Aeronautical Terms beginning with U
U.S.
United States
UA
Unmanned Aircraft
UAS
Unmanned Aircraft System
UAT
Universal Access Transceiver
UAV
Unmanned Aerial Vehicle
UFO
Unidentified Flying Object
UHF
Ultra-High Frequency.
UHF
Ultrahigh Frequency
Ultimate load factor
In stress analysis, the load that causes physical breakdown in an aircraft or aircraft component during a strength test, or the load that according to computations, should cause such a breakdown.
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.
Uncaging
Unlocking the gimbals of a gyroscopic instrument, making it susceptible to damage by abrupt flight maneuvers or rough handling.
Uncaging
Unlocking the gimbals of a gyroscopic instrument, making it susceptible to damage by abrupt flight maneuvers or rough handling.
Uncontrolled airspace
Class G airspace that has not been designated as Class A, B, C, D, or E. It is airspace in which air traffic control has no authority or responsibility to control air traffic; however, pilots should remember there are VFR minimums which apply to this airspace.
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.
Undercast
A cloud layer of ten-tenths (1.0) coverage (to the nearest tenth) as viewed from an observation point above the layer.
Underpower
Using less power than required for the purpose of achieving a faster rate of airspeed change.
Underpower
Using less power than required for the purpose of achieving a faster rate of airspeed change.
Understanding
A basic level of learning at which a student comprehends or grasps the nature or meaning of something.
Undrainable Oil
Oil that does not drain from an engine lubricating system when the aircraft is in the normal ground attitude and the drain valve is left open. The weight of the undrainable oil is part of the empty weight of the aircraft.
Unfeathering Accumulator
Tanks that hold oil under pressure which can be used to unfeather a propeller.
Unicom
A nongovernment communication facility which may provide airport information at certain airports. Locations and frequencies of UNICOMs are shown on aeronautical charts and publications.
United States
In a geographical sense means (1) the States, the District of Columbia, Puerto Rico, and the possessions, including the territorial waters, and (2) the airspace of those areas.
United States air carrier
A citizen of the United States who undertakes directly by lease, or other arrangement, to engage in air transportation.
United States Terminal Procedures Publication (TPP)
Booklets published in regional format by the NACO that include DPs, STARs, IAPs, and other information pertinent to IFR flight.
Unlimited ceiling
A clear sky or a sky cover that does not meet the criteria for a ceiling.
Unpublished Route
A route for which no minimum altitude is published or charted for pilot use. It may include a direct route between NAVAIDs, a radial, a radar vector, or a final approach course beyond the segments of an instrument approach procedure.
Unreliable (GPS/WAAS)
An advisory to pilots indicating the expected level of service of the GPS and/or WAAS may not be available. Pilots must then determine the adequacy of the signal for desired use.
Unstable
Instability. A general term to indicate various states of the atmosphere in which spontaneous convection will occur when prescribed criteria are met; indicative of turbulence.
Unusable Fuel
Fuel that cannot be consumed by the engine. This fuel is considered part of the empty weight of the aircraft.
Unusual attitude
An unintentional, unanticipated, or extreme aircraft attitude.
Unusual attitude
An unintentional, unanticipated, or extreme aircraft attitude.
Updraft
A localized upward current of air.
Upper front
A front aloft not extending to the earth’s surface.
Upslope fog
Fog formed when air flows upward over rising terrain and is, consequently, adiabatically cooled to or below its initial dew point.
Upwind Leg
A flight path parallel to the landing runway in the direction of landing.
URET
User Request Evaluation Tool
Urgency
A condition of being concerned about safety and of requiring timely but not immediate assistance; a potential distress condition.
Usability
The functionality of tests.
Usable Fuel
(GAMA) Fuel available for flight planning.
Useful Load
The weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation aircraft only.
Useful load
The weight of the pilot, copilot, passengers, baggage, usable fuel, and drainable oil. It is the basic empty weight subtracted from the maximum allowable gross weight. This term applies to general aviation aircraft only.
User Request Evaluation Tool (URET)
The URET helps provide enhanced, automated flight data management. URET is an automated tool provided at each radar position in selected en route facilities. It uses flight and radar data to determine present and future trajectories for all active and proposed aircraft flights. A graphic plan display depicts aircraft, traffic, and notification of predicted conflicts. Graphic routes for current plans and trial plans are displayed upon controller request. URET can generate a predicted conflict of two aircraft, or between aircraft and airspace.
User-defined Waypoint
User-defined waypoints typically are created by pilots for use in their own random RNAV direct navigation. They are newly established, unpublished airspace fixes that are designated geographic locations/positions that help provide positive course guidance for navigation and a means of checking progress on a flight. They may or may not be actually plotted by the pilot on enroute charts, but would normally be communicated to ATC in terms of bearing and distance or latitude/longitude. An example of user defined waypoints typically includes those derived from database-driven area navigation (RNAV) systems whereby latitude/longitude coordinate-based waypoints are generated by various means including keyboard input, and even electronic map mode functions used to establish waypoints with a cursor on the display. Another example is an offset phantom waypoint, which is a point in space formed by a bearing and distance from NAVAIDs such as VORs, VORTACs, and TACANs, using a variety of navigation systems.
User-defined waypoints
Waypoint location and other data which may be input by the user, this is the only GPS database information that may be altered (edited) by the user.
UTC
Coordinated Universal Time (abbreviated as UTC, and therefore often spelled out as Universal Time Coordinated and sometimes as Universal Coordinated Time) is the standard time common to every place in the world. Formerly and still widely called Greenwich Mean Time (GMT) and also World Time, UTC nominally reflects the mean solar time along the Earth´s prime meridian.
UTC
Coordinated Universal Time
Utility Category
An airplane that has a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of 12,500 pounds or less, and intended for limited acrobatic operation.
Utility Category
A category of aircraft certificated under 14 CFR part 23 and CAR part 3 that permits limited acrobatic maneuvers but restricts the weight and the CG range.
UWS
Urgent Weather SIGMET
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