2/14/08 Pilot/Controller Glossary
PCG U-1
U
UDF-
(See DIRECTION FINDER.)
UHF-
(See ULTRAHIGH FREQUENCY.)
ULTRAHIGH FREQUENCY- The frequency band
between 300 and 3,000 MHz. The bank of radio
frequencies used for military air/ground voice
communications. In some instances this may go as
low as 225 MHz and still be referred to as UHF.
ULTRALIGHT VEHICLE- An aeronautical vehicle
operated for sport or recreational purposes which
does not require FAA registration, an airworthiness
certificate, nor pilot certification. They are primarily
single occupant vehicles, although some two‐place
vehicles are authorized for training purposes.
Operation of an ultralight vehicle in certain airspace
requires authorization from ATC.
(Refer to 14 CFR Part 103.)
UNABLE- Indicates inability to comply with a
specific instruction, request, or clearance.
UNASSOCIATED- A radar target that does not
display a data block with flight identification and
altitude information.
(See ASSOCIATED.)
UNDER THE HOOD- Indicates that the pilot is
using a hood to restrict visibility outside the cockpit
while simulating instrument flight. An appropriately
rated pilot is required in the other control seat while
this operation is being conducted.
(Refer to 14 CFR Part 91.)
UNFROZEN- The Scheduled Time of Arrival (STA)
tags, which are still being rescheduled by traffic
management advisor (TMA) calculations. The
aircraft will remain unfrozen until the time the
corresponding estimated time of arrival (ETA) tag
passes the preset freeze horizon for that aircraft's
stream class. At this point the automatic rescheduling
will stop, and the STA becomes “frozen.”
UNICOM- A nongovernment communication facility
which may provide airport information at certain
airports. Locations and frequencies of UNICOMs are
shown on aeronautical charts and publications.
(See AIRPORT/FACILITY DIRECTORY.)
(Refer to AIM.)
UNPUBLISHED ROUTE- A route for which no
minimum altitude is published or charted for pilot
use. It may include a direct route between NAVAIDs,
a radial, a radar vector, or a final approach course
beyond the segments of an instrument approach
procedure.
(See PUBLISHED ROUTE.)
(See ROUTE.)
UNRELIABLE (GPS/WAAS)- An advisory to
pilots indicating the expected level of service of the
GPS and/or WAAS may not be available. Pilots must
then determine the adequacy of the signal for desired
use.
UPWIND LEG-
(See TRAFFIC PATTERN.)
URET-
(See USER REQUEST EVALUATION TOOL.)
URGENCY- A condition of being concerned about
safety and of requiring timely but not immediate
assistance; a potential distress condition.
(See ICAO term URGENCY.)
URGENCY [ICAO]- A condition concerning the
safety of an aircraft or other vehicle, or of person on
board or in sight, but which does not require
immediate assistance.
USAFIB-
(See ARMY AVIATION FLIGHT INFORMATION
BULLETIN.)
USER REQUEST EVALUATION TOOL (URET)-
User Request Evaluation Tool is an automated tool
provided at each Radar Associate position in selected
En Route facilities. This tool utilizes flight and radar
data to determine present and future trajectories for
all active and proposal aircraft and provides
enhanced, automated flight data management.
UVDF-
(See DIRECTION FINDER.)

2/14/08 Pilot/Controller Glossary
PCG V-1
V
VASI-
(See VISUAL APPROACH SLOPE INDICATOR.)
VCOA-
(See VISUAL CLIMB OVER AIRPORT.)
VDF-
(See DIRECTION FINDER.)
VDP-
(See VISUAL DESCENT POINT.)
VECTOR- A heading issued to an aircraft to provide
navigational guidance by radar.
(See ICAO term RADAR VECTORING.)
VERIFY- Request confirmation of information;
e.g., “verify assigned altitude.”
VERIFY SPECIFIC DIRECTION OF TAKEOFF
(OR TURNS AFTER TAKEOFF)- Used by ATC to
ascertain an aircraft's direction of takeoff and/or
direction of turn after takeoff. It is normally used for
IFR departures from an airport not having a control
tower. When direct communication with the pilot is
not possible, the request and information may be
relayed through an FSS, dispatcher, or by other
means.
(See IFR TAKEOFF MINIMUMS AND
DEPARTURE PROCEDURES.)
VERTEX- The last fix adapted on the arrival speed
segments. Normally, it will be the outer marker of the
runway in use. However, it may be the actual
threshold or other suitable common point on the
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：航空信息手冊附錄(76)