Order 7110.65P, Air Traffic Control, with changes

2/19/04Pilot/Controller GlossaryBBACK-TAXI− A term used by air traffic controllersto taxi an aircraft on the runway opposite to the trafficflow. The aircraft may be instructed to back-taxi tothe beginning of the runway or at some point beforereaching the runway end for the purpose of departureor to exit the runway.BASE LEG−(See TRAFFIC PATTERN.)BEACON−(See AERONAUTICAL BEACON.)(See AIRPORT ROTATING BEACON.)(See AIRWAY BEACON.)(See MARKER BEACON.)(See NONDIRECTIONAL BEACON.)(See RADAR.)BEARING− The horizontal direction to or from anypoint, usually measured clockwise from true north,magnetic north, or some other reference pointthrough 360 degrees.(See NONDIRECTIONAL BEACON.)BELOW MINIMUMS− Weather conditions belowthe minimums prescribed by regulation for theparticular action involved; e.g., landing minimums,takeoff minimums.BLAST FENCE− A barrier that is used to divert ordissipate jet or propeller blast.BLIND SPEED− The rate of departure or closing ofa target relative to the radar antenna at whichcancellation of the primary radar target by movingtarget indicator (MTI) circuits in the radar equipmentcauses a reduction or complete loss of signal.(See ICAO term BLIND VELOCITY.)BLIND SPOT− An area from which radio transmissionsand/or radar echoes cannot be received. Theterm is also used to describe portions of the airport notvisible from the control tower.BLIND TRANSMISSION−(See TRANSMITTING IN THE BLIND.)BLIND VELOCITY [ICAO]− The radial velocity ofa moving target such that the target is not seen onprimary radars fitted with certain forms of fixed echosuppression.BLIND ZONE−(See BLIND SPOT.)BLOCKED− Phraseology used to indicate that aradio transmission has been distorted or interrupteddue to multiple simultaneous radio transmissions.BOUNDARY LIGHTS−(See AIRPORT LIGHTING.)BRAKING ACTION (GOOD, FAIR, POOR, ORNIL)− A report of conditions on the airport movementarea providing a pilot with a degree/quality ofbraking that he/she might expect. Braking action isreported in terms of good, fair, poor, or nil.(See RUNWAY CONDITION READING.)BRAKING ACTION ADVISORIES− When towercontrollers have received runway braking actionreports which include the terms “poor” or “nil,” orwhenever weather conditions are conducive to deterioratingor rapidly changing runway braking conditions,the tower will include on the ATIS broadcastthe statement, “BRAKING ACTION ADVISORIESARE IN EFFECT.” During the time Braking ActionAdvisories are in effect, ATC will issue the latestbraking action report for the runway in use to eacharriving and departing aircraft. Pilots should beprepared for deteriorating braking conditions andshould request current runway condition informationif not volunteered by controllers. Pilots should alsobe prepared to provide a descriptive runway conditionreport to controllers after landing.BREAKOUT− A technique to direct aircraft out ofthe approach stream. In the context of close paralleloperations, a breakout is used to direct threatenedaircraft away from a deviating aircraft.BROADCAST− Transmission of information forwhich an acknowledgement is not expected.(See ICAO term BROADCAST.)BROADCAST [ICAO]− A transmission of informationrelating to air navigation that is not addressed toa specific station or stations.PCG B−1