U | Upward (tendency in RVR during previous 10 minutes) |
U | Upper air analysis (current chart) |
UAB | Until advised by ... |
UAC | Upper area control centre |
UAR | Upper air route |
UDF | Ultra high frequency direction−finding station |
UFN | Until further notice |
UHDT | Unable higher due traffic |
UHF | Ultra high frequency (300 to 3 000 MHz) |
UIC | Upper information centre |
UIR | Upper flight information region |
ULR | Ultra long range |
UNA | Unable |
UNAP | Unable to approve |
UNL | Unlimited |
UNREL | Unreliable |
U/S | Unserviceable |
UTA | Upper control area |
UTC | Co−ordinated Universal Time |
UUP | Update use plan |
UPS | Uninterruptible power supply |