touchdown zone (air traffic control). The first 3,000 feet of a runway beginning at the threshold. This area is used for determining the touchdown zone elevation in the development of straight-in landing minimums for instrument approaches.
toughness (material characteristic). The characteristic of a material that allows it to be deformed by twisting, pulling, hammering, or bending without its breaking.
towering cumulus (meteorology). A rapidly growing cumulus cloud in which its height is greater than its width.
tower visibility (meteorology). Prevailing visibility as determined from an airport control tower.
towing eye (aircraft structural component). A ring, usually installed on some strong part of the landing gear of an aircraft, to which a tow bar or cable can be attached to move the aircraft on the ground.
Townend ring (aircraft component). A type of ring cowling used over a single-row radial engine. The Townend ring, often called a speed ring, directs the air smoothly over the cylinder heads to increase the cooling and decrease the drag.
tower (air traffic control facility). A terminal facility that uses air/ground communications, visual signaling, and other devices to provide ATC services to aircraft operating in the vicinity of the airport or on the movement area. Tower controllers authorize aircraft to land or takeoff at the airport or to transit the Class D airspace regardless of flight plan or weather conditions. A tower may also provide approach control services.
TPX-42 (air traffic control equipment). A numeric beacon decoder equipment/system, designed to be added to terminal radar systems for beacon decoding. TPX-42 provides rapid target identification, reinforcement of the primary radar target, and altitude information from Mode C.
traffic pattern. The traffic flow that is prescribed for aircraft landing at, taxiing on, or taking off from an airport. The components of a typical traffic pattern are: upwind leg, crosswind leg, downwind leg, base leg, and final approach.
T/R. (transformer/rectifier). A component in a large aircraft electrical system used to reduce the AC voltage and change it into DC for charging the battery and operating DC equipment in the aircraft.
track (helicopter rotor blade condition). The path followed by the blade tips of a helicopter rotor as they rotate.
track (propeller). The path followed by a blade segment of a propeller in one rotation.
tracking flag (helicopter maintenance tool). A white cotton flag mounted in line with a wooden pole and attached at both ends. Colored transfer marks are made on the blade tips, and the tracking flag is carefully moved against the tips of the blades as the helicopter is held near a hover. The colored chalk transfers to the tracking flag to show the relative vertical position of the blade tips as they rotate.
tracking reflectors (helicopter maintenance tool). Small colored reflectors installed on the tip of a helicopter rotor to aid in checking the track of the blades. A spotlight is shone on the tip of the rotor, and as it reflects off the reflectors, it shows up as bars of colored light. The bars caused by both reflectors must be superimposed for the rotor blades to be in track.
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