PCG UDF -- UVDF
UDF -- UVDF
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
(See ULTRAHIGH FREQUENCY.)
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
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.
UNPUBLISHED ROUTE- A route for which no minimum altitude is published or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.
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
(See AIRPORT/FACILITY DIRECTORY.)
(See ARMY AVIATION FLIGHT INFORMATION BULLETIN.)