Glossary of Aviation Terminology |

**Velocity: **Rate of change of location, either scalar or vector, often with subscripts such as ENU or XYZ to denote the coordinate frame; time derivative of position; time integral of acceleration; Symbols: v,V; Typical Units: kt,ft/s; Dimensions: Length / Time;

**Velocity east:** Aircraft velocity in true east direction; Symbols: V sub E; Typical Units: kt, ft/s; Dimensions: Length / Time;

**Velocity error scale factor (KVSF): **A guidance control law parameter, generated by the longitudinal guidance modes;

**Velocity north: **Aircraft velocity in true north direction; Symbols: V sub N; Typical Units: kt,ft/s; Dimensions: Length / Time;

**VERT SPD: **Vertical speed hold

**Vertical: **Reference to earth radial, for example, vertical velocity is velocity along earth radial; See Also: East-North-Vertical;

**Vertical acceleration:** Aircraft acceleration in earth vertical direction; Symbols: A sub V; Typical Units: ft/s-squared,g; Dimensions: Length / Time-squared;

**Vertical cue:** A cue to control altitude; See Also: yoke cue, collective cue;

**Vertical guidance: **Calculations for the vertical axis, rather than the longitudinal axis. The control law vertical axis input data are: Desired Altitude, Altitude Integral, Altitude Integral Gain, Altitude Integral Limit, Altitude Error Scale Factor, Magnitude limit for delta altitudes. The major output from Vertical Guidance is the altitude error for the selected vertical guidance mode.

**Vertical speed hold (VERT SPD):** A basic guidance mode, providing vertical guidance to maintain an operator selected vertical speed;

**Vertical velocity: **Aircraft velocity in earth vertical direction; Symbols: V sub V; Typical Units: ft/s; Dimensions: Length / Time;

**VHF Omnirange (VOR):** Equipment that determines bearing to a radio station with a VOR transmitter; VOR transmitters usually contain ILS transmitters in addition to VOR; A basic guidance mode, providing lateral guidance to a VOR station. A VOR/ILS/MB. radio receiver provides a VHF Omni-Direction Range (VOR) function and Instrument Landing System with Marker Beacon (MB) function. VOR provides bearings to a fixed point (Localizer function); ILS/MB provides course (localizer function) and glideslope deviations (Glide Slope (G/S) function) during approach to a runway, along with marker beacon indications. If VOR is collocated with a TACAN (VOR-TAC, or VORTAC), bearing and range information is provided.

**VOR:** VHF Omnirange;

**VORTAC:** Collocation of VOR and TACAN providing distance and bearing to station; a basic guidance mode, providing lateral guidance to a set of a VOR station and a TACAN station that are collocated