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.
(See FAR Part 103.)
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.
(Refer to FAR Part 91.)
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.)
(Refer to AIM.)
UNPUBLISHED ROUTE- A route for which no minimum altitude is published or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.
(See PUBLISHED ROUTE.)
(See ROUTE.)
UPWIND LEG-
(See TRAFFIC PATTERN.)
URGENCY- A condition of being concerned about safety and of requiring timely
but not immediate assistance; a potential distress condition.
(See ICAO term URGENCY.)
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.
