Aeronautical Terms beginning with U

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 They are newly established, unpublished airspace fixes that are designated geographic locations/positions that help provide positive course guidance for navigation and a means of checking progress on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 userdefined 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.

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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.

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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.

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Unfeathering Accumulator

Tanks that hold oil under pressure which can be used to unfeather a propeller.

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UNICOM

A non-government air/ground radio communication station which may provide airport information at public use airports where there is no tower or FSS.

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Unusable Fuel

Fuel that cannot be consumed by the engine. This fuel is considered part of the empty weight of the aircraft.

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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.

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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.

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UHF

See ultra-high frequency.

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Ultra-high frequency (UHF)

The range of electromagnetic frequencies between 962 MHz and 1213 MHz.

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Uncaging

Unlocking the gimbals of a gyroscopic instrument, making it susceptible to damage by abrupt flight maneuvers or rough handling.

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Underpower

Using less power than required for the purpose of achieving a faster rate of airspeed change.

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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.

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Unusual attitude

An unintentional, unanticipated, or extreme aircraft attitude.

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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.

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Understanding

A basic level of learning at which a student comprehends or grasps the nature or meaning of something.

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Usability

The functionality of tests.

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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.

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Uncontrolled Airport

An airport that does not have an operating control tower. Two-way radio communications are not required at uncontrolled airports, although it is good operating practice for pilots to transmit their intentions on the specified frequency.

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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.

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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.

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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.

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