Pilot/Controller Glossary

4/3/14

PCG U−1

U

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− A single-occupant

aeronautical vehicle operated for sport or recreational

purposes which does not require FAA registration, an

airworthiness certificate, nor pilot certification.

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 facil-

ity 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UNPUBLISHED ROUTE− A route for which no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.