- UAV Unmanned (or uninhabited) aerial vehicle; contrast RPV.
- UHCA Ultra-high capacity airliner.
- UHF Ultra-high frequency.
- ultralight Light aircraft with parameters below specified national limits, qualifying for less rigorous licensing; also known as microlight. See table.
- 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.
- useful load Usable fuel and other consumables plus payload.
- US gallon 0.83267 Imperial gallon; 3.785 litres.
- UV Ultra-violet.
