V speeds - designations for certain velocities relating to
aircraft operation, thus:
V1 - decision speed, up to which it should be possible to abort
a take-off and
stop safely within the remaining runway length. After
reaching V1 the take-off
must be continued.
Va - design manoeuvring speed. The speed below which abrupt and
control movements are possible (though not advised) without
airframe's limiting load factors.
Vfe - maximum flap extension speed (top of white arc on ASI).
Vmca - minimum control speed (air). The minimum speed at which
control of a
twin-engined aircraft can be maintained after failure
of one engine.
Vmo - maximum operating speed. Also Mmo, Mach limit maximum
Vne - never-exceed speed, 'redline speed' denoted by a red
radial on an ASI.
Vno - normal operating speed. The maximum structural cruising
speed allowable for normal operating conditions (top of green arc on ASI).
Vr - rotation speed, at which to raise the nose for take-off.
Vso stalling speed
at MTWA, in landing configuration with flaps and
landing gear down, at sea level,
Vx - best angle of climb speed on all engines.
Vxse - best engine-out angle of climb speed.
Vy - best rate of climb speed on all engines.
Vyse - best engine-out rate of climb speed, 'blueline speed'
(blue radial on ASIs of light twins)
VAL - design manoeuvring speed. The speed below which abrupt
control movements are possible (though not advised)
without exceeding the airframe's limiting load factors.
VAL - visual approach and landing chart.
var - variation (magnetic)
VASIS - visual approach slope indicator system. A coloured
light system providing
visual guidance to the glidepath of a runway.
VDF - very-high frequency direction-finding, whereby an
aircraft's bearing from a
ground receiving station may be determined
from its RT transmissions.
vdu - visual display unit.
VFR - Visual Flight Rules. Prescribed for the operation of
aircraft in visual meteorological
conditions (VMC).VMC is generally
defined as five miles visibility or more and 1,000 feet
one nautical mile horizontal clearance from cloud, but variations
aircraft operating below 3,000 feet amsl. Special VFR (SVFR)
clearances are granted at
the discretion of ATC for VFR flight through
some controlled airspace where IFR usually apply.
Controlled VFR Flight.
VHF - very high frequency. Radio frequencies in the 30-300 MHz
band, used for most civil
vis - visibility.
VLF - very low frequency. Radio frequencies in the 3-30 kHz
VLF/Omega - worldwide system of long-range navigation using VLF
VMC - Visual Meterorological Conditions. See VFR, above.
Vnav - vertical navigation.
Volmet - continuous recorded broadcasts of weather conditions
at selected airfields.
VOR - very high frequency omnidirectional range. A radio
navigation aid operating in
the 108-118 MHz band. A VOR ground station
transmits a two-phase directional signal
through 360ø. the aircraft's VOR receiver enables a pilot to identify his radial or bearing
the ground station. VOR is the most commonly used radio navigation aid
flying. Increased accuracy is available in Doppler VORs (DVOR)
which have replaced
some VOR is the UK system. Also VORTAC, combined
VOR and TACAN, and VOT, VOR test facility.
VP - variable-pitch (propeller), whose blade angle can be
altered in flight either automatically
VRP - visual reference point. (In the UK) Landmarks used for
position reporting by aircraft
VSI - vertical speed indicator. One of the primary flight
instruments showing rate of climb or
descent. Also IVSI, instantaneous