Pilot/Controller Glossary Pilot/Controller Glossary  8/15/19 12/31/20  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.  a.  Upwind Leg- A flight path parallel to the  landing runway in the direction of landing.  b.  Crosswind Leg- A flight path at right angles to  the landing runway off its upwind end.  c.  Downwind Leg- A flight path parallel to the  landing runway in the direction opposite to landing.  The downwind leg normally extends between the  crosswind leg and the base leg.  d.  Base Leg- A flight path at right angles to the  landing runway off its approach end. The base leg  normally extends from the downwind leg to the  intersection of the extended runway centerline.  e.  Final Approach- A flight path in the direction  of landing along the extended runway centerline. The  final approach normally extends from the base leg to  the runway. An aircraft making a straight-in approach  VFR is also considered to be on final approach.  (See STRAIGHT-IN APPROACH VFR.)  (See TAXI PATTERNS.)  (See ICAO term AERODROME TRAFFIC  CIRCUIT.)  (Refer to 14 CFR Part 91.)  (Refer to AIM.)  TRAFFIC SITUATION DISPLAY (TSD)- TSD is a  computer system that receives radar track data from  all 20 CONUS ARTCCs, organizes this data into a  mosaic display, and presents it on a computer screen.  The display allows the traffic management coordina- tor multiple methods of selection and highlighting of  individual aircraft or groups of aircraft. The user has  the option of superimposing these aircraft positions  over any number of background displays. These  background options include ARTCC boundaries, any  stratum of en route sector boundaries, fixes, airways,  military and other special use airspace, airports, and  geopolitical boundaries. By using the TSD, a  coordinator can monitor any number of traffic  situations or the entire systemwide traffic flows.  TRAJECTORY- A EDST representation of the path  an aircraft is predicted to fly based upon a Current  Plan or Trial Plan.  (See EN ROUTE DECISION SUPPORT TOOL.)  TRAJECTORY MODELING- The automated pro- cess of calculating a trajectory.  TRAJECTORY OPTIONS SET (TOS)- A TOS is an  electronic message, submitted by the operator, that is  used by the Collaborative Trajectory Options  Program (CTOP) to manage the airspace captured in  the traffic management program. The TOS will allow  the operator to express the route and delay trade-off  options that they are willing to accept.  TRANSFER OF CONTROL- That action whereby  the responsibility for the separation of an aircraft is  transferred from one controller to another.  (See ICAO term TRANSFER OF CONTROL.)  TRANSFER OF CONTROL [ICAO]- Transfer of  responsibility for providing air traffic control service.  TRANSFERRING CONTROLLER- A controller/  facility transferring control of an aircraft to another  controller/facility.  (See ICAO term TRANSFERRING  UNIT/CONTROLLER.)  TRANSFERRING FACILITY - (See TRANSFERRING CONTROLLER.)  TRANSFERRING UNIT/CONTROLLER [ICAO]- Air traffic control unit/air traffic controller in the  process of transferring the responsibility for  providing air traffic control service to an aircraft to  the next air traffic control unit/air traffic controller  along the route of flight.  Note: See definition of accepting unit/controller.  TRANSITION- a.  The general term that describes the change from  one phase of flight or flight condition to another; e.g.,  transition from en route flight to the approach or  transition from instrument flight to visual flight.  b.  A published procedure (DP Transition) used to  connect the basic DP to one of several en route  airways/jet routes, or a published procedure (STAR  Transition) used to connect one of several en route  airways/jet routes to the basic STAR.  (Refer to DP/STAR Charts.)  TRANSITION POINT- A point at an adapted  number of miles from the vertex at which an arrival  aircraft would normally commence descent from its  en route altitude. This is the first fix adapted on the  arrival speed segments.  PCG T-7 