubing providing information to the flight deck via data link using together into a series of triangular shapes, called trusses. the S-mode transponder and altitude encoder to improve the safety and efficiency of “see and avoid” flight through an T-tail. An aircraft with the horizontal stabilizer mounted on automatic display that informs the pilot of nearby traffic. the top of the vertical stabilizer, forming a T. Trailing edge. The portion of the airfoil where the airflow Turbine discharge pressure. The total pressure at the over the upper surface rejoins the lower surface airflow. discharge of the low-pressure turbine in a dual-turbine axial- flow engine. Transcribed Weather Broadcast (TWEB). An FSS service, available in Alaska only, providing continuously updated Turbine engine. An aircraft engine which consists of an automated broadcast of meteorological and aeronautical data air compressor, a combustion section, and a turbine. Thrust over selected L/MF and VOR NAVAIDs. is produced by increasing the velocity of the air flowing through the engine. Transponder. The airborne portion of the ATC radar beacon system. G-31