UDF -- UVDF
UDF-
UHF-
(See ULTRAHIGH FREQUENCY.)
ULTRAHIGH FREQUENCY- The frequency band
between 300 and 3,000 mHz. The bank of radio frequencies used for military
air/ground voice communications. In some instances this may go as low as 225 mHz
and still be referred to as UHF.
ULTRALIGHT VEHICLE- An aeronautical vehicle operated for sport or
recreational purposes which does not require FAA registration, an airworthiness
certificate, nor pilot certification. They are primarily single occupant
vehicles, although some two-place vehicles are authorized for training purposes.
Operation of an ultralight vehicle in certain airspace requires authorization
from ATC.
UNABLE- Indicates inability to
comply with a specific instruction, request, or clearance.
UNDER THE HOOD- Indicates that the pilot is using a hood to restrict
visibility outside the cockpit while simulating instrument flight. An
appropriately rated pilot is required in the other control seat while this
operation is being conducted.
UNICOM- A nongovernment communication
facility which may provide airport information at certain airports. Locations
and frequencies of UNICOM's are shown on aeronautical charts and publications.
(See AIRPORT/FACILITY DIRECTORY.)
UNPUBLISHED ROUTE- A route for which no minimum
altitude is published or charted for pilot use. It may include a direct route
between NAVAID's, a radial, a radar vector, or a final approach course beyond
the segments of an instrument approach procedure.
UPWIND LEG-
URGENCY- A condition of being concerned
about safety and of requiring timely but not immediate assistance; a potential
distress condition.
URGENCY [ICAO]- A condition concerning the
safety of an aircraft or other vehicle, or of person on board or in sight, but
which does not require immediate assistance.
USAFIB-
(See ARMY AVIATION FLIGHT INFORMATION BULLETIN.)
UVDF-