UAE United Arab Emirates
UAV Unmanned (or uninhabited) aerial vehicle; contrast RPV.
UHCA Ultra-high capacity airliner.
UHF Ultra-high frequency.
UHT UnterstutuzungHubschrauber Tiger – the final anti-tank/fire support configuration of German Army Tigers, replacing original PAH-2.
UK United Kingdom.
ultralight Light aircraft with parameters below specified national limits, qualifying for less rigorous licensing; also known as microlight. See table.
1 Ultra leger motorise; criteria accepted by several European countries.
2 Plus 10 per cent for seaplanes and amphibians.
3 Plus 5 percent for seaplanes and amphibians.
UN United Nations.
upper surface blowing Turbofan jet expelled over upper surface of wing to increase lift.
usable fuel Total mass of fuel consumable in flight, usually 95 to 98 per cent of system capacity.
USAF United States Air Force.
USCG United States Coast Guard.
useful load Usable fuel and other consumables plus payload.
US gallon 0.83267 Imperial gallon; 3.785 litres.
USMC United States Marine Corps.
USN United States Navy.
USNR United States Naval Reserve.
USSR Union of Soviet Socialist Republics (see CIS).
UTTAS Utility Tactical Transport Aircraft System.