Pilot/Controller Glossary Pilot/Controller Glossary  8/15/19 1/30/20  T  TACAN - (See TACTICAL AIR NAVIGATION.)  TACAN-ONLY AIRCRAFT- An aircraft, normally  military, possessing TACAN with DME but no VOR  navigational system capability. Clearances must  specify TACAN or VORTAC fixes and approaches.  TACTICAL AIR NAVIGATION (TCAN)- An  ultra-high frequency electronic rho-theta air naviga- tion aid which provides suitably equipped aircraft a  continuous indication of bearing and distance to the  TACAN station.  (See VORTAC.)  (Refer to AIM.)  TAILWIND- Any wind more than 90 degrees to the  longitudinal axis of the runway. The magnetic  direction of the runway shall be used as the basis for  determining the longitudinal axis.  TAKEOFF AREA - (See LANDING AREA.)  TAKEOFF DISTANCE AVAILABLE (TODA)– The  takeoff run available plus the length of any remaining  runway or clearway beyond the far end of the takeoff  run available.  (See ICAO term TAKEOFF DISTANCE  AVAILABLE.)  TAKEOFF DISTANCE AVAILABLE [ICAO]- The  length of the takeoff run available plus the length of  the clearway, if provided.  TAKEOFF HOLD LIGHTS (THL)– The THL  system is composed of in-pavement lighting in a  double, longitudinal row of lights aligned either side  of the runway centerline. The lights are focused  toward the arrival end of the runway at the “line up  and wait” point, and they extend for 1,500 feet in  front of the holding aircraft. Illuminated red lights  indicate to an aircraft in position for takeoff or rolling  that it is unsafe to takeoff because the runway is  occupied or about to be occupied by an aircraft or  vehicle.  TAKEOFF ROLL - The process whereby an aircraft  is aligned with the runway centerline and the aircraft  is moving with the intent to take off. For helicopters,  this pertains to the act of becoming airborne after  departing a takeoff area.  TAKEOFF RUN AVAILABLE (TORA) – The  runway length declared available and suitable for the  ground run of an airplane taking off.  (See ICAO term TAKEOFF RUN AVAILABLE.)  TAKEOFF RUN AVAILABLE [ICAO]- The length  of runway declared available and suitable for the  ground run of an aeroplane take-off.  TARGET- The indication shown on a display  resulting from a primary radar return, a radar beacon  reply, or an ADS-B report. The specific target  symbol presented to ATC may vary based on the  surveillance source and automation platform.  (See ASSOCIATED.)  (See DIGITAL TARGET.)  (See DIGITIZED RADAR TARGET.)  (See FUSED TARGET.)  (See PRIMARY RADAR TARGET.)  (See RADAR.)  (See SECONDARY RADAR TARGET.)  (See ICAO term TARGET.)  (See UNASSOCIATED.)  TARGET [ICAO]- In radar:  a.  Generally, any discrete object which reflects or  retransmits energy back to the radar equipment.  b.  Specifically, an object of radar search or  surveillance.  TARGET RESOLUTION- A process to ensure that  correlated radar targets do not touch. Target  resolution must be applied as follows:  a.  Between the edges of two primary targets or the  edges of the ASR-9/11 primary target symbol.  b.  Between the end of the beacon control slash and  the edge of a primary target.  c.  Between the ends of two beacon control slashes.  Note 1: Mandatory traffic advisories and safety  alerts must be issued when this procedure is used.  Note 2: This procedure must not be used when  utilizing mosaic radar systems or multi-sensor  mode.  TARGET SYMBOL- (See TARGET.)  (See ICAO term TARGET.) 