THERMAL—A buoyant plume or bubble of rising  air. THROTTLE—The control in an aircraft that regu- lates the power or thrust the pilot wants the engine  to develop. STEERING LINES—Connected to the steering bars  and routed through pulleys up to the trailing edge  of the parachute. STRAIGHT-IN APPROACH—Entry into the traffic  pattern by interception of the extended runway  centerline (final approach course) without execut- ing any other portion of the traffic pattern. STRESS MANAGEMENT—The personal analysis  of the kinds of stress experienced while flying, the  application of appropriate stress assessment tools,  and other coping mechanisms. STROBE—A high intensity white flashing light.  Strobe lights are located on aircraft wingtips to  increase aircraft visibility in low light conditions. THRUST—The force which imparts a change in the  velocity of a mass. A forward force which propels  the powered parachute through the air. TORQUE—(1) A resistance to turning or twisting.  (2) Forces that produce a twisting or rotating mo- tion. (3) In a PPC, the tendency of the aircraft to  turn (roll) in the opposite direction of rotation of  the engine and propeller. TOTAL DRAG—The sum of the parasite and in- duced drag. TOUCH AND GO—An operation by an aircraft that  lands and takes off without stopping. TOUCHDOWN POINT—The point or intended  point at which an aircraft first makes contact with  the landing surface. STUDENT PILOT CERTIFICATE— An FAA-  issued certificate that permits student pilots to  exercise solo pilot privileges with limitations. A student’s medical becomes their student pilot  certificate once it is endorsed by their flight instructor. TOUCHDOWN ZONE—The portion of a runway,  beyond the threshold, where it is intended landing  aircraft first contact the runway. TRACK—The actual path made over the ground in  flight. SUSPENSION LINES—Lines that run from several  attachment points on the wing down to a set of  cables called risers, which connect to the PPC cart. TRAFFIC PATTERN—The traffic flow that is pre- scribed for aircraft landing at or taking off from an  airport. TRAFFIC PATTERN INDICATORS—Ground  based visual indicators that identify traffic pattern  direction at certain airports. TRAILING EDGE—The portion of the airfoil where  the airflow over the upper surface rejoins the lower  surface airflow. TRANSPONDER—The airborne portion of the sec- ondary surveillance radar system. The transponder  emits a reply when queried by a radar facility. TRICYCLE GEAR CONFIGURATION—Land- ing gear configuration employing a third wheel  located on the nose of the aircraft. TAILWIND—Wind blowing in the same direction  the aircraft is moving. When an aircraft is flying  with a tailwind, its speed over the ground is equal  to its speed through the air, plus the speed the air  is moving over the ground. TAKEOFF CLEARANCE—ATC authorization for  an aircraft to depart a runway. It is predicated on  known traffic and known physical airport condi- tions. TAXI—The movement of an aircraft under its own  power while on the ground. TAXIWAY—Airport area designated for aircraft  surface movement. TEMPORARY FLIGHT RESTRICTION (TFR)— Designated airspace of specified dimension where  flight is temporarily restricted or prohibited.  NOTAMs are issued to advise airmen of local TFR  restrictions. TRSA—See TERMINAL RADAR SERVICE AREAS. TWO-STROKE ENGINE—A simple form of  reciprocating engine that completes its operating  cycle in two strokes of its piston—one down and  one up. Two-stroke-cycle engines are inefficient  in their use of fuel, but their simplicity makes  them popular for powering light-sport aircraft and  ultralight vehicles where light weight and low cost  are paramount. TERMINAL RADAR SERVICE AREAS (TRSA)— Areas where participating pilots can receive addi- tional radar services. The purpose of the service is  to provide separation between all IFR operations  and participating VFR aircraft. TFR—See TEMPORARY FLIGHT RESTRIC- TION. G-10 the steering bars move forward and back when the  pilot applies foot pressure. Pushing either one of  the steering bars causes the steering lines to pull  down on the corresponding surface of the trailing  edge on the wing which banks the PPC into a turn.