U
- ultimate load
- ultra-light aircraft
- ultra high frequency
- ultralight aircraft
- ultralight vehicle
- UN number
- unaccompanied baggage
- unanticipated yaw
- unchecked baggage
- undercarriage
- undershoot
- underspeed condition
- undesired aircraft state
- unidentified baggage
- universal postal union
- universal precaution kit
- universal time
- universal time coordinated
- unknown state of acclimatisation
- unlawful interference
- unlawful seizure of aircraft
- unmanned aerial vehicle
- unmanned aircraft
- unmanned aircraft system
- unmanned free balloon
- unpaved runway edge marker
- unruly passengers
- unsealed cowling
- unstick speed
- up current
- updraft
- updraught
- upper-air observation
- upper-air sounding
- upset prevention and recovery
- upset training
- upwind
- US federal aviation administration
- usability factor
- useful load