Pilot/Controller Glossary 

12/2/21 

VMC

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(See VISUAL METEOROLOGICAL 

CONDITIONS.) 

VOICE SWITCHING AND CONTROL SYSTEM 
(VSCS)

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 A computer controlled switching system 

that provides air traffic controllers with all voice 
circuits (air to ground and ground to ground) 
necessary for air traffic control. 

(Refer to AIM.) 

VOR

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  A ground-based electronic navigation aid 

transmitting very high frequency navigation signals, 
360 degrees in azimuth, oriented from magnetic 
north. Used as the basis for navigation in the National 
Airspace System. The VOR periodically identifies 
itself by Morse Code and may have an additional 
voice identification feature. Voice features may be 
used by ATC or FSS for transmitting instructions/in-
formation to pilots. 

(See NAVIGATIONAL AID.) 
(Refer to AIM.) 

VOR TEST SIGNAL

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(See VOT.) 

VORTAC

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 A navigation aid providing VOR 

azimuth, TACAN azimuth, and TACAN distance 
measuring equipment (DME) at one site. 

(See DISTANCE MEASURING EQUIPMENT.) 
(See NAVIGATIONAL AID.) 
(See TACAN.) 
(See VOR.) 
(Refer to AIM.) 

VORTICES

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 Circular patterns of air created by the 

movement of an airfoil through the air when 
generating lift. As an airfoil moves through the 
atmosphere in sustained flight, an area of area of low 
pressure is created above it. The air flowing from the 
high pressure area to the low pressure area around and 
about the tips of the airfoil tends to roll up into two 
rapidly rotating vortices, cylindrical in shape. These 
vortices are the most predominant parts of aircraft 
wake turbulence and their rotational force is 
dependent upon the wing loading, gross weight, and 
speed of the generating aircraft. The vortices from 
medium to super aircraft can be of extremely high 
velocity and hazardous to smaller aircraft. 

(See AIRCRAFT CLASSES.) 
(See WAKE TURBULENCE.) 
(Refer to AIM.) 

VOT

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 A ground facility which emits a test signal to 

check VOR receiver accuracy. Some VOTs are 
available to the user while airborne, and others are 
limited to ground use only. 

(See CHART SUPPLEMENT U.S.) 
(Refer to 14 CFR Part 91.) 
(Refer to AIM.) 

VR

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(See VFR MILITARY TRAINING ROUTES.) 

VSCS

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(See VOICE SWITCHING AND CONTROL 

SYSTEM.) 

VTOL AIRCRAFT

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(See VERTICAL TAKEOFF AND LANDING 

AIRCRAFT.) 

PCG V

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