Glossary

This glossary contains information on terms, phrases and abbreviations used by the Aviation industry. While this list does not include all aviation terminology, it is the purpose of this glossary to aid the general viewer in better understanding aviation terms as it pertains to content on this website. A full list of aviation terminology can be found here.
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U

UHF.

See ultra-high 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.

Ultra-high frequency (UHF).

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

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.

Underpower.

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

Unusual attitude.

An unintentional, unanticipated, or extreme aircraft attitude.

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-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.