Order 7110.65P, Air Traffic Control, with changes

Pilot/Controller Glossary 2/19/04VTA. These calculations start at the transition pointand use arrival speed segments to the vertex.DESIRED COURSE−a. True− A predetermined desired course directionto be followed (measured in degrees from true north).b. Magnetic− A predetermined desired coursedirection to be followed (measured in degrees fromlocal magnetic north).DESIRED TRACK− The planned or intended trackbetween two waypoints. It is measured in degreesfrom either magnetic or true north. The instantaneousangle may change from point to point along the greatcircle track between waypoints.DETRESFA (DISTRESS PHASE) [ICAO]− Thecode word used to designate an emergency phasewherein there is reasonable certainty that an aircraftand its occupants are threatened by grave andimminent danger or require immediate assistance.DEVIATIONS−a. A departure from a current clearance, such as anoff course maneuver to avoid weather or turbulence.b. Where specifically authorized in the CFRs andrequested by the pilot, ATC may permit pilots todeviate from certain regulations.(Refer to AIM.)DF−(See DIRECTION FINDER.)DF APPROACH PROCEDURE− Used under emergencyconditions where another instrument approachprocedure cannot be executed. DF guidance for aninstrument approach is given by ATC facilities withDF capability.(See DF GUIDANCE.)(See DIRECTION FINDER.)(Refer to AIM.)DF FIX− The geographical location of an aircraftobtained by one or more direction finders.(See DIRECTION FINDER.)DF GUIDANCE− Headings provided to aircraft byfacilities equipped with direction finding equipment.These headings, if followed, will lead the aircraft toa predetermined point such as the DF station or anairport. DF guidance is given to aircraft in distress orto other aircraft which request the service. PracticeDF guidance is provided when workload permits.(See DIRECTION FINDER.)(See DF FIX.)(Refer to AIM.)DF STEER−(See DF GUIDANCE.)DH−(See DECISION HEIGHT.)DH [ICAO]−(See ICAO Term DECISION ALTITUDE/DECISION HEIGHT.)DIRECT− Straight line flight between two navigationalaids, fixes, points, or any combination thereof.When used by pilots in describing off-airway routes,points defining direct route segments become compulsoryreporting points unless the aircraft is underradar contact.DIRECT ALTITUDE AND IDENTITY READ-OUT− The DAIR System is a modification to theAN/TPX-42 Interrogator System. The Navy has twoadaptations of the DAIR System-Carrier Air TrafficControl Direct Altitude and Identification ReadoutSystem for Aircraft Carriers and Radar Air TrafficControl Facility Direct Altitude and Identity ReadoutSystem for land-based terminal operations. TheDAIR detects, tracks, and predicts secondary radaraircraft targets. Targets are displayed by means ofcomputer-generated symbols and alphanumeric charactersdepicting flight identification, altitude, groundspeed, and flight plan data. The DAIR System iscapable of interfacing with ARTCCs.DIRECTION FINDER− A radio receiver equippedwith a directional sensing antenna used to takebearings on a radio transmitter. Specialized radiodirection finders are used in aircraft as air navigationaids. Others are ground-based, primarily to obtain a“fix” on a pilot requesting orientation assistance or tolocate downed aircraft. A location “fix” is establishedby the intersection of two or more bearing linesplotted on a navigational chart using either twoseparately located Direction Finders to obtain a fix onan aircraft or by a pilot plotting the bearing indicationsof his/her DF on two separately locatedground-based transmitters, both of which can beidentified on his/her chart. UDFs receive signals inthe ultra high frequency radio broadcast band; VDFsin the very high frequency band; and UVDFs in bothPCG D−2