U
- U
- U/S
- UA
- UAC
- UAR
- UAS (1)
- UAS (2)
- UAT
- UAV
- UCAV
- UEET
- UFN
- UFTAA
- UHCA
- UHDT
- UHF
- UHF tactical air navigation aid
- UIC
- UIR
- ULA
- ULB
- ULCC
- ULD
- ulltra-high-capacity aircraft
- ULR
- ultra-high-capacity transport aircraft
- ultra-light aircraft
- ultra-low-cost carrier
- ultra efficient engine technology programme
- ultra high frequency
- ultra long range
- ultralight vehicle
- unable higher due traffic
- uncertainty phase
- uncrewed aircraft system
- undershoot/overshoot
- underwater locator beacon
- undesired aircraft state
- UNDP
- UNFCCC
- UNFCCC subsidiary body for scientific and technical advice
- UNICOM
- unidentified precipitation
- uniform
- unit load device
- united nations development programme
- united nations framework convention on climate changes
- universal federation of travel agents’ associations
- universal postal union
- universal precaution kit
- universal safety oversight audit programme
- universal time coordinated
- UNK
- unknown or undetermined
- unmanned aerial vehicle
- unmanned aircraft
- unmanned, or uninhabited, combat air vehicle
- unserviceable
- until further notice
- UP
- UPK
- upper air route
- upper area control centre
- upper flight information region
- upper information centre
- UPRT
- upset prevention and recovery
- UPU
- urban air mobility
- URET
- US federal aviation administration
- usability factor
- used serviceable material
- USM
- USM (2)
- USOAP
- USOS
- UTC
- utility-systems management