Order 7110.65P, Air Traffic Control, with changes

Pilot/Controller Glossary 2/19/04circuits (air to ground and ground to ground)necessary for air traffic control.(See VOICE SWITCHING AND CONTROLSYSTEM.)(Refer to AIM.)VOR− A ground-based electronic navigation aidtransmitting very high frequency navigation signals,360 degrees in azimuth, oriented from magneticnorth. Used as the basis for navigation in the NationalAirspace System. The VOR periodically identifiesitself by Morse Code and may have an additionalvoice identification feature. Voice features may beused by ATC or FSS for transmitting instructions/informationto pilots.(See NAVIGATIONAL AID.)(Refer to AIM.)VOR TEST SIGNAL−(See VOT.)VORTAC− A navigation aid providing VOR azimuth,TACAN azimuth, and TACAN distance measuringequipment (DME) at one site.(See DISTANCE MEASURING EQUIPMENT.)(See NAVIGATIONAL AID.)(See TACAN.)(See VOR.)(Refer to AIM.)VORTICES− Circular patterns of air created by themovement of an airfoil through the air when generatinglift. As an airfoil moves through the atmospherein sustained flight, an area of area of low pressure iscreated above it. The air flowing from the highpressure area to the low pressure area around andabout the tips of the airfoil tends to roll up into tworapidly rotating vortices, cylindrical in shape. Thesevortices are the most predominant parts of aircraftwake turbulence and their rotational force is dependentupon the wing loading, gross weight, and speedof the generating aircraft. The vortices from mediumto heavy aircraft can be of extremely high velocityand hazardous to smaller aircraft.(See AIRCRAFT CLASSES.)(See WAKE TURBULENCE.)(Refer to AIM.)VOT− A ground facility which emits a test signal tocheck VOR receiver accuracy. Some VOTs areavailable to the user while airborne, and others arelimited to ground use only.(See AIRPORT/FACILITY DIRECTORY.)(Refer to 14 CFR Part 91.)(Refer to AIM.)VR−(See VFR MILITARY TRAINING ROUTES.)VSCS−(See VOICE SWITCHING AND CONTROLSYSTEM.)VTA−(See VERTEX TIME OF ARRIVAL.)VTOL AIRCRAFT−(See VERTICAL TAKEOFF AND LANDINGAIRCRAFT.)PCG V−4