A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

UUpward (tendency in RVR during previous 10 minutes)
UUpper air analysis (current chart)
UABUntil advised by ...
UACUpper area control centre
UARUpper air route
UDFUltra high frequency direction−finding station
UFNUntil further notice
UHDTUnable higher due traffic
UHFUltra high frequency (300 to 3 000 MHz)
UICUpper information centre
UIRUpper flight information region
ULRUltra long range
UNAUnable
UNAPUnable to approve
UNLUnlimited
UNRELUnreliable
U/SUnserviceable
UTAUpper control area
UTCCo−ordinated Universal Time
UUPUpdate use plan
UPSUninterruptible power supply
(C) 2012-18 Jan Hrkal