W  U  V  V/PD —Vehicle/pedestrian deviation  VALE —voluntary airport low emission  VASI —visual approach slope indicator  VDME —VOR with distance measuring equipment  VDP —visual descent point  VF —voice frequency  VFR —visual flight rules  VGSI —visual glide slope indicator  VHF —very high frequency  VIA —by way of  VICE —instead/versus  VIS —visibility  VLF —very low frequency  VMC —visual meteorological conditions  VNAV —visual navigational aids  VNTSC —Volpe National Transportation System Center  VOL —volume  VON —virtual on-net  VOR —VHF omnidirectional range  VOR/DME —VHF omnidirectional range/distance  measuring equipment  VORTAC —VOR and TACAN (collocated)  VOT —VOR Test Facility  VP/D —vehicle/pedestrian deviation  VRS —voice recording system  VSCS —voice switching and control system  VTA —vertex time of arrival  VTAC —VOR and TACAN (collocated)  VTOL —vertical takeoff and landing  VTS —voice telecommunications system  W —west  WAAS —Wide Area Augmentation System  WAN —wide area network  WB —westbound  WC —work center  WCP —Weather Communications Processor  WECO —Western Electric Company  WED —Wednesday  WEF —with effect from; effective from  WESCOM —Western Electric Satellite Communications  WI —within  WIE —with immediate effect, or effective immediately  WKDAYS —Monday through Friday  WKEND —Saturday and Sunday  WMSC —Weather Message Switching Center  WMSCR —Weather Message Switching Center Replacement  WND —wind  WPT —waypoint  WSCMO —Weather Service Contract Meteorological  Observatory  WSFO —Weather Service Forecast Office  WSMO —Weather Service Meteorological Observatory  WSO —Weather Service Office  WSR —wet snow on runway(s)  WTHR —weather  WTR —water on runway(s)  WX —weather  UAS —unmanned aircraft systems  UFN —until further notice  UHF —ultra high frequency  UNAVBL —unavailable  UNLGTD —unlighted  UNMKD —unmarked  UNMNT —unmonitored  UNREL —unreliable  UNUSBL —unusable  URA —Uniform Relocation Assistance and Real Property  Acquisition Policies Act of 1970  USAF —United States Air Force  USC —United States Code  USOC —Uniform Service Order Code  B-12 